SPEC Real Sound RSA-M3EX Reference 120w Integrated amp w remote

SC 05 AI RSA M3
NZ$ 12,995.00 ea (incl. GST)
SPEC Corp

Our “Real-Sound” brings the true richness of music - Real-Sound” BRINGS THE BREATHS OF PERFORMER JUST IN FRONT OF YOU

New

REAL SOUND AMPLIFIERS RSA-M3EX - Real, new-generation class-D amplifiers with latest highly accurate PWM switching devices

A lot of people may tend to think Class-D means "digital", however, SPEC amplifiers, re "Class-D analogue amplifier" has a very similar circuit as tube amps, only the output tube was replaced by special PWM switching devise, they offer a dynamic engaging musical presentation in a lovely compact form.

The SPEC RSA-M3 EX Real Sound Amplifier is a stereo integrated amplifier with three RCA inputs and one XLR input. With a flip of switch the SPEC RSA-M3 EX can also be used as a dedicated amplifier with a preamplifier.

By employing the latest developed class-D amplifier devices, power MOS-FET achieves ideal highly accurate current switching in the power stage, and high-voltage gate driver IC with excellent time-axis control maximises the ultimate PWM switching. The exceptional performance of the class-D devices ensures ultimate real-sound with quality damping in the mid to low ranges even when driving low-efficiency speakers. Furthermore, the sweet and rich tonal character in the mid to high ranges of the amplifier is almost like the tone of the best triode tube amplifiers.

Superb power source of RSA-F33EX / RSA-M3EX / RSA-V1EX ensures the real musical sound

In order to maximise the potential of the unprecedented high performance of this amplifier (power utilisation in the power stage at maximum output; 96%), we daringly employed a classical and very simple plus/minus power source composed of minimal numbers of high quality components, such as only transformers, bridge-diodes and capacitors.

Specially selected parts of low-pass filter contribute to the Real-Sound

The sound of this class-D amplifier owes a lot to the individual parts of low-pass filter in the final stage of the amplifier. The capacitor and the coil employed for the low-pass filter were custom-ordered after careful listening tests and guarantee the excellent musical sound of RSA-M3EX.

Wooden base-chassis and insulators to realise rich and beautiful instrument-like sound. In an unusual endeavour for an audio amplifier, natural wood was used for the base chassis and insulators.

REVIEW SUMMARY from The Ear:
After an enthusiastic review the conclusion can only be positive for the SPEC RSA-M3EX amplifier. I had to get used to the amp, it first seemed a little plain and underpowered compared to my own amplifiers. An opinion that soon needed adjustment and turned 180 degrees into appreciation of its pure, delicate and undistorted sound quality. Deep bass notes might seem to lack power at first, but soon I found out that bass is so tight, fast and uncoloured that it only attracts less attention. This was even clearer after changing from small monitor speakers to large transmission lines. Also consider the near perfect stereo image of the RSA-M3EX, the spatial sound and the purity of the reproduced music. Every class D amplifier I have heard had a specific class D signature that I could never get used to, I always returned to more conventional designs with a preference for class A. That is until I listened to the SPEC RSA-M3EX, an amplifier that makes me forget the technology and sounds so good that I would like to own one... A final word: I often get the impression that Japanese high end products have a soul, a part of the designers aura stays under the hood. The SPEC is among these products, Shirokazu Yazaki has me under his spell.

REVIEW SUMMARY from Positive Feedback:
From the first moment that I saw, touched, and powered my hi-fi systems with Yazaki-san's SPEC RSA-M3 EX Real Sound Amplifier I was deeply impressed with what he has accomplished. There is a certain irresistible 'sensuality' sonically, musically, and even visually to the SPEC RSA-M3 EX Real Sound Amplifier that makes it quite captivating amplifier to listen to music with.
The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce.
We talked about the SPEC and how its highs were spot-on perfect and natural sounding too, and Julie's vocals were stunningly natural, with absolutely no unnatural sibilance. The bass response was extended and full of nuance, and even though it was only 60 watts, the SPEC could really deliver the dynamic swings when called upon. The SPEC was deceptively powerful, and when loafing along it sounds only about as powerful as my 25 watt MC225, but when you really crank it up it never misses a beat and sounds astonishingly good, even at very loud 'blow out the windows' levels. In short, when we sitting there listening to the SPEC play music we came to the conclusion that it was one of the most perfectly voiced amplifiers we'd ever heard.
Everyone who has heard the SPEC Real Sound Amplifier, including Cindy, has made the comment of how rich and natural the SPEC sounds (in a timbral and tone colour sense), and Cindy added how it drew out many subtleties in the music, and had an ability "to remind you that recordings from your past are 'old friends'". I thought that the last was a particularly interesting comment, because the SPEC does indeed have an exceptional ability to portray music's emotional impact. It reminds you of how you felt when you heard the music for the first time, and it brings back all those feelings in a flood as you listen to the music. The SPEC's is a very beautiful presentation of tone colour.
If you're interested in an amplifier with the beauty, tone colour, timbral naturalness, and rich stereoscopic musicality of the best vacuum tube designs in a non-fussy and classy solid-state design, I suggest that you listen to the SPEC RSA-M3 EX amplifier. You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.

Here's an interesting observation: The new-generation class-D amplification modules developed by Mr. Honda-san for International Rectifier specifically for high-performance audio use were informed by that same sort of listening insight into tone color and timbral textures that he and Mr. Yazaki-san enjoyed while listening to jazz on Yazaki-san's DA30 DH-SET stereo amplifier and his Altec & Onken horn loudspeaker system.

Mr. Yazaki-san says, "By employing Mr. Honda-san's latest developed class-D amplifier devices, the power MOS-FETs achieve highly accurate current switching in the power stage, and a high-voltage gate driver IC with excellent time-axis control maximizes the ultimate PWM switching. The exceptional performance of these class-D devices ensures ultimate real sound with quality damping in the mid to low ranges even when driving low-efficiency speakers. Furthermore, the sweet and rich tonal character in the mid to high ranges of the amplifier is almost like the tone of the very best triode tube amplifiers."

The audio board in the SPEC RSA-M3 EX is located at the final stage of the amplifier just before speaker terminals, and consists of a low-pass filter and a snubber circuit (an energy-absorbing circuit used to suppress the voltage spikes when a switch opens). Mr. Yazaki-san told me, "This filter and the circuit are very important for the sound quality. In other words, M3EX's tonal quality depends largely on the parts used in these circuits."

"You can see two hermetic oil-filled capacitors on the audio board made for us by Arizona Capacitors, Inc. Yes, these capacitors are custom-made for us and each capacitor has a different tonal character. One has a beautiful mid-to-high end, and the other has a rich mid-to-low range like a vintage capacitor."

"And another special quality part are the two little black cubic boxes you can see on the audio board, which are custom Mica capacitors that are custom made for us in Japan, and they are one of the best sounding capacitors of all ages for a signal capacitor. These days Mica capacitors are so rare to have, but they are wonderful sounding, highly transparent like a blue sky. The clarity of the Mica capacitors combined with the rich sound of the oil-filled capacitors gives the really incredible deep tonal character to the SPEC RSA-M3 EX."

"The ideal sounding capacitor does not exist so we blend these different types of capacitors to get our favourite sound. The same is true for our power supply.

"In our DC power supply we use the latest Silicon Carbide (SiC) Schottky diodes, which provide a powerful and noise-free sound. We select the diodes by ear for the best sound, and we choose only best ones, often only one out of ten that we listen to. The efficiency of class-D amplifier is far higher than any other semiconductor amplifier, and it runs up to 96% efficiency at full power. A traditional class-A or class-AB amplifier's final stage efficiency is only 20 to 30%. So these types of amplifier need big heat sinks. Our class-D amplifier is very sensitive to the quality of the power supply. Yes, we could say, the quality of the power supply determines directly the final sound quality. So we blended three types of capacitors, and this parallel connection of the capacitors reduces ESR (equivalent series resistance) in the entire range, which leads to a clear and also powerful sound. The oil-filled capacitors could compensate the mid to high range characteristic of electrolytic capacitors and bring out high speed, rich tonal character."

"Our power switch is a type of switch used only for professional-use, for example in aircraft. It has high capacity and is very rugged."

I would also add that it is a very interesting power switch to use, and it has a very deluxe feel to it. It sure is a lot nicer than any of the switches in the old Cessna 150 aircraft I owned as a kid! To turn on the amplifier you first pull the spring-loaded locking switch out, and then switch it into position, and it locks in place. I've never encountered one like it before.

"The selector switch is made in Japan for use in instruments for the communications industry." 

"The wires are Belden 1503A, which we found in our evaluations to be one of the very best cables for inner signal use. The switch is hand-assembled by a technician, and is a higher-quality successor to the style of switch assembly used in the Marantz model #7 for input selection."

"The SPEC variable resistor is not your usual variable resistor, and no signal current flows in this variable resistor. It only works as a position-sensitive detector, and there is a very precise electronic volume device in our class-D amplifier unit that decides the gain of amplifier according to the information from this detector. We regard this variable resistor as very important for the tactile feeling of adjusting the volume, so we custom order it with a special curve and torque for just the right feel. The resistor is sealed for long-term reliability."

"The input selector and volume knobs are made for us in Japan."

The base of the RSA-M3 EX 's chassis is made of a solid laminated panel of European spruce from Austria. Mr. Yazaki-san says, "Spruce has long been used for the top plate of stringed instruments and the soundboard of pianos, and is known as a material with excellent sound quality that provides quick vibration transmission and moderate damping."

I thought that the spruce base for the RSA-M3 EX's chassis was intriguing, and I don't recall seeing anyone doing that before. My Gibson Advanced Jumbo guitar has an Adirondack spruce top and Brazilian rosewood back and sides (above), and it sure sounds fine. Also, in the photos of my listening / living room in my various articles at Positive Feedback Online you'll notice that all my audio equipment is on natural wood supports, like my solid walnut rack for my vintage McIntosh gear and turntable, including my Duelund external crossovers, and all the Sablon Audio Panatela speaker cables. Wood just makes audio gear sound better.

Mr. Yazaki-san, went on to say, "The combination of this material with the rigid steel chassis produces a rich and pleasant sound. The footers on the bottom of the wood base are a combination of pure painted maple from Hokkaido, Japan, and hickory from North America. Maple has excellent strength and is used in combination with spruce for the sides and backs of stringed instruments. Hickory is a hard material that absorbs impact well and is used for drumsticks, for example. The maple and hickory moderates the resonance of the spruce to help provide a rich musicality."

From the development of the class-D amplifier modules, to the selection of every single component that makes up the SPEC RSA-M3 EX Real Sound Amplifier, Mr. Yazaki-san and the entire SPEC team paid serious attention to voicing the amplifier to sound as musically satisfying as the transparent, beautiful tone colour, rich, and dynamic nature of the DA30 DH-SET reference amplifier.

Specifications

Reviews

Testimonials

Specifications

Maximum output - 2x 120w ×@ 4ohm, 2x 90w @ 6ohm, 2x 60w @ 8ohm
Frequency response - 10 Hz - 30 kHz ±1dB (6ohm, 1W)
Harmonic distortion ratio - 0.02% (at 1 kHz, 80% output)
Input sensitivity, gain - 300 mVrms, 37.3 dB (at MAX volume, 6ohm, 1kHz, unbalanced input)
Line input terminals - XLR input: 1 RCA inputs: 3
Speaker terminal - 1pr
Power voltage - 230vac 50Hz
Electrical consumption - With no signal: 15 W, during maximum output: 215 W (8 ohm, 100 Hz)
External dimensions - 440 mm (width) × 125 mm (height) × 414 mm (depth)
Weight - 15.5kg
Remote - optional extra RSR-L Remote Control

Reviews

If you want what it does—mimic valve sound to this extent whilst throwing in modern power efficiency which SET-ish class A transistor amps certainly don't—then this could be the top game in town and play smack in the heart of your most desirable district.
Sarjan Ebaen


REVIEW SUMMARY: Were I a Spendor or Harbeth fan looking to maximise the known virtues of those warm Brit boxes, the RSA-M3EX could be it.

It really is about a powerful dose of classic valve sound. The big difference is cool running power; current-critical load happiness into low impedances; operational silence; and stable performance without the insidiously slow ageing of power triodes and its deleterious sonic effect.

With Boenicke Audio B10. speakers it was as fine a pairing as the eggs had been, extending lower without being plagued by ports for superior sealed bass, the ambient-rich sound favoured by Sven Boenicke—hence his penchant for lateral drivers—responded favourably to the amp's tonal weight. I really suspect Yazaki-San himself would have approved.

If Yazaki-San's results surprise us, it's only because none before have endeavoured to bend switching transistors quite so far in this direction. Henceforth SPEC marks that spot.

EXTENDED REVIEW: When a designer traces his audiophile lineage back some 38 years—to when Jean Hiraga first imported NOS tubes to Japan to promptly build himself a DA30-based SET with WE310A driver/274B rectifier followed by a vintage horn speaker system based on Altec 414A woofers, Onken OS-500MT mid/high drivers and matching SC-500 wooden horns—you just know his sonic north. When such a designer worked at Teac on their open-reel recorders as mechanical engineer and subsequently for nearly two decades at Pioneer where he was involved with more tape decks—the Nakamichi dragon-slaying CT-95 was a highlight—and the world's first true universal player whilst continuously evolving/upgrading his original SET... then you also know that despite newfangled technologies a love of vintage tube sound remained alive throughout.

When Shirokazu Yazaki joined forces with International Rectifier engineer Tsutomu Banno to launch SPEC Corp. on February 6th 2010, he had a most contrarious notion. He meant to advance his beloved valve sound with the very latest in ultra-efficient super high-speed switching power Mosfets which Banno had helped develop during his IR tenure. Yazaki-San is adamant that class D circuits are particularly vulnerable to the quality of their power supply and low-pass filter. With him the former becomes a massively overbuilt linear affair, the latter an ultra-simple inductor/cap circuit albeit based on rare custom parts. "By the end of 2009 I had reached the conclusion that the best capacitor to use in such a filter was the vintage oil-filled type marked 'hermetic seal' from West Cap, part N° CPV09 0.47/600 made for the US military in 1967. It turned out that the original capacitor manufacturer had survived in Tucson, Arizona. In the early 90s they'd changed their name to Arizona Capacitors Inc and from West Cap taken over huge production facilities and endless engineering drawings. As their Japanese distributor since the summer of 2011 we've worked closely with Arizona Capacitors to sell their quality custom oil-filled capacitors in our domestic market. We were thus able to adopt their fantastic capacitors for all our amplifiers. If I were to isolate something very important about the true potential of D-class amplifiers, it's how they control the inevitable back electromotive force from the speakers. In D-class amplifier the current of the back EMF is directed back at the power supply, not the feedback loop of traditional transistor amps where it undermines their phase integrity with dynamic music signal."

"The ultimate performance of a class D amp also depends on just how accurately it implements its pulse-width modulation switching. Here International Rectifier's DirectFet output device with a high-voltage invariant IC driver of excellent time axis performance really establishes new parameters. Other well-known class D advances are almost triple the efficiency of conventional semiconductor amps; instant current delivery; bidirectional energy transfer to regenerate back-electromotive forces in the power supply; and excellent linearity."

In the SPEC book this makes class D a 3rd-generation proposition preceded by the 1st generation of tube amps which were natural and rich of tone but of limited bandwidth and incapable of driving modern low-efficiency speakers; and the 2ndgeneration of traditional transistor amps which had high power, certain disadvantages based on their implementation of negative feedback plus wasteful energy consumption. Done right they believe that class D can combine the very organic presentation of tube amps with the raw drive power of transistor amps to become a best-of-both-worlds hybrid.

The use of specific tone woods for SPEC's metal enclosure plinth reminds us. Yazaki-San's audio background began in mechanical engineering. Just like his deliberate exploitation of NOS-type capacitor sonics*, this indicates strategic voicing or circuit tuning.

As such SPEC's approach to class D differs from Hypex/Ncore's Bruno Putzeys whose own blog contains comments like "...the fly in the ointment came as I slid our preamp proto (later baptized Makua) into a rack for one such demo. To understand my befuddlement you ought to know that said rack space had just been vacated by what I’d call a glorified variac but what was probably an 'autoformer-based passive preamplifier'. It had two big knobs, one for source (three positions) and one for gain (twenty-four 2dB steps). Rotating them took considerable force and both went alarmingly clunk as one did so. It was in other words esoteric. And its distributor had just asked me whether Makua had a remote control. Here’s the mistake I made not including one. When a product looks like it’s been designed in a basement decked out with Buddhist paraphernalia and the electrical circuitry—such as it may contain—is a highly intimate statement of one’s most personal artistic genius, nobody asks for a remote control. One doesn’t question High Art and demand that it be practical. But as soon as some degree of engineering is evident like the presence of an actual gain stage or the absence of distortion, the product becomes pedestrian and it’ll have to use the zebra crossing like anyone else."

The RSA-M3EX integrated combines the esoteric—tuned wood footers, tonewood plinth, vintage-style oil-filled caps—then crosses the zebra stripes with an optional costly remote executed differently once again as a wired wooden receiver box. That separation keeps this circuit and its potentially noisy display completely isolated from the main box. It also means that someone not into remote volume needn't pay for it.

Seeing how SPEC have four different integrated amplifier models—the RSA-717EX, F3EX, M3EX and V1EX—but little to distinguish them to the naked eye (the 717EX is smallest as the next photo shows on the top left-most rack), I asked Yoshi Hontani, English-speaking Japanese audio exporter for SPEC and other Japanese brands like Leben Hifi, to talk me through their specifics on behalf of Shirokazu Yazaki.

"We think of the M3EX as our main export model. It’s very important for us and thus much improved over the domestic M1 version. To clarify the differences between RSA-F3EX and M3EX, I should first point at their commonalities. The class-D amplifier module with IR output devices and R-core power transformer are exactly the same. Hence the power and sonic structure are the same too. But certain parts in the power supply, low pass filter and snubber circuit differ. And it is these differences which determine the particular sonic character of the F3EX and M3EX. In the M3EX power supply we changed the rectifier diode from an ultra-fast soft recovery type to the very latest SiC (silicon carbide) Schottky. 

"This SiC diode was first introduced last fall by ROHM, a semiconductor maker in Japan. We made our selection only after hearing 10 different types of SiC diodes during a ROHM presentation. As a result the winning unit has very powerful high-speed bass and a completely noise-free treble. Simultaneously we also evaluated high-capacity industrial soft-recovery versions used in the F1 and F3EX which are very detailed nuanced and rich.

"I felt that the sound of this diode performed much like a high-quality tube rectifier. At present I thus couldn't decide which was the better diode - the one in the M3EX or F3EX. The amps' actual sound character is directly related to this choice of diode. Both also adopt the Arizona Capacitors Inc hermetic-seal oil-filled caps and custom mica caps in their low-pass and snubber circuits. Because we developed a very close working relationship with this company for the last three years, we have access to two types of custom oil-filled caps. Our REQ-STEX phono preamplifier uses both of them. For our power amps we use the C85805 for the F3EX and the C30509 and C85805 for the M3EX. The F3EX connects two half-size caps in parallel in both the low-pass and snubber circuits to pare down equivalent series resistance. The M3EX uses the C50309 in the low-pass filter and the C85805 in the snubber circuit. Thus the sonic differences between these amps also relate a bit to this choice of capacitor. I myself have many experiences with many kinds of mil-spec vintage oil-filled caps. This eventually led to us Arizona Cap. not only for the low-pass filters, snubber circuits and power supplies of our class D amps but also for our speaker-impedance compensator boxes RSP-301 and 501EX. And I use Arizona caps in my old valve amplifiers coupling their driver and output tubes and in their power supplies.

"So I listen to music with Arizona caps every day at the office and in my home. I thus have some very specific opinions about their sound. The C85805 is a KP/AL/mineral-oil part, the C30509 a KP/MY/AL/mineral-oil type. Our chief engineer Mr. Banno and I appreciate and love them both. The C85805 has an extremely beautiful saturated midrange and treble to be perfectly matched to female vocals and stringed instruments like the violin. The sound is very graceful and pure. This comes from genuine-pulp Kraft paper dielectric. It's a material very close to nature and sounds sweet. The dielectric for the C30509 adds Mylar film. Its sound is almost perfectly balanced top to bottom but the most spectacular registers are the lower ones. Compared to the old vintage West Cap style this sound has better bass speed and a smoother treble to better fit today's broader bandwidth high-resolution music. Yet it retains the desirable warm vintage color of famous US caps like the Sprague 'Bumble Bee', 'Black Cat' and 'Vitamin Q'. I became convinced that the C30509 is the true successor to the famous West Cap vintage capacitors made in the US. I thus decided to distribute these caps in Japan for our domestic valve-amp fans in the summer of 2011. It took time but the nameArizona Capacitors has gradually become very familiar to Japanese DIYers. The common virtue of both types of Arizona caps is their extraordinarily natural sweet sound which gets even more so over prolonged use. Above all it's evidence of the real thing from my personal view on hifi parts.

"I should return to the sonic character we aimed for with the RSA-F3EX and M3EX which reflects the C85805 and C30509 capacitors. There also are the mica caps whose sound our catalog describes 'as transparent as a blue sky'. I feel that mica caps have the best reliability and HF performance. So it becomes the combination of our custom oil-filled and mica caps which exceeds the performance of any other type of signal-path cap I'm aware of. In the end it's this very strategic very well-researched combination of parts which defines our amplifier sound and especially the F3EX and M3EX models. Mechanically our RSA-F3EX as the top model also gets heavier aluminium panels which directly reflects in its higher price. Here we also added very special electrolytics to the power supply. Like magic this vastly improved ambient retrieval over the F1. The M3EX meanwhile benefits from the SiC rectifier to enrich its already powerful sound across the entire range. If one proposed two sides of the true meaning of enjoying the music, one would be delight, the other healing. In this sense the RSA-M3EX would be delight whilst the RSA-F3EX's tone would have some healing effects." 

So we have it in writing. Even its own designer doesn't consider the RSA-M3EX to be just neutral. For that he offers the more affordable V1EX.

What's wrong with just neutral? Wrong question. The V1EX covers that base. It'd be better to ask why Yazaki-San might hold a different personal preference; and why he believes others might join him in that costlier choice. For probable cause we refer back to an interview we published in a previous review of SPEC's phono stage. "Around the end of the 1990s and by the beginning of the millennium, Pioneer had reached its zenith. Our engineering team enjoyed the rare opportunity to develop as high-end a DVD player as the AX10. We also had a well-designed spacious listening room. We could select high-priced speakers, preamps and power amplifiers to be our reference for the development of the AX10. I remember that I bought a pair of B&W 801 which then was the reference of specialist audio shops in Japan. Of course B&W 801 were always driven by high-power semiconductor amplifiers of various famous domestic and foreign brands. Yet Mr. Banno and I were never moved by the sound of this high-end audio system. The sound was like watching miniature paintings. We could hear all the details but were never touched by the music. We felt that the sound was very precise but one-dimensional. It lacked any real dynamics and rhythm. When I returned home and listened to music over my old high-efficiency system, I was once again intoxicated by the playback which was so transparent, natural and organic. I felt that the difference came from the distinction of certain dynamic characteristics between these two systems, not merely specific static qualities."

In a later manifesto, Shirokazu put it this way: "With the mainstream of recent efforts pursuing audio quality based on the combination of low-efficiency speakers and high-power transistor amplifiers, what's really possible is merely a sound that expands on or behind the plane of the speakers by emphasising a feeling of elaborateness, wide frequency response and a rather thin tonal quality. Even if such a sound presents a high degree of perfection from the point of view of audio measurements, does it really bring us the joy and excitement of music?"

Shirokazu is far from alone questioning whether modern hifi hasn't made a bad turn somewhere to keep heading in the wrong direction. Zu's Sean Casey has long been on record on the same matter. So have various others. They all believe that in the pursuit of extreme resolution and parallel demands for ever smaller speakers of increased loudness and bass capabilities, something vital was lost. This view doesn't sugarcoat the fact that Western Electric-day systems had limited bandwidth and high distortion. It's not about returning to 50Hz-15kHz-3dB bandwidth and with it a wholesale elimination of modern music anchored in low bass. It's about maintaining legitimate gains made since whilst recovering aspects of valve tone and the easeful dynamics of vintage high-efficiency hornspeakers they feel have been sacrificed or diluted.

Means. Motive. Opportunity.

SPEC's solution bypasses the SET/horn revival which in Japan remains very active. They pursue conventional dynamic speakers of ±88dB efficiency to make a similar type of sound. For said purposes they harness the very latest in analog switching technology. That's admittedly somewhat radical. It's also quite in contrast again to our earlier mentioned Bruno Putzeys who applies very advanced math and error correction to obtain measurable neutrality and ultra-low distortion. SPEC actually treat their class D amps as valve circuits. They merely swap output devices. Tubes out, DirectFets in. That grossly oversimplifies things but points straight at the heart of the matter. A minor rebellion like Xalapas' El Candigato? Given the strategic component allocations hinted at above, should we assume that what primarily distinguishes the various SPEC amplifiers is different voicing? Shirokazu after all knows exactly how each part of their circuit contributes to the final sound and what to specifically change if one meant to shift sonics in a particular direction.

"The first SPEC model was the RSA-F1. It implemented our full technology with the highest-grade parts and components without regard to production cost. Based on this model we further improved the export version RSA-F3EX mainly by upgrading core power supply components. This made the sound even more graceful and sophisticated. Our second model became the RSA-V1 where intent was to reduce build cost with more affordable parts. The export version V1EX upgraded some of those again. The RSA-M1 was tuned specifically for JBL and Jazz lovers to increase dynamics in the mid to low registers and make the sound more active. The M1EX export version was further improved to cope with all manner of musical categories whilst maintaining the original sound signature.The RSA-717EX is a recent development to undercut the price of even the V1EX by applying a switch-mode power supply. This achieves similar sound to the RSA-V1EX and perhaps is superior for certain music. 

"Although the difference between F3EX and V1EX isn't double, the F3EX is the ultimate expression of our technology as implemented with the very best parts possible. Given this, if I had sufficient money to buy an F3EX, I might chose the F3EX over the M3EX to get the best even if I couldn't distinguish a clear sonic difference. If I couldn't afford the F3EX, I might convince myself that the M3EX was better for my favored music or that the difference was insufficient to pay double. We consider the V1EX our entry-level model. People who don't care about its SMPS will instead go for the 717EX whose sound exceeded our own expectations for it. In conclusion there are clear sonic differences between our three models (the 717EX is an exception). One final advantage of our amps are their superior linear power supplies. They convert over 95% of the wall power into actual output power. Usual transistor amps manage only about a 25% conversion margin. From this follows that our amps drive speakers three times as power hungry as our raw specs would suggest."

The published power ratings for the RSA-717EX/V1EX are 50/100wpc into 8/4Ω and 60/120wpc for the RSA-M3EX/F3EX. Following SPEC's math one should consider them actual 150/300wpc and 180/360wpc ratings versus conventional class A and A/B amps. Surprising perhaps in the maker's descriptions about their lineup is specific voicing, sometimes even for specific speaker brands or music styles; better export than domestic versions; and implied superiority of linear over switching power supplies even though the model with the SMPS is called "perhaps better for certain music" over its equivalent with the linear supply. Either these lines are blurrier and more ambiguous than good/better/best ideologies would wish; or like any loving parent Yazaki-San felt hard-pressed to be too specific about classifying his offspring. On price tiers SPEC hadn't officially begun exporting all models but tentative projections anticipate €18.000/$24.000 for the RSA-F3EX i.e. twice our review model; and €7.2000|$9.500 for the RSA-V1EX.

The remote option is most unusual. It obviously doesn't add a motor to the master knob. Thus having the latter fully counter clockwise can't produce any sound no matter how vigorously one presses the up button on the wand or in dying hope observes the LED confirmation of the display which shows received commands. That's because the remote only operates "within a ±10dB window against the level set by the main volume, i.e. in 4 steps up and 7 down. There's an additional 20-30dB of attenuation or full muting with the wand's attenuate button." The plastic casing with its IR circuitry sits inside the wooden box buffered by simple foam squares all around. This leaves some play. Shaking the wooden case thus elicits a bit of inner movement. To be blunt, €900/$1.200 for this strange and functionally crippled contraption with tiny 9V switch-mode power supply is excessive. It also looks odd and adds two cables to the usual spaghetti salad behind the gear. It does however allow the amp to be installed out of sight whilst retaining a modicum of volume control.

For the obligatory inside tour one has to move beyond the four strategic box shields. If one does here's what the bird's eye view on the main board would show which is usually concealed beneath the biggest internal case. 

Here we go straight to the 2-channel International Rectifier amplifier module. It piggybacks on SPEC's main board right in front of the low-pass filter air-core inductors and caps. The short flying leads from the main board to the output terminals leave via massive screw-down blocks. This termination method is far sturdier than the ubiquitous solder joints to a PCB. Its presence here indicates very high current flow at that precise juncture

The dual-mono IR module runs two clocks per channel. The main board contains a three-pole external clock switch (likely an assembly feature to fix the precision trim pot setting) and a socketed International Rectifier version of the Japanese Tachyonix Corp. 3310 volume controller chip. The heat-sinked module accommodates three 78M12CT voltage regulators.

As this inspection confirmed, the RSA-M3EX is very far from just another ICEpower, Hypex, PowerSoft, Abletec, AnaLight or Pascal affair. Just so that plain fact wouldn't safeguard it from being compared directly to such 'off-the-shelf' D-class competitors.

For modified Hypex UcD400 with linear power supply and Lundahl input transformer I had the $5.000/pr Aualic Merek monos on loan. For Pascal I had the modified S-PRO-based €3.250 Gato Audio DIA-250 with IR DirectFET output transistors like the SPEC. Both are from rather to very much more cost-effective. Both also offer considerably higher power. The Danish integrated even adds features like a 24/192 DAC with asynchronous XMOS-based USB, a beautifully legible dot-matrix white display and remote control over the amp's complete volume range.

Well prior to any listening yet, the gavel thus apeared to come down hard on the RSA-M3EX's price and its very peculiar also very costly add-on remote control. Nothing like a bit of competition to keep things honest. With that out of the way, how about sonics? For that assessment I'd use two very different speakers - the soundkaos Wave 40 and the AudioSolutions Rhapsody 200.

The first is a 92.5dB Raal ribbon-augmented German 8-inch widebander in a complex Swiss tone wood enclosure with very short line/scoop loading and low-order filters. This is the type of speaker conventionally mated to low-power SET amps (or in my own case Nelson Pass' SIT-1 transistor equivalent). The second is a typical 'muscle-amp' speaker by virtue of a challenging impedance curve and seriously underdamped dual-port bass alignment. It thrives on high damping factor i.e. low output impedance. As a 5-driver 3-way with higher-order networks, the dual-woofer floorstanders also responds well to power. To keep things honest against traditional amp topologies I'd use the aforementioned FirstWatt SIT-1 monos; Crayon Audio's CFA-1.2 which despite its medium power output handles the Rhapsody 200 beautifully and sonically can be thought of as a functionally and power-enhanced Bakoon AMP-12R; and the DC-coupled very affordable but boffo Job 225 which is a bit less refined but more powerful. You could say that the Japanese challenger had its work cut out for itself.

Round 1.

Wave 40. SPEC vs. FirstWatt. This system came conceptually closest to the designer's own vintage ideal of SET + horns even though my lower speaker sensitivity and lack of front-horn loading still differed significantly. On the one hand this made for a very typical low-power tube-friendly proposition vintage by design. On the other hand it didn't make for a scenario where at least traditionally we'd have expected a class D amp to do well. But times change. Take the forthcoming Greek Kalypso speaker from Rois Acoustics [right]. It will combine a whizzer-fitted Tangband 8-inch widebander with a folded rear horn and built-in PCM-to-PWM true digital amplification by Audio4Soul driven from either a USB or coax input. My recent DIA-250 review had shown how modern high-power class D amps can conjure up valve-reminiscent warmth and fullness into counter-intuitive loads well within the first-watt window. As such my Swiss soundkaos eggs were ideal to test Shirokazu Yazaki's claim that their approach to class D combines the best of traditional transistor and valve topologies. And so too were my simpler-than-triodes SIT1s ideal to juxtapose ultra-refined modern SET sound with specs better than equivalent valve amps. How would the RSA-M3EX strut its stuff in that context?

To simplify A/B/A swaps I wanted to run the RSA-M3EX in amp-direct mode preceded by the same Nagra Jazz preamp which drove the Nelson Pass monos and only subsequently compare the Nagra/SPEC combo to pure spec. Whilst the Jazz into the 35dB-gain Job 225 is dead quiet—the measured S/N ratio of my actual Nagra unit is 114dB—the SPEC in 20dB fixed mode was very noisy in the seat even when the Jazz was set to 0dB gain. In variable mode and with the Nagra set to unity gain, that noise disappeared. I thus would eliminate the Nagra from the go and only assess the RSA-M3EX as an integrated amplifier. In that mode and at the actual volume setting used, the SPEC was dead quiet whenever I paused my source.

The upshot of this juxtaposition against a €12.000 valve preamp + $10.000/pr single-ended transistor monos was a far from wildly dissimilar sound. My twice-priced separates were simply the more informative in the upper half of the sonic spectrum. This translated into more specific depth layering and related separation. I also had the more illuminated upper harmonics and subjectively greater speed with predictable outcomes on transient perception. The Japanese integrated played it darker, heavier and lusher. According to modern parlance and how we use the word 'resolution'—pixel count—it stepped that down. The emphasis instead shifted on something more sumptuous, languorous and rich. In tube terms it was in fact more vintage 300B (Western Electric or Sophia rather than Emission Labs) than the leaner quicker flavour of a 50 or 10Y.

If we drew a horizontal line with end points of fast/lean and relaxed/warm at the left and right respectively, the Bakoon AMP-12R would sit at the far left followed by the Crayon CFA-1.2. The Goldmund/Job 225 would sit between those two but a tier lower to indicate less refinement. The Jazz/SIT1 combo would take up the approximate midpoint. The SPEC then settled down rather farther to the right. How much farther I'd determine vis-à-vis the Gato DIA-225.

Quite a bit. I no longer had the DIA-400 on hand to determine whether that might overlap. That's because the big Dane had struck me as rather more fulsome and lush than its smaller sibling to walk our line way over to the right. With all that implies the RSA-M3EX sounded plainly louder than the DIA-250. It was chunkier. Meatier. At the same time it also projected more forward. This reduced depth and the Gato's more clearly walk-about stage. If we visualize a sea of violins—I was on a kick through various Louis Spohr clarinet concertos on the Hyperion label, with Michael Collins on blackwood—the Gato showed more white caps and ripples. More wind on the surface. The SPEC played it as a more homogenous mass. Less wind. For the clarinet's timbre the difference was akin to that between B-flat and A lengths. The longer instrument sounds darker and warmer.

This gets us directly at the live/playback dichotomy. As reported elsewhere, I'd recently attended our classical music fall festival in Montreux's Stravinski Hall. We'd heard the London Philharmonic under Charles Dutoit with Mussorgsky, Rachmaninov and, fittingly, Le Sacre du Printemps. Sitting in row 7 of the floor's left third the sound there was far closer to what the SPEC now proposed—massive, dark, with more wall-of-sound than vivisectionist staging—than what generally goes for high-resolution hifi sound. With the latter the obvious lack of actual visual data is replaced by quasi-visual playback cues like imaging, performer outlines, halos, pinpoint focus and heightened separation. None of that belongs with un-amplified live music. 1:0 for SPEC. Hurray!

But now we turn tables to inspect the average studio production. Microphones stare down throats and F-holes to capture impressions at pornographic proximities and massively paralleled. Unless we did a Van Gogh on a number of folks simultaneously, no human ears would ever duplicate that. Still with clarinet but now Eddie Daniels andNepenthe on the GRP label, this altered gestalt equalised the game 1:1 for everything left of the SPEC. Obviously close-mic'd multi-tracked recordings make up 95%+ of what we listen to. Now SPEC's readings diverge. They recalibrate such recordings to sound more like an acoustic live concert from a good distance. That's the very essence of this proposition from Japan

The question any buyer has to ask is whether this undeniably attractive makeover has their vote. It's the old beauty versus truth versus beauty is truth conundrum. Here writers must bail. How one decides is entirely personal. It relies on what one uses as reference, what one expects from a hifi and how one weighs tone mass vs. transient speed amongst various trigger points. Based on my exposure to class D sonics and using our earlier graph but now with Hypex Ncore at the center, I'd peg early NuForce well to the left and SPEC far to the right. Most current ICEpower falls between Ncore and SPEC but closer to the latter. Gato's DIA-250 slots between ICEpower and Ncore. AURALiC's Merak monos are the 'poor man's Ncore' to sit right next to NC1200 as I heard it in Acoustic Imagery's Atsah monos. Where does that put SPEC? As Anssi Hyvönen of Amphion put it who provided his speakers to SPEC's Munich HighEnd 2013 exhibit, "it sounded very liquid and for lack of a better word analogue". Spot on!

hat was my fix on the lay of this land. Up next would be the amp's behavior into my already SPEC-voiced Rhapsody 200 towers.

Round 2.

AudioSolutions Rhapsody 200. Using the prior sentence as lead-in segues straight into a predictive answer. Dark, warm, weighty, bassy—my usual brief for the AudioSolutions is "vintage Sonus faber voicing with US-style bass and high dynamics"—looked into the mirror. At lower levels this compounded even more. I wanted for the higher insight and twitchier reflexes of the Meraks. My very best option for the friendly Lithuanian lumberjacks really is the Crayon's whisper-level lucidity. The Bakoon and FirstWatt monos lack power and the latter won't control the underdamped twin ports. The SPEC clearly had no issues with the quite erratic phase/impedance angles of this load. No port boom, no mush. Its own voicing would simply have better complimented a far more neutral Amphion, the recently reviewed very quick Accuton-fitted Albedo Audio Aptica or an equivalent but big Mårten Design or Kharma tower.

Of course that statement betrayed personal bias. Were I a Spendor or Harbeth fan looking to maximize the known virtues of those warm Brit boxes, the RSA-M3EX could be it. Hence Polish contributor Wojciech Pacuła with his Harbeth M40.1 Domestic maxi monitors should be a perfect target-group spec(i)men. No wonder his review of their phono stage netted an award. If we distill our earlier introduction into the sound of vintage paper-in-oil caps, we have another confirmation. In our context none of it comes as a surprise then. 

The thing is, given class D's early criticisms—which haven't applied for a number of years now—it remains good form to reiterate that the breed's pendulum on a whole has since swung in the opposite direction. Whilst especially for Ncore it's swung back a bit again but moved to a higher level, with the M3EX it's stuck in the maximal counter position. As such Shirokazu Yazaki's stated goal has been met. It really is about a powerful dose of classic valve sound. The big difference is cool running power; current-critical load happiness into low impedances; operational silence; and stable performance without the insidiously slow ageing of power triodes and its deleterious sonic effect

With that pegged and the white towers too similar to veer more deeply into the same direction than suited my personal tastes—someone else could feel happily married however—I was curious. How would the Japanese get on with my Boenicke Audio B10? Where the Wave 40 are my Swiss eggs, the B10 are the Swiss slivers. Once you see their span-by-hand width you understand.

Round 3.

Boenicke Audio B10. Unlike the power-matched Crayon which eliminates signal-path capacitors and with it low-frequency phase shift (very good!) to produce a type of 'turbo' effect on these side-firing woofers (too much for my short-wall setup), the M3EX didn't upset the tonal balance. As had been the case on the white towers, woofer control was once again spot on. Whilst not lucid/quick like the Crayon and with rather less energy in the upper octaves, this was as fine a pairing as the eggs had been, extending lower without being plagued by ports for superior sealed bass, the ambient-rich sound favoured by Sven Boenicke—hence his penchant for lateral drivers—responded favourably to the amp's tonal weight. I really suspect Yazaki-San himself would have approved.

So would Kevin Scott, Living Voice designer and author of their superlative Vox Olympian horn speaker. Doubling as the UK's importer of Kondo Japan he favours succulent operatically dramatic sound to detest monochromatic tone colours. I seriously doubt Kevin would ever even consider class D. He's still a PC audio virgin. Just so the M3EX would surprise him just a tick. It really wears its tube lover's heart on the sleeve. As such it could only have been created by a devout SET fanatic. And perhaps the only country open-minded enough on hifi matters in the first place to pursue the strange arc of 300B direct-heated triodes to rapidly switching DirectFet transistors was Japan. So toss the rule book

Wrap.

SPEC's pricing too relies on open-mindedness. EJ Sarmento's mAMP monos are $1.800/pr. Gato Audio's all-in-one DIA-250 is €3.250. Merrill Audio's Hypex-based Thor monos get $4.000/pr. Here and in-between there's plenty of power and refinement to be had without overspending. Mola Mola does push the other direction. But they mean to recoup significant Ncore R&D investment funds. And—or so one imagines at least—they also wouldn't mind to simultaneously move up class D's general perception. Here SPEC sides with Bruno Putzeys. The latter has both name and track record. At least in the West Shirokazu Yazaki has neither. Yet. Being a merely 60wpc class D integrated with a very strange though optional remote makes the RSA-M3EX unapologetically pricey. But if you want what it does—mimic valve sound to this extent whilst throwing in modern power efficiency which SET-ish class A transistor amps certainly don't—then this sober nearly laboratory-named Japanese brand could be the top game in town and play smack in the heart of your most desirable district. In the end it reiterates a hifi leitmotif. It's not topology or parts choices. It's the designer's clear auditory vision which becomes the core determinant over the final outcome. That'swhat bends parts and topologies to its will. Vision is key then. Taken to heart, it becomes clear that class D couldn't be exempt from this rule. If Yazaki-San's results surprise us, it's only because none before have endeavoured to bend switching transistors quite so far in this direction. Henceforth SPEC marks that spot.

………. Sarjan Ebaen

Quality of packing: Very good.
Reusability of packing: Many times.
Ease of unpacking/repacking: A cinch.
Condition of component received: Flawless.
Completeness of delivery: Perfect.

I often get the impression that Japanese high end products have a soul, a part of the designers aura stays under the hood. The SPEC is among these products, Shirokazu Yazaki has me under his spell.
René van Es

REVIEW SUMMARY: The RSA-M3EX.... creating an enormous virtual stage for musicians to excel in solos against other band members or in front of an orchestra. The image reaches from one side wall to the other, and from floor to ceiling, with a back wall that’s no longer audible and a more forward moving sound. But the music doesn’t slam you in the face, the stereo image the RSA-M3EX creates is the one you have been looking for so many years. Time after time instruments and vocalists perform and there seems to be no preference for a particular genre. 
Small jazz combo’s benefit from a system with speed and transparency. The Bobo Stenson Trio’s album Cantando is a good example. Percussion forms an important part of this music and the RSA-M3EX loves it. The drum kit is hit hard, Glockenspiel tingles into the room and cymbals sizzle. Smaller and bigger drums exchange places in an organised barrage. A plucked bass follows the line and piano stands out playing its own solo. The musicians seem to enjoy what they play and the SPEC projects this feeling towards the listener and very soon my feet tap out the rhythm. It makes me realise how natural, rich, pure and musical the sound of this class D amplifier is. The SPEC RSA-M3EX is the first amplifier without the specific class D character that bores me over time, a colouration that turns music into a technical exercise. No manufacturer has overcome this until now, and in advance of a formal conclusion I dare to state that this is the first and only amplifier of this kind that I could live with.

EXTENDED REVIEW: I am always curious about what new brands and/or technologies have to offer, so when I got the chance to hear a SPEC amplifier at home I didn’t say no. I picked the Real Sound Amplifier RSA-M3EX, the middle model in the range. I had not heard of the brand or the designer so took a look on the internet to see what they had to offer, this piqued my interest and in my enthusiasm I changed my normal writing procedure. Usually I start with a description followed by the listening impression, but when a product is very good I start with the sound. Well, the SPEC RSA-M3EX is just such a product.

Matching

Trying to find the best possible match between components is a part of the review process that’s not often told in detail, but sometimes it’s interesting enough to go into. My first set-up was in a smaller room with a pair of Harbeth P3ESR loudspeakers. Playing music was not as spectacular as promised by the distributor and the company leaflets. In fact I could not relate the high price with the performance although I could hear that something special was trying to get out. I missed power, speed and low end energy. Music sounded nice and full of detail, but drums were slow, there were no rumbling bass notes and electronic music had none of its impact. Only the stereo image was very well defined and full of space, putting the accent on the midrange and thus voices. After extended listening I reached the conclusion the speed was not an issue at all and the lack of bass notes had more to do with the chosen loudspeakers than anything else. The Bass might not have been overwhelming, but they came out tight and pure. More pure than results with other amplifiers in the same room and set-up. The perceived lack of drive changed into an admiration of the pure and open sound. With every listening session I got more and more convinced that the SPEC needed far bigger loudspeakers with a higher efficiency to prove its worth.

Who am I, not to move the amplifier into my main listening room and connect a pair of PMC fact.12 transmission line speakers? I enjoyed the SPEC before but this was a new era and I never looked back. The power I missed was there in spades, listening to the sound effects used in movies it was now possible to feel the fear. Bass engulfs the room whilst remaining surprisingly tight, the grip on the loudspeakers showing just how much power this amplifier has to offer. Speed is no longer an issue and drums explode into the room. All my initial reservations about the RSA-M3EX were blown away and it was time to further investigate the real beauty of this integrated amp. The PMC speakers seem to disappear from the room given a decent source and a nice amplifier, there’s no need to close your eyes for that. But the room acoustics and the setting of the speakers in a room that doubles as a space for the family make it a lot harder to create a deep stereo image. Like so many listeners I moved my loudspeakers into a position to get the best compromise and to create a good environment to judge audio components in. In my experience some amplifiers and sources cannot create a deep and wide soundstage in this room, but the RSA-M3EX is just the opposite, creating an enormous virtual stage for musicians to excel in solos against other band members or in front of an orchestra. The image reaches from one side wall to the other, and from floor to ceiling, with a back wall that’s no longer audible and a more forward moving sound. But the music doesn’t slam you in the face, the stereo image the RSA-M3EX creates is the one you have been looking for so many years. Time after time instruments and vocalists perform and there seems to be no preference for a particular genre. Searching for minor limitations I notice that on a CD like Live In The O2 Arena by Katie Melua my own amplifier shows a little more of the atmosphere from the large hall. At the same moment I realise that the combination of speaker and amplifier is one, as slave and master in start/stop behaviour. Some amplifiers tend to create another illusion of space by being a little slower, so which one is right? I do not know and the differences are small.

More music

Small jazz combo’s benefit from a system with speed and transparency. The Bobo Stenson Trio’s album Cantando is a good example. Percussion forms an important part of this music and the RSA-M3EX loves it. The drum kit is hit hard, Glockenspiel tingles into the room and cymbals sizzle. Smaller and bigger drums exchange places in an organized barrage. A plucked bass follows the line and piano stands out playing its own solo. The musicians seem to enjoy what they play and the SPEC projects this feeling towards the listener and very soon my feet tap out the rhythm. It makes me realize how natural, rich, pure and musical the sound of this class D amplifier is. The SPEC RSA-M3EX is the first amplifier without the specific class D character that bores me over time, a colouration that turns music into a technical excercise. No manufacturer has overcome this until now, and in advance of a formal conclusion I dare to state that this is the first and only amplifier of this kind that I could live with.

‘The Bug’ by Dire Straits explodes with hammering percussion, Mark Knopfler in front of the band, drums behind him, guitars to the left and right of the soundstage and backing vocals between the singer and the band. Fast sounding and lacking only a bit of the weight more powerful amplifiers can offer. The RSA-M3EX is about purity, musicality and minimal distortion rather than being a power plant. High efficiency loudspeakers with or without minimalist damping like a pair of Russel K. Red 100 would turn your hi-fi system into a high quality PA system for instance, while my PMCs love and need more power. A Loreena McKennitt performance for German radio called ‘Troubadours On The Rhine’ is extremely well recorded. The dynamic expression within her voice shows the range of the SPEC, shows how low the dynamic noise floor is. Lesser amplifiers modulate the noise with the loudness of the music, making music tiring and restless. The acoustic instruments in the band and McKennitt herself add to the atmosphere and pureness that the RSA-M3EX creates, grabbing the listener’s attention time after time. When the track finishes and the public in the studio applauds a “thank you” from Loreena sounds uncannily real. Unique? No, maybe not, but good proof of the designer’s craftsmanship.

Luo HaiYing sings in Chinese with backing from big drums. These drums need power, despite the SPEC’s 60 Watt rating this is no problem thanks to a heavy power supply and large capacitors, and it produces a wonderful stereo image. Musica Antique Nova by Rachel Podger is even better, her violin almost sings in the listening room. The words subtle, rich and pure come to mind. There’s absolutely no stress in this amplifier, you simply enjoy the performance without any reference the to technology inside the box. It’s hard to listen to what the amplifier does, much easier to enjoy the results. Music is the winner, especially when Dame Kiri Te Kanawa starts singing ‘Madame Butterfly’ accompanied by a large orchestra, the amp’s capabilities seem limitless. Looking for specific class D shortcomings I cannot find any, no matter how hard I try. Is this amp the best ever or do I still want more? Naturally the SPEC does not have the limitless power and authority that my 250 Watt class AB amp delivers, and a bit more air around the musicians would be welcome, just a bit. Why am I looking for shortcomings? Because I do not want to be tempted to buy a SPEC to be honest. Dreaming away again with a piano concert from Mozart played by Kristian Bezuidenhout, it’s a luxury to imbibe music this way.

RSA-M3 EX

The SPEC looks simple with just source, volume and a nice power switch on the front, and inputs, speaker terminals, a switch to illuminate the volume control and a small switch to use the RSA-M3EX as power amp on the back. A 3.5mm bus is available for the two part remote control; receiver and a handset. The bottom of the amplifier is made of wood with integrated feet. The aluminium housing with the spruce base and its maple and hickory feet makes an attractive combination. The amplifier delivers 60 Watts into 8 Ohms and the frequency range resembles that of a tube amplifier, 10Hz – 30Khz ±1dB (6Ω, 1W). Under the hood the SPEC differs from most other class D amplifiers, it has a PWM engine triggering MOSFET switching power transistors, a technique developed by International Rectifier in the US. The power supply has a big R-core transformer and silicon-carbide Schottky diodes. Capacitors are used in a carefully matched mix of electrolytic and paper-in-oil types of different values for the best audio results. The output filter uses a coil specially developed for audio by listening and a combination of paper-in-oil plus silver-mica capacitors, especially made for SPEC by Arizona Capacitors Inc. As SPEC states, the RSA-M3EX is actually made like a tube amp but with class D modules instead of tubes.

Who is SPEC

SPEC designer Shirokazu Yazaki started his career with TEAC Japan, where he stayed for four years developing amongst other things the TEAC A-37300 reel-to-reel recorder, before he went to Pioneer for the following 17 years. After a long stay in Indonesia he returned to Pioneer in Japan where he worked on the CT range of cassette recorders and the ‘legendary’ DV-AX10 DVD/CD/SACD player. His interested in class D was aroused because his old Pioneer colleague Jun Honda works for International Rectifiers producing power management solutions and the pair co-operated in making modules for audio. Yazaki-San has been using single-ended triodes and horn loaded loudspeakers for decades, an enthusiasm inspired by a Jean Hiraga demonstration of Altec horn loudspeakers driven by a DA30 triode based amplifier in 1971. From that moment Yazaki-San became fascinated with the DA30, which he prefers over a 300B, always trying to improve his own designs through listening and research with horn loaded loudspeakers from Altec, JBL and Onken. History was written in February 2010 when the SPEC Corporation was formed by Shirokazu Yazaki and Jun Honda, to bring to the market class D amplifiers that are just as good or even better than the DA30 tube designs that had taken over 40 years to perfect. Yazaki-San points out that the moving coil of a loudspeaker develops energy that returns to the output stage of an amplifier to influence the feedback circuit by creating distortion. In a class D amplifier this energy is absorbed not in a feedback circuit but in the power supply, where it is harmless. Which, he says, is one of the reasons why class D amplifiers sound so pure and clear.

Finally

After an enthusiastic review the conclusion can only be positive for the SPEC RSA-M3EX amplifier. I had to get used to the amp, it first seemed a little plain and underpowered compared to my own amplifiers. An opinion that soon needed adjustment and turned 180 degrees into appreciation of its pure, delicate and undistorted sound quality. Deep bass notes might seem to lack power at first, but soon I found out that bass is so tight, fast and uncoloured that it only attracts less attention. This was even clearer after changing from small monitor speakers to large transmission lines. Also consider the near perfect stereo image of the RSA-M3EX, the spatial sound and the purity of the reproduced music. Every class D amplifier I have heard had a specific class D signature that I could never get used to, I always returned to more conventional designs with a preference for class A. That is until I listened to the SPEC RSA-M3EX, an amplifier that makes me forget the technology and sounds so good that I would like to own one. It’s my first encounter with class D technology that offers high end sound quality in the true sense. I realise I probably make more enemies than friends with these words, so be it. A final word: I often get the impression that Japanese high end products have a soul, a part of the designers aura stays under the hood. The SPEC is among these products, Shirokazu Yazaki has me under his spell.

.......René van Es

You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.
Jeff Day

REVIEW SUMMARY: From the first moment that I saw, touched, and powered my hi-fi systems with Yazaki-san's SPEC RSA-M3 EX Real Sound Amplifier I was deeply impressed with what he has accomplished. There is a certain irresistible 'sensuality' sonically, musically, and even visually to the SPEC RSA-M3 EX Real Sound Amplifier that makes it quite captivating amplifier to listen to music with.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce.

We talked about the SPEC and how its highs were spot-on perfect and natural sounding too, and Julie's vocals were stunningly natural, with absolutely no unnatural sibilance. The bass response was extended and full of nuance, and even though it was only 60 watts, the SPEC could really deliver the dynamic swings when called upon. The SPEC was deceptively powerful, and when loafing along it sounds only about as powerful as my 25 watt MC225, but when you really crank it up it never misses a beat and sounds astonishingly good, even at very loud 'blow out the windows' levels. In short, when we sitting there listening to the SPEC play music we came to the conclusion that it was one of the most perfectly voiced amplifiers we'd ever heard.

Everyone who has heard the SPEC Real Sound Amplifier, including Cindy, has made the comment of how rich and natural the SPEC sounds (in a timbral and tone colour sense), and Cindy added how it drew out many subtleties in the music, and had an ability "to remind you that recordings from your past are 'old friends'". I thought that the last was a particularly interesting comment, because the SPEC does indeed have an exceptional ability to portray music's emotional impact. It reminds you of how you felt when you heard the music for the first time, and it brings back all those feelings in a flood as you listen to the music.

The SPEC's is a very beautiful presentation of tone colour.
If you're interested in an amplifier with the beauty, tone colour, timbral naturalness, and rich stereoscopic musicality of the best vacuum tube designs in a non-fussy and classy solid-state design, I suggest that you listen to the SPEC RSA-M3 EX amplifier. You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.

EXTENDED REVIEW: Most regular readers of Positive Feedback know of my long-time passion for vacuum tube electronics. I've enjoyed the musical prowess and sonic chops of contemporary artisan-designed single-ended amplifiers with various output tubes, like the EL84, 45, 2A3, 300B, F2a, and 845 output valves; as well as inspired push-pull amplifiers using KT88, EL84, KT66, EL34, KT90 outputs, and probably some others I'm forgetting at the moment.

Lately I've been reveling in the musicality of vintage audio electronics with their classic circuits, like the McIntosh MX110Z tuner/preamplifier (27 vacuum tubes!), the McIntosh MC240 stereo and MC30 monaural amplifiers (6L6GC outputs), and McIntosh MC225 stereo amplifier (7591 outputs). Célébrer le tube à vide!

However, when I reviewed the ASR Emitter II Exclusive Version Blue solid-state amplifier from Germany back in Issue 66 I found out that valves weren't the only path to sonic nirvana, and that 'Big Blue's' sonics & musicality were superb on my equally big Duelund-crossover'd customized Tannoy Westminster Royal SE loudspeakers.

I learned the audio lesson that while parts choice does make an important difference in performance, it is the 'enlightened ear' of the talented designer that determines the ultimate musical performance of an audio amplifier, whether it contains vacuum tubes or solid-state devices.

The High-Fidelity Adventures of Mr. Shirokazu Yazaki
A case in point is the SPEC RSA-M3 EX Real Sound Amplifier from the 'enlightened ear' of Mr. Shirokazu Yazaki in Tokyo, Japan, that sounds shockingly good by any musical or sonic measure.

From the first moment that I saw, touched, and powered my hi-fi systems with Yazaki-san's SPEC RSA-M3 EX Real Sound Amplifier I was deeply impressed with what he has accomplished. There is a certain irresistible 'sensuality' sonically, musically, and even visually to the SPEC RSA-M3 EX Real Sound Amplifier that makes it quite a captivating amplifier to listen to music with.

Before I get too carried away telling you about the SPEC RSA-M3 EX Real Sound Amplifier, let me back up for just a moment and tell you about the man behind it, Mr. Shirokazu Yazaki (second from the left in the photo below). I have found the story of Mr. Shirokazu Yazaki's audio journey during our conversations to be quite fascinating, and I'm hoping I can relay that sense of intrigue to you, and why I think his story is important.

First of all, Mr. Shirokazu Yazaki has been a successful professional audio designer in Japan for over 40 years, and has been involved in the design of many fine audio components from some of the foremost Japanese electronics companies during that time. Yazaki-san fondly reminisces about a few component design high points he was involved with, like the TEAC A-7300 semi-professional open-reel tape recorder while he was at TEAC, or the Pioneer CT-95 / T-1100S cassette recorder as a design team leader & manager at Pioneer in their cassette recorder engineering department, or the Pioneer DV-AX10 universal disc player as the general manager for the Pioneer DVD engineering department.

Those of you with a detailed historical knowledge of audio will remember the highly regarded TEAC A-7300 reel-to-reel; the Pioneer CT-95 / T-1100S cassette recorder, which was considered superior to even the legendary Nakamichi Dragon; and the Pioneer DV-AX10, which was the world's first true universal disc player capable of playing CD, SACD, DVD and DVD-A with both high audio & video fidelity.

Towards the end of his career at Pioneer, Mr. Shirokazu Yazaki was put in charge of the Pioneer research & development center, where he first came into contact with a prototype class-D switching amplifier in 2006.

Now Back To The Beginning
Ok let's stop right here for a moment. Now we are going to journey back in time 40 years or so to 1971 when Mr. Shirokazu Yazaki first started his professional audio design career at TEAC, a young man fresh out of the university with a mechanical engineering degree.

There were events occurring during that time that would mark it as one of the defining periods of audio history, which would send ripples of inspiration through time to the future to spark an audio revolution that changed the way that many of us today think about what's possible in high-performance audio.

Over the years as an audio writer, it has been a great pleasure for me to interview a number of eyewitnesses who were involved from the beginning of that important period, like Mr. Shirokazu Yazaki, and to tell the story of how events unfolded, and how those events would come to shape the future of enthusiast audio, including my own enjoyment of music today.

While Japanese audio enthusiasts were familiar with the excellent American vacuum tubes from Western Electric, RCA, GE, etc., they didn't have a lot of access to European and British vacuum tubes until towards the end of 1960s, when a most important event occurred with French audio connoisseur Jean Hiraga (of L'Audiophile fame) starting to import European & UK vacuum tubes to Kobe, Japan.

Magazines like MJ and Radio Engineering were publishing do-it-yourself (DIY) articles about building vacuum tube amplifiers, including some using those 'new' European & UK vacuum tubes from Jean Hiraga, which were embraced by the creative 'underground' audio movement in Japan. There were a lot of really interesting designs taking shape around the vacuum tubes that were available from America, Europe, and the UK, and in particular around the ascension of directly heated single-ended-triode power (SET) amplifiers that were intended for use with high-sensitivity horn loudspeakers.

The Tokyo Audio Fair of 1971 featured a number of those vacuum tube amplifier designs, and notably the combination of DH-SET amplifiers driving high-sensitivity Altec A-5 loudspeakers, which wowed show goers with their superlative music-making ability, including our young Mr. Shirokazu Yazaki who had just started his career at TEAC.

Now the young Mr. Shirokazu Yazaki who went to work at TEAC was also an audio enthusiast & music lover who particularly enjoyed listening to jazz, so in 1971 when Yazaki-san went to the Tokyo Audio Fair he was impressed by the intense musical satisfaction that could be realized by listening to music with DH-SET amplifiers powering high-sensitivity Altec horn loudspeakers.

Excited by the possibilities of that 1971 Tokyo Audio Fair, Mr. Shirokazu Yazaki embarked upon what would become a life-long journey of assembling & refining his personal high-fidelity music system, first by constructing his own DH-SET amplifier, then by building and customising a Marantz 7 kit preamplifier, and over time developing his Altec & Onken-based horn loudspeakers.

In 1972 Yazaki-san began building his own SET amplifier after reading an article in the June issue of MJ magazine by a Mr. Anzai about building a simple GEC DA30 SET amplifier. Yazaki-san completed that first SET amplifier in early 1973, using the American Western Electric 310A as the driver, a Western Electric 274B as a rectifier, and the English GEC DA30 as outputs (the DA30 is less well known in the West, than say the 300B is, but it is held in extremely high regard by aficionados within the Japanese DH-SET scene, but they are rare and difficult to come by these days).

Mr. Shirokazu Yazaki told me that he has continuously improved his DA30 DH-SET stereo amplifier over the years, and the combination of Western Electric 310A driver, Western Electric 274B rectifier, and GEC DA30 outputs provides the most beautiful tonality he has every heard from an amplifier. Even though they were both capable of putting out 8-9 watts, Yazaki-san told me he selected the GEC DA30 over the Western Electric 300B for his amplifier because it had superior high-frequency response. He also went on to say that the oldest version of the Western Electric 310A, the 'mesh shield' that was produced in the 1930s & 1940s, was critical to getting the best sound. He thought that later versions of the WE 310As sounded rougher & less natural compared to the smooth & natural sounding original 'mesh shield' version. Yazaki-san also told me that the 1940s 'engraved' version of the Western Electric 274B rectifier expressed tonal colours better than all the other rectifiers he had experimented with. Compared to the 'engraved' version of the 1940s WE 274B rectifier, he found the Telefunken GZ34, Philips original GZ34, Mullard GZ37, GZ37 big bottle, RCA5R4GY, Western Electric 422A, etc., while excellent rectifiers, all bleached the tonal color to some extent.

The Western Electric 310A driver, Western Electric 274B rectifier, and the GEC DA30 outputs resulted in a rich midrange, beautiful tone, and a powerful upper bass that combined to give exceptional musicality.

Shortly after completing his DA30 DH-SET stereo amplifier Mr. Shirokazu Yazaki began building up his horn loudspeaker system. He started his loudspeaker system with a pair of 1960s vintage Alnico-magnet Altec 414A woofers in 1973, and then ordered Mr. Koizumi's Onken OS-NEW500MT drivers with matching SC-500WOOD wood horns in December of 1973, which were delivered in 1975. In 1977 Yazaki-san added Onken OS-5000T Esprit tweeter to complete his horn loudspeakers.

In 1979 when Marantz released the Marantz 7 in kit form, Yazaki-san bought the kit and built it up with better parts. Yazaki-san said he learned a lot about getting good tone modifying his Marantz 7 kit with different components, and he has made continuous improvements to it to the present day.

Mr. Shirokazu Yazaki described to me the sound of the audio system he built as being transparent, beautiful, rich, and dynamic, but most importantly it possessed "real stereoscopic sound full of musicality."

A Quick Lesson in Big DH-SET History
Now let me diverge slightly from Mr. Shirokazu Yazaki's story for just a moment so I can connect the dots of audio's 'big DH-SET history' for you by telling you how the Japanese DH-SET audio culture and Jean Hiraga's importing vacuum tubes to Japan would eventually trigger a change in Western audio culture, and then we'll get back to Mr. Shirokazu Yazaki's story and I'll explain how it all connects together.

Japanese audio enthusiasts like Mr. Yazaki-san who noticed how good DH-SET amplifiers were both musically & sonically started buying up vintage American & English vacuum tubes like the Western Electric 310A & 274B and GEC DA30, and vintage speakers that were designed to be used with low powered vacuum tube amplifiers (like the Tannoy series of Dual Concentric™ speakers and enclosures, and the Altec Voice of the Theatre loudspeakers (Altec was a spin off company of Western Electric incidentally)).

Those Japanese music lovers & fine audio constructeurs of vacuum tube circuits noticed how good those types of hi-fi equipment were at portraying the timbral & color aspects of the music, and like Mr. Shirokazu Yazaki, those enthusiasts continued to develop and refine those systems so that their presentation of music's timbral and color elements were truly profound, and their listening emphasis was expressed through equipment choices that maximized those qualities to result in a very different presentation of music than many listeners in the West were used to at the time.

However, once a fire is lit, you really can't keep it hidden for long, and word about the amazing musical realism attained by combining those highly refined DH-SET amplifiers with highly sensitive loudspeakers soon got out to those in the West who had ears to hear, like Jean Hiraga.

Due to his importing vacuum tubes to Japan, Monsieur Hiraga was among the first in the West to become aware of this new exotic DH-SET audio trend in Japan. He and his French enthusiast audio magazine L´Audiophile had discerned the importance of this aroma of music wafting in on the breeze from Japan and responded by opening a shop in Paris to do demonstrations of this new-old style of music listening.

In 1986 L´Audiophile demonstrated a 300B DH-SET amplifier at their store in France that signaled the birth of the DH-SET movement on French soil. The musical realism, the exquisite textures & colors, and the dynamic truths that L´Audiophile achieved so easily in their demonstrations using DH-SET amplifiers, Altec-Onken & Voice of the Theatre loudspeaker systems, and playing records on a Platine Verdier turntable, impressed a lot of people, and the SET, horns, and vinyl approach to musical nirvana started to go viral, working it's way into Germany.

The founder of Auditorium 23 in Germany, Keith Aschenbrenner, told me that after hearing the L´Audiophile system during this period, he thought that what Philippe, Jean, and Gerard were doing was remarkable, and their demonstrations marked a major milestone in musical realism in audio. Keith told me, "It was quite an education to hear that new 300B SET approach to amplification. When we got that first 300B SET amplifier in our shop, connected it to the Voice of the Theatre loudspeakers, it was just like a musical Christmas present. In the beginning, we handled it like Sunday shoes. The harmonic integrity and musical realism were astonishing. We went from using it for special demonstrations only to using it every day. Going back to our other equipment became so hard that we just gave up on it and stayed with the 300B."

A little while later the single-ended-triode virus made it to the North American audio scene when Noriyasu Komuru started building DH-SET amps, as did Gordon Rankin, and Don Garber. The DH-SET fires had begun burning in the consciousness of audio enthusiasts across North America, where whispers from the audio underground were heard to say "DH-SETs live again, and they can bring your music back to life." The SET resurrection fires raged on through time and place to a point where most contemporary enthusiasts now consider the DH-SET amplifier to be a normal part of the Hi-Fi scene.

Now Back To The Future
That's right, the DH-SET & horn loudspeaker revival around the world that many of us are enjoying today all started with the 'enlightened ear' of audio enthusiasts in Japan, like Mr. Shirokazu Yazaki, and others.

So now I want you to consider this intriguing scenario and its implications: In parallel over the last 40 years, Mr. Shirokazu Yazaki spent his workdays designing audio components professionally for two of the most influential Japanese audio electronics companies, TEAC and Pioneer, while during his personal time he was building & optimizing each component in his artisanal DH-SET & Altec-Onken horn loudspeaker audio system for his personal enjoyment of music.

Those two parallel audio themes in Mr. Shirokazu Yazaki's life intertwined & collided in time in October of 2006 when Mr. Nishimura-san from International Rectifier in Japan demonstrated a prototype class-D switching amplifier at the Pioneer research & development centre that Mr. Shirokazu Yazaki managed.

Mr. Yazaki-san told me that while the prototype class-D amplifier's sound quality was not as sophisticated as the best DH-SET vacuum tube amplifiers, he was shocked by its rich & musical sound, and he thought that those particular new class-D power devices it contained represented development & optimisation possibilities as exciting for audio enthusiasts as those during the time of the rise of the DH-SET culture in Japan back more than 40 years ago now.

Two months later, in December of 2006, Mr. Yazaki-san was in Los Angeles meeting with the designer of the prototype amplifier's impressive new generation of class-D power devices, Mr. Jun Honda, at International Rectifier. Mr. Honda-san was a former junior colleague of Mr. Yazaki-san's at Pioneer, and a personal audio friend, and after leaving Pioneer Mr. Honda-san had immigrated to the States where he went to work for International Rectifier (IR). Honda-san had been working at IR for about six years when he developed the new class-D power devices that Mr. Yazaki-san would hear in the prototype class-D amplifier that Mr. Honda-san & Mr. Nishimura-san had developed together, and which was then demonstrated by Mr. Nishimura-san at the Pioneer R&D center a few months before.

Impressed with the possibilities represented by the new class-D power amplifier developed by Mr. Honda-san & Mr. Nishimura-san, Mr. Yazaki-san began developing a class-D amplifier of his own based on Mr. Honda-san's new generation of class-D power modules, using his own artisanal Western Electric 310A, Western Electric 274B, and GEC DA30 DH-SET amplifier as the voicing reference.

His goal was to apply the same sort of attention to detail to the class-D amplifier he was building with Honda-san's new generation of class-D power modules that he did to his own DH-SET amplifier, desiring to approximate as closely as possible that amplifier's rich midrange, beautiful tone, and exceptional musicality.

Mr. Yazaki-san was so pleased with the way his class-D amplifier turned out he decided to build one for his good friend to enjoy, Mr. Nakamura-san. In 2009 Mr. Yazaki-san had Mr. Nakamura-san's new class-D amplifier finished and ready to go, and it turned out to be so impressive, that quickly on the heels of that, on February 6th, 2010, SPEC Corporation was founded.

A New Year's Eve to Remember
Mr. Yazaki-san enjoys building amplifiers for his friends, and he also built a beautiful pair of GEC DA30 monaural amplifiers for his good friend Mr. Ookubo-san (below left). Mr. Yazaki-san told me the story of the gathering of his audio friends on New Year's Eve to listen to the new monaural GEC DA30 amplifiers he built for Mr. Ookubo-san, and the class-D amplifier he had built for Mr. Nakamura-san

When Mr. Yazaki-san and his friends listened to the new GEC DA30 monaural amplifiers (below) they were all so moved by the music that it was truly a transcendent experience for them. He told me that what they experienced was so spectacular that it was hard for them to put into words, "We felt that the stereophonic sound we heard had reached an ultimate revel, and we were fascinated with and intoxicated by the music. The sound was transparent, beautiful, rich, and dynamic, and in the truest sense was "real stereoscopic sound full of musicality"."

Yazaki-san had told me that his good friend Mr. Ookubo-san had always enjoyed hearing his GEC DA30 amplifier in his system so much that he desired one of his own. "He loves so many kinds of music from classical to jazz, and had been so moved every time when he heard the sound of my old system with my aged DA30 stereo amplifier that I built up in early 1973, 40 years ago now, that he desired a DA30 amplifier of his own."

Yazaki-san told me that all the improvements he had made to his DA30 stereo amplifier over the years had resulted in a tonal quality that had reached an incredible level. He also told me he was a little worried about finding the exact tubes he needed to replicate that tonal quality, like the 1930s Western Electric 310A 'mesh shield' that he used for the inputs, or the 'engraved' early 1940s version of the Western Electric 274B for the rectifiers, which both had superior tonal color compared to later versions, but were really hard to find outside of a museum.

Mr. Ookubo-san was able to locate all of the best tubes Mr. Yazaki-san needed for the circuits, and he was able to start designing and building the monaural amplifiers. Mr. Yazaki-san also wanted to make Mr. Ookubo-san's monaural amplifiers as beautiful as they were good sounding, and he told me, "I thought that the appearance was an important matter for these amplifiers full of valuable vintage tubes. So I wanted to use and reproduce the beautiful color of "Altec Green" for the chassis, the same hammertone enamel paint used in my aged woofers' frames (the color used on the Altec 414A made in the 1960s), so I imported the paint from USA."

Mr. Yazaki-san developed the drawings of the chassis he desired for the amplifiers, and Mr. Yokoyama-san, a specialist from Valve's World, built them up for him using a combination of aluminum and wood. Mr. Yazaki-san told me, "Thanks to his artisanal approach to the chassis, everyone commented on how splendid the Altec Green colour was, how beautiful the monaural amplifiers turned out, and how fabulous the craftsmanship was."

Mr. Yazaki-san told me, "Of course Mr. Ookubo-san was thrilled with the extraordinary sound, musical performance, and the appearance of the monaural amplifiers. I'm also so happy that I could pour all of my skills and experiences from the last 40 years into building up these monaural amplifiers for Mr. Ookubo-san."

Mr. Yazaki-san went on to tell me that the maximum power output of his DA30 stereo amplifier was only in the range of about 8 to 9 watts, and he used it to drive his 105dB sensitive mid-horns and tweeters (Onken OS-NEW500MT drivers with SC-500WOOD horns, and Onken OS-5000T Esprit tweeters). To power his vintage Altec 414A woofers (500 Hz on down), Mr. Yazaki-san built a push-pull triode amplifier of his own design to complete the amplification of his Altec-Onken loudspeaker system.

He told me, "All those present for the New Year's Eve audio celebration felt that the combination of Mr. Ookubo-san's new DA30 monaural amplifiers (foreground below) and my old Altec-Onken horn speaker system was supreme."

Then they swapped out Yazaki-san's triode bass amplifier and substituted the class-D amplifier he had built for Mr. Nakamura-san (bottom right above). "We wanted to know how well the class-D amplifier would be able to drive the powerful vintage woofer, and how its tonal balance would compare to the tonal quality to Mr. Ookubo-san's new DA30 monaural amplifiers."

He went on to tell me, "The precise low-range control and vivid tone color of the mid to low-range really impressed us. We could not believe how good the sound was with the combination of these two very different types of amplifiers, one was the simple but oldest circuitry tube amplifier, and another one was new-design class-D amplifier. We couldn't believe how good this strange combination was, but it was a fabulous thing for us."

Mr. Yazaki-san told me how excited they were, "Because this demonstration had showed us that the newest class-D amplifier could be a real successor of vintage direct-heated single-ended-triode type of musical performance. We are all convinced that in the near future all music lovers who enjoy DH-SET type sound will enjoy the extraordinary fine tonal character and musicality of this newest design class-D amplifier, and at reasonable prices for an artisanal amplifier. Also, the additional power of the class-D amplifier with its precise control of the low-range is surely beyond any type of past amplifiers! My dream has come true!"

Why are these stories important?
You're probably wondering why I've taken so much time in this article to tell you in detail all about these interesting audio stories of Mr. Yazaki-san and his friends. After all, haven't class-D amplifiers been around for a while now, and aren't they already starting to proliferate? Well, yes they have, and yes they are.

In fact, I heard my first class-D amplifier back in 2004, and there were commercial high-performance audio offerings of class-D amplifiers in the USA as early as 2002, and maybe a little before that. I fondly remember listening to the little class-D Sonic Impact T-amp with my audio pals Pete Riggle, Bill Van Winkle, and TASmanian-devil Stephæn Harrell (Stephæn wrote for TAS before he wrote for 6Moons), when they had stopped by for an impromptu visit and listening session back in 2004.

We were/are all fans of vinyl front ends driving DH-SET amplification to power horn-loaded loudspeakers, and yet we were all quite astonished that a class-D 'toy' amp like the Sonic Impact T-amp could sound as good as it did. As I mentioned in my 6Moons T-amp article back then, my friend Bill Van Winkle is a sightless master piano restorer who lives the absolute sound. At the time, Bill was working on restoring a beautiful 100-year old walnut grand piano that was so gorgeous that I was tempted to empty out my life savings to buy it - and I don't even play piano! You know a guy like Bill has got his priorities straight when he has more pianos than he has audio components.

We had all been listening to the Yamamoto 45 SET and a variety of other single-ended amplifiers at the time. Imagine that you were there listening with us, and then I blindfolded you and slipped the class-D T-amp into the system and asked you to comment on its sound ... what do you think you'd say? I guess it'd be pretty close to what Bill Van Winkle said: "Its sonic signature reminds me most of the Yamamoto 45. It is clean sounding with lots of detail and decent rhythm and pace. Not quite as smooth and musical but very good."

I'd like to point out to you that Bill Van Winkle's reaction was similar to Mr. Yazaki-san's reaction upon hearing the prototype class-D amplifier at the Pioneer R&D facility in 2006. Those two very different approaches to class-D amplifiers evoked comparisons to DH-SET amplifiers in those two 'golden-eared' gentlemen when they heard them.

So what's the big difference between back in 2004, and now with other commercial class-D amplifiers, from what Mr. Yazaki-san is doing with class-D amplification today?

The class-D amplification environment of today is similar to the vacuum tube environment back 40 years ago or so when the DH-SET movement started in Japan. Really? Yes, really. Forty years ago there were commercial vacuum tube amplifiers available, and DH-SET amplifiers like the now legendary American Western Electric 91A (300B) had been around since 1935 (and the 92A even earlier).

So what were those Japanese audio enthusiasts doing that was so different in the sea of vacuum tube amplification that were available to them then that caused Monsieur Jean Hiraga to go "Whoa!" when he heard their hi-fi systems? What was it that was different about what they were doing compared to everything else out there at the time?

The Enlightened Ear
I believe that much of the difference boiled down to this: Japanese audio enthusiasts who were developing those DH-SET amplifiers 40 years ago were uniquely prepared by their culture to listen for different parameters of musical performance than was typical for most Westerners at that time, and they developed DH-SET amplification (and assembled audio systems) that optimized those musical elements.

I will point out that people in different cultures around the world listen to music differently, by placing more attention on listening to certain aspects of music's attributes than is common to other cultures. It might seem surprising, but the truth is that not everyone hears things the same way as you or I do when listening to the same piece of music.

For example, in most of Western culture, the conventional way of listening to and interpreting music is for the ear to focus in on pitch and harmony first. Yet in the traditional cultures of Turkey, Africa, and Japan, the listener's ear focuses in on the textures and colours of the music first—that's called 'timbral listening' by ethnomusicologists.

I think that those Japanese audio enthusiasts developing DH-SETs and building Altec-Onken horn loudspeaker systems were more discriminating when it came to listening for the timbral aspects of music because of the tradition of timbral listening in their culture, and those particular components they chose & refined excelled in reproducing those timbral traits. Those enthusiasts continued to develop and refine those systems so that their presentation of music's timbral and color elements were truly profound, and their timbral listening emphasis was expressed through equipment choices that maximized those qualities to result in a very different presentation of music than many listeners in the West were used to at the time.

So I think what happened as this new-old timbral way of listening to music was introduced to the West, was that it was mistakenly interpreted as being about the unique sound of horn loudspeakers combined with DH-SET amplification and vinyl front ends, but in reality it was an introduction to a beautiful expression of a particular culture's unique way of listening to music, timbral listening, and that when some of us in the West heard it for the first time it was a true 'aha moment' that changed the way we thought about listening to music.

The whole point of what I've been getting at by relaying these stories to you is that I think the same thing that happened 40 years ago with vacuum tubes & timbral listening in the development of DH-SETs in Japan is now happening again with the latest generation of class-D amplification devices & timbral listening in Japan. I think we may very well be living in another 'big' aha moment in audio history comparable to the one that happened with the DH-SET movement in Japan now over 40 years ago, but this time using class-D amplification devices.

I think that the superb tone colour and rich timbral texture presentations are part of the reason that vacuum tube Japanese audio equipment from Kondo or Shindo, for example, have generated such a dedicated following among music enthusiasts, and those same aesthetic musical sensibilities that have informed their designs are now present in class-D amplification from Mr. Shirokazu Yazaki. So while the 'media' of their art forms differs in the amplification devices used, the beauty, tone color, timbral naturalness, and rich stereoscopic musicality that informs their designs is present in abundance in the SPEC RSA-M3 EX amplifier of Mr. Yazaki-san just as it is in those esteemed vacuum tube designs.

So here once again we have the 'enlightened ear' of a talented audio designer that has recognised and refined the possibilities of a promising amplification device, and this time it is in the form of a class-D amplifier instead of a directly heated single-ended-triode.

Let the fun begin!

The SPEC Corporation
First let me introduce you to the people behind the SPEC RSA-M3 EX Real Sound Amplifier.

All of the members of the team contributing to the design of SPEC RSA-M3 EX Real Sound Amplifier use to work as part of the professional design team at Pioneer in Japan.

Mr. Yazaki-san told me, "Banno-san is not only a skilful engineer but also a musician who plays the piano, and is now learning the cello too. When he was working at Pioneer he was the authority of the optical disk player, such as the LaserDisk, DVD, and Blue-ray disk players. Banno-san and Yamakawa-san have very sensitive hearing. I'm so lucky for having such a good team!"

Mr. Banno-san is on the left in the photo above with Mr. Yoneda-san, whom about Mr. Yazaki-san says, "He is an expert engineer working in Nichicon, a very famous electrolytic condenser maker in Japan. His hearing is so sensitive that the sound of our products owes much to his development work for Nichicon. We are so lucky for getting the best capacitors in the world, Nichicon in Japan, and Arizona Capacitors, Inc. in the USA, and further more to the supremely good sounding Mica capacitor!"

Mr. Yazaki-san went on to say, "Honda-san has a genius for audio circuitry. He has immigrated to the USA with his family, his wife and three children, and has been working at International Rectifier since 2001. Honda-san developed the excellent new class-D solution, and the prototype amplifier with Nishimura-san, and now has launched a new audio business sector for IR, and is its director. When he lived in Japan, he used to come to my house and we enjoyed listening to jazz music together with my old tube and horn speaker system, so he has a lot of experiences of splendid direct heated single ended triode sound. We are still good friends even though he lives beyond the Pacific Ocean in Los Angeles, California."

                                                  The SPEC RSA-M3 EX Real Sound Amplifier

The SPEC RSA-M3 EX Real Sound Amplifier is a 60-watt (8 Ohms) per channel stereo integrated amplifier with three RCA inputs and one XLR input. With a flip of switch the SPEC RSA-M3 EX can also be used as a dedicated amplifier with a preamplifier. 

Here's an interesting observation: The new-generation class-D amplification modules developed by Mr. Honda-san for International Rectifier specifically for high-performance audio use were informed by that same sort of listening insight into tone color and timbral textures that he and Mr. Yazaki-san enjoyed while listening to jazz on Yazaki-san's DA30 DH-SET stereo amplifier and his Altec & Onken horn loudspeaker system.

Mr. Yazaki-san says, "By employing Mr. Honda-san's latest developed class-D amplifier devices, the power MOS-FETs achieve highly accurate current switching in the power stage, and a high-voltage gate driver IC with excellent time-axis control maximizes the ultimate PWM switching. The exceptional performance of these class-D devices ensures ultimate real sound with quality damping in the mid to low ranges even when driving low-efficiency speakers. Furthermore, the sweet and rich tonal character in the mid to high ranges of the amplifier is almost like the tone of the very best triode tube amplifiers."

The audio board in the SPEC RSA-M3 EX is located at the final stage of the amplifier just before speaker terminals, and consists of a low-pass filter and a snubber circuit (an energy-absorbing circuit used to suppress the voltage spikes when a switch opens). Mr. Yazaki-san told me, "This filter and the circuit are very important for the sound quality. In other words, M3EX's tonal quality depends largely on the parts used in these circuits."

"You can see two hermetic oil-filled capacitors on the audio board made for us by Arizona Capacitors, Inc. Yes, these capacitors are custom-made for us and each capacitor has a different tonal character. One has a beautiful mid-to-high end, and the other has a rich mid-to-low range like a vintage capacitor."

"And another special quality part are the two little black cubic boxes you can see on the audio board, which are custom Mica capacitors that are custom made for us in Japan, and they are one of the best sounding capacitors of all ages for a signal capacitor. These days Mica capacitors are so rare to have, but they are wonderful sounding, highly transparent like a blue sky. The clarity of the Mica capacitors combined with the rich sound of the oil-filled capacitors gives the really incredible deep tonal character to the SPEC RSA-M3 EX."

"The ideal sounding capacitor does not exist so we blend these different types of capacitors to get our favourite sound. The same is true for our power supply.

In our DC power supply we use the latest Silicon Carbide (SiC) Schottky diodes, which provide a powerful and noise-free sound. We select the diodes by ear for the best sound, and we choose only best ones, often only one out of ten that we listen to. The efficiency of class-D amplifier is far higher than any other semiconductor amplifier, and it runs up to 96% efficiency at full power. A traditional class-A or class-AB amplifier's final stage efficiency is only 20 to 30%. So these types of amplifier need big heat sinks. Our class-D amplifier is very sensitive to the quality of the power supply. Yes, we could say, the quality of the power supply determines directly the final sound quality. So we blended three types of capacitors, and this parallel connection of the capacitors reduces ESR (equivalent series resistance) in the entire range, which leads to a clear and also powerful sound. The oil-filled capacitors could compensate the mid to high range characteristic of electrolytic capacitors and bring out high speed, rich tonal character."

Our power switch is a type of switch used only for professional-use, for example in aircraft. It has high capacity and is very rugged."

I would also add that it is a very interesting power switch to use, and it has a very deluxe feel to it. It sure is a lot nicer than any of the switches in the old Cessna 150 aircraft I owned as a kid! To turn on the amplifier you first pull the spring-loaded locking switch out, and then switch it into position, and it locks in place. I've never encountered one like it before.

 "The selector switch is made in Japan for use in instruments for the communications industry." 

The wires are Belden 1503A, which we found in our evaluations to be one of the very best cables for inner signal use. The switch is hand-assembled by a technician, and is a higher-quality successor to the style of switch assembly used in the Marantz model #7 for input selection."

"The SPEC variable resistor is not your usual variable resistor, and no signal current flows in this variable resistor. It only works as a position-sensitive detector, and there is a very precise electronic volume device in our class-D amplifier unit that decides the gain of amplifier according to the information from this detector. We regard this variable resistor as very important for the tactile feeling of adjusting the volume, so we custom order it with a special curve and torque for just the right feel. The resistor is sealed for long-term reliability."

"The input selector and volume knobs are made for us in Japan."

The base of the RSA-M3 EX 's chassis is made of a solid laminated panel of European spruce from Austria. Mr. Yazaki-san says, "Spruce has long been used for the top plate of stringed instruments and the soundboard of pianos, and is known as a material with excellent sound quality that provides quick vibration transmission and moderate damping."

I thought that the spruce base for the RSA-M3 EX's chassis was intriguing, and I don't recall seeing anyone doing that before. My Gibson Advanced Jumbo guitar has an Adirondack spruce top and Brazilian rosewood back and sides (above), and it sure sounds fine. Also, in the photos of my listening / living room in my various articles at Positive Feedback Online you'll notice that all my audio equipment is on natural wood supports, like my solid walnut rack for my vintage McIntosh gear and turntable, including my Duelund external crossovers, and all the Sablon Audio Panatela speaker cables. Wood just makes audio gear sound better.

Mr. Yazaki-san, went on to say, "The combination of this material with the rigid steel chassis produces a rich and pleasant sound. The footers on the bottom of the wood base are a combination of pure painted maple from Hokkaido, Japan, and hickory from North America. Maple has excellent strength and is used in combination with spruce for the sides and backs of stringed instruments. Hickory is a hard material that absorbs impact well and is used for drumsticks, for example. The maple and hickory moderates the resonance of the spruce to help provide a rich musicality."

From the development of the class-D amplifier modules, to the selection of every single component that makes up the SPEC RSA-M3 EX Real Sound Amplifier, Mr. Yazaki-san and the entire SPEC team paid serious attention to voicing the amplifier to sound as musically satisfying as the transparent, beautiful tone colour, rich, and dynamic nature of the DA30 DH-SET reference amplifier.

                                                   The SPEC RSP-901EX Real Sound Processor

In addition to the SPEC RSA-M3 EX Real Sound Amplifier Mr. Yazaki-san also sent along a pair of the SPEC RSP-901 EX Real Sound Processors for me to listen to. The retail price for the SPEC RSP-901Real Sound Processors will be somewhere around $1000 USD a pair by the time they reach your dealer's showroom.

The SPEC RSP-901 EX Real Sound Processors are designed to reduce the fluctuations of loudspeakers' impedance over the frequency spectrum, while absorbing the return current from the speaker and its potentially deleterious effect on amplifier performance via a network of inductors.

The binding posts of an RSP-901 EX,onnects to the loudspeakers binding posts via a speaker cable 'pig-tail' (below on my Harbeth Super HL5s). 

Mr. Yazaki-san told me that using the RSP-901EX can result in a pretty dramatic improvement to the sound quality of a pair of loudspeakers, by making them sound more clear, natural, and musical throughout their range.

Inside the spruce enclosure are hand-picked components for the best sound quality: "…state-of-art hermetic seal oil-filled capacitor, named "Green Cactus" series made in USA, by Arizona Capacitors, Inc. …the resistor adopted… which has the smoother and more open air character…" and "…please pay attention to the appearance of RSP-901EX. It's like a jewelry box made of real spruce from North America with string instrument's color."

The idea for the RSP-910 EX came from an article in MJ magazine by Mr. Yasui in 1971 about impedance correction for loudspeakers. The relationship between a loudspeakers impedance variation with frequency, the resulting return electromotive force from the speaker to the amplifier, and the output of an amplifier driving the speaker based on the input signal, is a fairly complex relationship. It's a lot of variables for an amplifier to deal with, and a lot of things that an amplifier has to react to and get right for the best sound. Mr. Yazaki-san told me that solid-state amplifiers are more affected by this complex interaction than are vacuum tube amplifiers, but both can benefit from installing the RSP-910 EX, which minimizes the effects of the loudspeakers' impedance variation with frequency, and the resulting return electromotive force from the speaker, making life easier on the amplifier, so that it performs better.

Review Systems
For this review I used both of my current hi-fi systems, the smaller Harbeth Super HL5 and Leben based system I use in my listening/television room, and my Tannoy & vintage McIntosh system that I use in my larger living room space. They're both fantastic systems for the music lover!

In my small-room system I use Harbeth Super HL5 loudspeakers on Skylan 18-inch stands, Acoustic Revive Single Core speaker cables, the Leben CS-600 integrated amplifier, Acoustic Revive Single Coreinterconnects, the Leben RS-30EQ phono equalizer, an Auditorium 23 '103' style step-up transformer, Acoustic Revive Power Reference AC power cords, a VPI Classic turntable fitted with an EMT TSD-15 phono cartridge, an Oppo BDP-83 Blu-Ray player, an Apple TV & Roku for streaming duties, and a 42-inch Philips TV.

In my living room system I use Tannoy Westminster Royal Special Edition loudspeakers with Sablon Audio Panatela internal cabling, and the superb Duelund CAST external crossovers. Sablon AudioPanatela speaker cables connect to my restored vintage McIntosh MC225, MC30, and MC240 valve amplifiers, with Sablon Audio Panatela interconnects connecting the amps my restored vintage McIntosh MX110Z valve tuner-preamplifier, and a vinyl front end consisting of an Artisan Fidelity Statement Plinth in Macassar Ebony with Stillpoints Ultra isolation feet, a Classic Turntable Company modified Garrard 301 (Classic 301) with a brass platter, mounted with two of Thomas Schick's tonearms, one for mono with an Ortofon SPU Mono CG 25 Di MkII, and the other for stereo with an Ortofon SPU Classic GM MKII. Sablon Audio Gran Corona AC power cords connect my iMac & Mhdt Labs Havana USB DAC. A long pair of Acoustic Revive Single Core interconnects connects the Havana to my Mac preamp.

Listening Impressions
I listened to the SPEC RSP-901EX Real Sound Processor using my small room system, with the combination of my Harbeth Super HL5 loudspeakers and the SPEC RSA-M3 EX amplifier. I did not use the Real Sound Processors on the outboard Duelund crossovers on my Westminsters, as I would really need to use two pairs of Real Sound Processors, which I did not have access to.

Being unfamiliar technology, I wasn't really sure what to expect from the RSP-901EX Real Sound Processors, and I wondered if I'd even be able to hear a difference. In retrospect, I shouldn't have wondered, and I really liked what I heard them do with my Harbeths.

While I already mentioned the operational principles behind the SPEC RSP-901EX Real Sound Processors, let me summarise what Mr. Yazaki-san told me, and then briefly expand on the loudspeaker-amplifier frequency-impedance interaction that the RSP-901 EX is designed to improve. Basically, the RSP-901 EX is designed to provide an impedance correction for loudspeakers, whose impedance varies with frequency. There's a fairly complex relationship between an amplifier driving the speaker, and the speaker returning variable impedance based on frequency to the amplifier that it has to deal with while driving the loudspeaker. Minimising this interaction helps the amplifier perform better.

Right after listening to the SPEC RSP-901EX Real Sound Processors on my Harbeths, I had a conversation with my friend Siedy in the Netherlands, and the Dutch amplifier designer Jan Hut, who designed the 'Chaos' amplifier that Siedy uses to power his Westminster Royal loudspeakers, that has relevance for this topic.

Jan told me, "At the base of all amp designs stand engineers who learned to develop amplifiers the same way I did. That's because we all had teachers that think the same way on how you design amplifiers. Mostly they think that more is better, and a better measuring result will also be better to listen to music with. Even though measuring instruments do not know what better sound means, we think they do. The problem occurs in the feedback loop. An amp without feedback runs only one signal, the audio signal. It's not all that simple, but for now it will do. If you amplify that the right way it appears at the output, then goes to the speaker, and then back to the power supply. When you apply global feedback the amps sees more signals to work with. First the original input signal, and then the amplified signal that is sent back by the loudspeaker. The signal is passed along by the amp with a little delay and, and the amp has made little mistakes during the amplification process, which people try to compensate for by adding feedback, but then phase problems become an issue because the amp is comparing and compensating for these two signals. An average amp does not have any intelligence to do so, and it has no ears either, so new mistakes are made and enter the amp by the feedback and so on."

"The big bass signals are strong and stay rather unaffected, but the very small ones are affected, the ones that give us a part of the big spacious sound and three-dimensional picture. There is also another signal disturbing the audio signal when applying feedback, and that is the signal the speaker generates. The damping of the amp has to take care of that through the feedback loop also and so a third signal appears at the entrance of the amp and it tries to make the best of it. When you start adding even a small amount of feedback you can hear the spacious soundstage become smaller. So what we are asking is what's worse, letting the amp make a few mistakes we can't hear, or to introduce a lot of other signals by means of the feedback that the amp then has to deal with."

Jan's discussion was about the same phenomena that Mr. Yazaki-san told me about related to the complex interaction between the amplifier driving the loudspeaker, and the loudspeaker pushing back and 'driving the amplifier' which degrades the amplifier's performance by having to deal with multiple interacting signals. In Jan's case he told me about how he designs his amplifiers to minimize the deleterious effects of the loudspeaker-amplifier by using zero negative feedback designs, but Mr. Yazaki-san's idea is to introduce the SPEC RSP-901EX Real Sound Processor into the loudspeaker-amplifier relationship to help minimize the frequency-impedance variation interaction to improve the performance of any loudspeaker-amplifier combination. That's a cool idea.

Let me say that I listened to quite a lot of various types of music with the SPEC RSP-901EX Real Sound Processors installed on my Harbeth Super HL5 loudspeakers, and I found them to perform consistently & predictably across genres, but I'll limit myself to just a couple of examples to describe what I heard, then I'll move on and discuss the SPEC RSA-M3 EX Real Sound Amplifier.

On the Counting Crows' August and Everything After CD I swapped in and out the RSP-901EX Real Sound Processors while keeping the volume identical. The result was significant: the album's overall sound became warmer and richer, all of the images gained additional body & size and moved forward in the soundstage towards me, the sense of space in the soundstage became more expansive and 'darker'. On the emotive front, I thought the emotional connection was enhanced by the changes wrought by the RSP-901EX Real Sound Processors, the tone color became more intense, timbral textures became richer and more organic sounding, with the whole presentation of the music becoming less electronic sounding, and generally just more musically satisfying. Additionally, there was a more engaging 'feel' to the music, or maybe another way to say it was that the music felt more present in the room with me. The RSP-901EX Real Sound Processors worked as advertised, and I liked the improvement I heard from them when they were hooked up to my Harbeths.

On the Beautiful Dreamer Songs of Stephen Foster CD there's lots of great music by artists as diverse as Raul Malo, Allison Krauss, Yo Yo Ma, BR5-49, John Prine, Michelle Shocked, Mavis Staples, Roger McGuinn, and Ron Sexsmith, to name a few of the contributors. If there's ever an album that's begging to be released on 45RPM vinyl it's this one. Until then you can count on the RSP-901EX Real Sound Processors delivering the maximum emotional connection to the music from the CD, with rich tone, delicious timbral textures, a more natural presentation of vocal sibilants, an expansive sense of space, and an immersive 'in the room with you' presentation of the music.

Perhaps the most flattering thing I can say about the RSP-901EX Real Sound Processors' contribution to the performance of the Harbeth & SPEC RSA-M3 EX amplifier combination, is that when I had them hooked up to the Harbeths I tended to just get lost in the music more, and think less about the comparative listening process for the review. The RSP-901EX Real Sound Processors really let the emotional connection of the music shine through. The Harbeth Super HL5 loudspeakers & SPEC RSA-M3 EX Real Sound Amplifier combination sounds great, and it sounds even better when the RSP-901EX Real Sound Processors are hooked up to the Harbeths.

I replaced the SPEC RSA-M3 EX Real Sound Amplifier with my Leben CS-600 integrated amplifier, and did some more comparative listening with the SPEC RSP-901EX Real Sound Processors on & off the Harbeth Super HL5 loudspeakers.

Mr. Yazaki-san had mentioned to me that the magnitude of improvement the SPEC RSP-901EX Real Sound Processors provide was greater for solid-state amplifiers than it was for tube amplifiers, so I was expecting to hear a more modest improvement with my Leben CS-600 in the system. However, contrarily I found that the magnitude of improvement from the SPEC RSP-901EX Real Sound Processors was much greater with the Leben CS-600 than it was with the SPEC RSA-M3 EX Real Sound Amplifier. Perhaps the SPEC amplifier is already designed in such a way to minimize this loudspeaker-amplifier interaction?

The resulting changes from the SPEC RSP-901EX Real Sound Processors with the Leben CS-600 were of much the same nature (albeit greater in magnitude) as with the SPEC RSA-M3 EX Real Sound Amplifier: the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying.

I particularly recommend the RSP-901EX Real Sound Processors to my fellow Leben & Harbeth owners. If I may tickle your sense of intrigue a little, I think I can safely say that you haven't heard how good your Leben CS-600 integrated amplifier or Harbeth Super HL5 loudspeakers can sound until you've heard them with a pair of RSP-901EX Real Sound Processors helping them along. The SPEC RSP-901EX Real Sound Processors are one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

The Leben CS-600 & SPEC RSA-M3 EX Comparison

I think a lot of people will be interested in the comparison between the 'gold standard' Leben CS-600 vacuum tube integrated amplifier (my long time integrated amplifier reference) and the SPEC RSA-M3 EX class-D integrated amplifier. There is a bit of a price mismatch between the two, with the Leben CS-600 being around $6,500 USD, and the SPEC RSA-M3 EX being in the neighbourhood of $9,500 USD. However, the Leben has a reputation of being a giant killer, so lets check out how it fares against the exotic SPEC RSA-M3 EX Real Sound Amplifier.

The Leben CS-600 vacuum tube integrated amplifier really turned my head when I reviewed it back in 2007, and it has been a constant fixture in my small-room system since then. The Leben CS-600 also wowed a lot of people with its superb performance at the Salon & Image Show in Toronto in the years following that review, including the cast of excellent Stereophile writers like Stephen Mejias, John Atkinson, Robert Deutsch, John Marks, and Art Dudley, who heaped praise upon it.

If I were to blindfold you and play a little music for you on my Harbeth Super HL5 loudspeakers based system with both the Leben and SPEC integrated amplifiers, and then asked you which amplifier was the vacuum tubed amplifier, I bet 8 out of 10 of you would pick the SPEC RSA-M3 EX as the tube amplifier.

That's right, in an intriguing morphing of perceived reality the solid-state SPEC RSA-M3 EX sounds more like I think most people would imagine a vacuum tube amplifier to sound than the actual vacuum tube Leben CS-600 integrated amplifier does


The Leben CS-600 and the SPEC RSA-M3 EX amplifiers have considerably different voicing when it comes to their overall sonics & musicality, yet both of these integrated amplifiers are eminently musical devices that I think anyone would be overjoyed to own.

Using a broad brush, the SPEC RSA-M3 EX sounds tonally richer, warmer, darker, smoother, has a more relaxed & colorful presentation, and sounds more timbrally natural than the Leben CS-600.

The Leben CS-600 and SPEC RSA-M3 EX are both capable of throwing a wide & deep soundstage, and they both present a similar sized soundstage for a given recording, but what I heard within the soundstage was very different for these two amplifiers.

If the SPEC RSA-M3 EX Real Sound Amplifier's sound was a photograph, the slider for 'structure' would be set to the middle 'natural' position, with nothing added or taken away from the natural level of detail your eyes would perceive in the images contained within the photograph. The SPEC indeed does have 'real sound' just like the name says, but 'real' in the sense of how your ears hear 'real live music' in life, with natural levels of brightness, detail and micro-contrast, as opposed to the enhanced sense of 'structure' that the Leben CS-600 has.

The Leben CS-600 has the sonic 'structure' slider moved a little to the right of natural, being brighter, with more fine details that pop out, and with micro-contrasts that are more pronounced. The Leben's is not an unpleasant portrayal of the musical 'film' but it is more than you would usually hear at a concert in life, and not quite as natural sounding as the SPEC RSA-M3 EX's level of structural detail.

Staying with the Viveza analogy let me talk about the 'brightness' slider that controls the overall lighting level in a photograph. If you slide the brightness slider to the right the overall image gets brighter, and if you slide it to the left the overall image gets darker. In this context, the soundstage through the Leben CS-600 was brighter, like someone turned up the lights on the stage. The SPEC RSA-M3 EX was just the opposite, and it was like someone turned down the stage lights, giving a darker presentation of the same expansive soundstage. In aural terms this gave the Leben CS-600 a shimmering quality—a sort of 'glamor glow'—to the sense of space within the soundstage. Listeners who enjoy an enhanced sense of space from a recording will like that sonic feature of the Leben CS-600. I will point out that when you listen to live music that you don't really hear this enhanced 'sense of space' effect, it's something that comes from recorded music that doesn't exist to any extent in real life, rather it's a pleasant artifact from the recording process. Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

At the risk of wearing out my Viveza analogy, I will mention one final aspect related to 'contrast'. When you move the Viveza 'contrast' slider to the right you increase image contrast by making the darker tones deeper and lighter tones brighter. This makes darker colors look more deeply saturated and lighter colors look brighter, and the image looks a little darker but more colorful overall. If you move the contrast slider to the left the darker tones get lighter and the lighter tones get slightly darker, with the overall effect being that the image looks somewhat bleached out and less colorful overall. In this case the Leben CS-600's level of aural contrast is almost exactly in the middle, whereas the SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colors, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone color.

Now let me put all those comments about structure, brightness, and contrast into context as to how they affect overall resolution, transparency, soundstaging, sense of soundspace, and imaging.

The Leben CS-600 has more resolution compared to the SPEC RSA-M3 EX, and it gives a more detailed representation of a recording than does the SPEC. The SPEC RSA-M3 EX has less resolution than the Leben CS-600, yet it is more comparable to the amount of detail I actually hear when listening to live music, and in that sense it is more accurate and realistic.

Both the Leben and the SPEC have similar levels of aural transparency back into the depths and widths of their soundstages, and they both present similar recorded width & depth for a given recording. I found that a little bit counterintuitive given the more brightly lit presentation of the Leben, as I thought that would allow me to hear more deeply into the soundstage, but it did not. They have roughly equal transparency even though the Leben is brighter and the SPEC is darker overall.

As I mentioned earlier, the Leben CS-600 has an enhanced sense of soundspace compared to the SPEC, which gave the Leben CS-600 a shimmering quality—a sort of 'glamor glow'—to the sense of space within the soundstage. Listeners who enjoy an enhanced sense of space from a recording will like that sonic feature of the Leben CS-600. This is a sonic 'enhancement' on the Leben's part, albeit an enjoyable one, but the SPEC actually comes closer to sounding like a normal acoustic signature you hear when listening to live music in a natural acoustic setting.

The way images are presented on the soundstage for the Leben and SPEC differ quite a lot. The first difference is in image size, where the SPEC consistently delivered larger sounding images than the Leben. It's a little bit like the difference I see when I use a 35mm lens on my Leica M9 camera compared to a 50mm. The 35mm lens puts images further from me so they look smaller. The 50mm lens puts images closer to me so they look bigger, and for some reason the 50mm images look more like I see images with my unaided eyes. Likewise, the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The images on the soundstage with the Leben were more holographic, and the edge outlines of the images were more defined. The SPEC's images had more diffuse edge outlines, but were more solid in a natural flesh & blood sort of way, and the Leben's holographic images were a little more transparent and a little more 'ghost-like'. So on the imaging front I think the SPEC produces images that are more like I hear when I listen to live music, yet the Leben's presentation of images can be quite enchanting in an audiophile sonics sort of way.

Ok, up until now I've been mostly talking about how these two integrated amplifiers are voiced from an audiophile-style 'sonics' perspective, but lets take a closer listen to how they handle the actual fabric of the music, from a 'timbral realism' perspective in the context of textures, colors, and tones & overtones of the music; and also in the way they handle tempo, melody, harmony, rhythm, dynamics, and loudness.

If you've read between the lines in my descriptions above you've already guessed that the SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. The Leben resolves more information, and that can be interesting, but it gives more timbral information than you'd usually hear in a concert, so the timbral textures aren't quite as convincingly natural as the smoother & richer, more texturally accurate presentation of the SPEC. The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

When it comes to dynamics I think the Leben CS-600 is the more dynamic of the two, and that it infuses melodies with an extra little bit of pep as they move along. Tempo-wise, I think the Leben CS-600 sounds more energetic, and it highlights the differences in the speed of tempos to a greater extent, which makes it exciting to listen to, particularly on music with faster tempos. The SPEC is smoother and more relaxed sounding than the Leben, and while you can definitely tell the difference in tempos, the difference is not as pronounced as with the Leben. The increased resolution of the Leben makes harmonies more obvious, but not necessarily as realistic sounding as the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. The rich, smooth, colourful & darker balance of the SPEC really becomes an asset as the volume levels go up, and it makes listening at loud levels very gratifying.

Well that's enough of picking apart the performance of these two superb integrated amplifiers in my Harbeth Super HL5 based hi-fi system. While I feel obligated to delve into the details of their performance and to try to articulate it for you to give you a better idea of what makes them tick, it is in some ways a disservice to both of these integrated amplifiers, because a reductionist approach to aural analysis hints that the complexities of these amplifiers performance is nothing more than the sum of their sonic & musical parts, which is in fact rather grossly misleading.

There's a reason that the Leben CS-600 has won so many accolades from the audio press, and that it has remained my gold standard for an integrated amplifier for so many years, as it is a ridiculously good amplifier that is a blast to listen to music with. The strengths of the Leben CS-600's voicing is that it has an articulate, almost delicate, charming sonic palette, with a brightly lit enhanced sense of space, a sweet presentation of enhanced detail, a lively sense of tempo, and a bright, bubbly, upbeat presentation of melodies that makes music very compelling to listen to. You can also entertain yourself for a lifetime swapping in and out a broad variety of different vacuum tubes to tailor its overall sound to your tastes. If the Leben were a wine, it would be superb champagne, with bubbles tickling your tongue, and a clean, crisp, delicious flavor, whose presence makes every day life feel like a celebration. The Leben CS-600 on its own is a winner, plain and simple, and if you own one you should pat yourself on the back for making such a wise choice.

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone color. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. At $9500 USD for the SPEC RSA-M3 EX you would expect it to outperform the Leben CS-600 at $6500 USD, and it did. My Leben CS-600 isn't going anywhere though, I still love it, and I plan to continue using it as a reference for a good long time to come.

The Tannoy Westminster Royal Special Edition loudspeakers and the SPEC RSA-M3 EX

Now lets talk about the performance of the SPEC RSA-M3 EX Real Sound Amplifier driving my TannoyWestminster Royal Special Edition loudspeakers, which have been hot-rodded with the ultra-performance Duelund Coherent Audio CAST external crossovers, and wired internally with the superbSablon Audio Panatela cabling.

I've really been enjoying the combination of my restored vintage McIntosh MX110Z tuner/preamplifier and McIntosh MC225 stereo amplifier powering my West's, and the musical results I'm getting from that vintage Mac duo with the WRSEs has been the best I've ever heard, in spite of the vintage Mac pairing's relatively modest price.

Yves Beauvais restored and hand-voiced my little MC225 stereo amplifier. Among Yves' talents are the production of record albums, like the collected Ornette Coleman recordings on Atlantic, Beauty is a Rare Thing, Jorma Kaukonen's Blue Country Heart, and many more. So Yves really knows the whole recorded music process from recording to playback, and the way he voiced my little vintage McIntosh MC225 really highlighted his talents with its astonishingly natural musicality.

You can use the SPEC RSA-M3 EX as an integrated amplifier or as an amplifier only with the flip of a rear panel switch, so I flipped its switch and put it in its 'amplifier only' mode, and dropped it into the system in place of the beguiling little McIntosh MC225 stereo vacuum tube amplifier.

The SPEC RSA-M3 sounded natural and transparent, with lifelike tempos & melodies, and with a sense of space, holographic imaging, treble 'sparkle' and tactile presence of fingers on instruments, that came close to that of my hand-voiced MC225. The SPEC didn't have that extra little bit of 'glamour glow' effect that my vacuum tube MC225 did, but it sounded very, very, good.

A short listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

For the rest of the review I partnered the SPEC RSA-M3 EX with the New Valve Order SPA-II phono equalizer for vinyl duties with my Garrard Project 2015 player system (feature article to come), consisting of an Artisan Fidelity Statement Plinth in Macassar Ebony with Stillpoints Ultra isolation feet, a Classic Turntable Company modified Garrard 301 (Classic 301) with a brass platter, mounted with two of Thomas Schick's tonearms (one for mono with an Ortofon SPU Mono CG 25 Di Mk II, and the other for stereo with an Ortofon SPU Classic GM MKII). I connected the SPA-II to the SPEC with a pair of Acoustic Revive Single Core PC-TripleC RCA interconnects.

For digital duties I used my iMac with an Mhdt Labs Havana USB DAC, connected to the SPEC RSA-M3 EX with a very long pair of Acoustic Revive Single Core interconnects.

I absolutely adore listening to the superb Jazz24 stream, and I have it going almost all the time when I'm at home, while listening, lounging, or being a chef, and the fidelity is surprisingly good considering it's a stream. Jazz24 plays a broad selection of material too, from ancient crackly old jazz albums, all the way to jazz that is hot off the fretboard, and as such it gives me a lot of diverse material to quickly see how well a component performs across a wide range of music.

As an integrated amplifier the SPEC RSA-M3 EX really showed what it could do on the big Westminster Royal SEs. With the Jazz24 feed going directly into it, with no vintage McIntosh MX110Z tuner-preamplifier in the signal path before it, the sound was remarkably good, on par with—but not identical to—my vintage MC225 & MX110Z McIntosh combination, and from me that is high praise indeed.

The SPEC displayed superbly natural timbre & presence, with a smooth, rich, colorful, and musical presentation from material as diverse as 'Kathy's Waltz' from the Dave Brubeck Quartet's Time Outalbum, to '5-10-15 Hours' from Ruth Brown's Rockin' in Rhythm - The Best of Ruth Brown album.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce. In short, over the review period the SPEC impressed me with its sheer musicality and timbral realism that always made music enjoyable and edifying to listen to.

Ok, now that I have established that the SPEC makes digital media your friend, let's move on so I can tell you about what listening to vinyl records with the SPEC Real Sound Amplifier powering the big Westminster Royal SEs was like.

When I queued up the Analogue Productions 45RPM version of The Ray Brown Trio's Soular Energy on my Garrard Project 2015 player system I was immediately impressed by the sheer scale and presence of the music emanating from my Westminster Royal SE loudspeakers with the SPEC Real Sound Amplifier driving them. The images were totally life-size and had a 'they are here' reach-out-and-touch them presence in my living room that was really satisfying. On 'Easy Does It' the SPEC allowed Gene Harris' piano to positively sparkle with tone color and a compellingly vibrant melody line, with Ray's upright bass coming through with a lot of timbral realism, sounding just like an upright bass should in texture and tone, and Gerryck King's drum kit sounded realistic and tangibly present. On 'Mistreated But Undefeated Blues' the SPEC Real Sound Amplifier really gave the music swing & momentum, with a clear view into tempo and melody lines. Emily Remler's jazz guitar solo was superb, as was Red Holloway's sax solo, and they really had swing, momentum, and an engaging melody line. On Soular Energy the SPEC Real Sound Amplifier delivered music that was timbrally correct, full of color & life, and was intensely beautiful & emotional engaging.

The mono 45RPM Boxcar reissue of Julie London's Julie Is Her Name, Vol. 1, album, is beautifully done. The Boxcar reissue was mastered by Bernie Grundman from the original Liberty mono analog master on his all-tube disc cutting system, and pressed at RTI on two 180-gram records. I listened toJulie Is Her Name with the Ortofon SPU Mono CG 25 Di Mk II cartridge, which really brought out the considerable best in it (Thanks to Art Dudley for recommending this cartridge to me!).

On Julie Is Her Name, jazz guitar god Barney Kessel, and bassist Ray Leatherwood, accompanied Julie London to excellent effect. Through the SPEC Real Sound Amplifier Julie's vocal, Barney's guitar, and Ray's bass sounded astonishingly natural and 'real' on 'Cry Me A River'. The SPEC brought a high level of timbral realism and tone color to Barney's guitar and Ray's bass, and the sense of tempo and of the melody flowing along was just perfect. Natural, rich, beautiful presentation of tone color, musically engaging, and timbrally correct, describe the SPEC to a 'T'.

My buddy and vintage audio expert, Ron Barbee, stopped by for a visit while I was writing this up, and I put Julie Is Her Name on so he could hear the SPEC Real Sound Amplifier with the Garrard 2015 player system running the mono Ortofon. We ended up playing quite a few records, both mono & stereo, for some fun listening time. Ron's very familiar with my system, and I asked him what he thought of the SPEC in it. "It doesn't do anything wrong at all, and the SPEC's one of the best sounding amplifiers I've heard," said he. We talked about the SPEC and how its highs were spot-on perfect and natural sounding too, and Julie's vocals were stunningly natural, with absolutely no unnatural sibilance. The bass response was extended and full of nuance, and even though it was only 60 watts, the SPEC could really deliver the dynamic swings when called upon. The SPEC was deceptively powerful, and when loafing along it sounds only about as powerful as my 25 watt MC225, but when you really crank it up it never misses a beat and sounds astonishingly good, even at very loud 'blow out the windows' levels. In short, when we sitting there listening to the SPEC play music we came to the conclusion that it was one of the most perfectly voiced amplifiers we'd ever heard.

We also listened to the superb Cowboy Junkies' The Trinity Sessions. If you haven't yet experiencedThe Trinity Sessions I suggest you correct that oversight right now, as it's one great bit of music making, as well as being an audio benchmark of the sonic sorts. I love those good old mono records played back with good mono cartridges like the Ortofon, as they display amazing tone, timbre, and color, but listening to a record like The Trinity Sessions reminded me pretty quick that there are amazing aspects about great stereo records as well. The SPEC displayed the huge sense of space of the recording, filling my listening room with it, and the soundstage was at least triple the width of what you hear on even really good mono recordings. My take on things is that it's good to play back the mono vinyl you love with a dedicated mono setup to get the best out of that format, and to play back stereo masterpieces like The Trinity Sessions with a good stereo front end to get the best out of the stereo format, and to use a really great amplifier like the SPEC Real Sound Amplifier to get the best out of both of them.

One thing I really appreciated about the SPEC Real Sound Amplifier was that regardless of whether the source material was mono records, stereo records, or digital streaming, the SPEC drew the maximum amount of the music from them. A case in point is when musician, former model, and physicist friend Cindy dropped by, and I played her some of the same records I played for Ron. Cindy loves music, she's not an audiophile, but she readily hears what's going on with the music and the audiophile sonics. We started with a couple of nice mono records, Julie Is Her Name and Masterpieces by Ellington, and Cindy commented on the realistic and natural sound of the SPEC Real Sound Amplifier, and how good the recording of Duke's piano was on Masterpieces, and how good the SPEC was at delineating the tempo and time signatures. Cindy also noted that to get the most from a mono record you had to sit in the sweet spot evenly between the loudspeakers, but with stereo you had a much broader choice of seating position to get great sound.

Everyone who has heard the SPEC Real Sound Amplifier, including Cindy, has made the comment of how rich and natural the SPEC sounds (in a timbral and tone color sense), and Cindy added how it drew out many subtleties in the music, and had an ability "to remind you that recordings from your past are 'old friends'". I thought that the last was a particularly interesting comment, because the SPEC does indeed have an exceptional ability to portray music's emotional impact. It reminds you of how you felt when you heard the music for the first time, and it brings back all those feelings in a flood as you listen to the music. The SPEC infuses music with the same sort of intensity of emotions you experience when you sit down with an old friend to reminisce about past times, and the flood of emotions that comes with it.  

Summary & Conclusions

At the start of this article I mentioned that the SPEC RSA-M3 EX Real Sound Amplifier from the 'enlightened ear' of Mr. Shirokazu Yazaki in Tokyo, Japan, sounded shockingly good by every musical and sonic measure that I consider important when reviewing audio equipment.

Mr. Yazaki-san has artfully voiced the SPEC Real Sound Amplifier to be timbrally realistic, tonally colorful, evenly balanced from top-to-bottom, with sweet & natural high frequencies, a deliciously rich & liquid midrange, and a tight & tuneful bass. Tempos, time signatures, melodies, and harmonies were full of musical revelation in a very natural and 'live music' sort of way.

The SPEC Real Sound Amplifier has a way of making music your friend, whether it is mono or stereo vinyl, an FM broadcast, or a digital stream, and it has a rather unique ability to infuse listening to an old familiar music with the same sort of emotional intensity that reminiscing with an old friend evokes.

On my Westminster Royal SE loudspeakers, the SPEC Real Sound Amplifier provided some of the most musically satisfying and emotionally impactful musical performances I've ever heard coming from them.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

One thing I did learn about the SPEC during my time with it was to get the very considerable best out of it you need to get a good AC power cord on it. The stock AC cord is ok, and you can get by with it for a while, but if you want to hear what the SPEC Real Sound Amplifier is really capable of you need a good AC power cord, and the difference one makes is not subtle. I tried quite a number of power cords with the SPEC, and I found the two best with it were the Sablon Audio Gran Corona and Petit Corona (in that order).

The SPEC RSA-M3 EX Real Sound Amplifier is not cheap at an estimated US$9500 retail price, coming in a full US$3000 more than the superb vacuum tube Leben CS-600 integrated amplifier. As much as I love the Leben, I really think the SPEC is in a different performance category. A more appropriate comparator would be the hand-made, solid-state tour de force, ASR Emitter II Exclusive Version Blue amplifier from Herborn, Germany, that impressed me so much in Issue 66 when I reviewed it. It was simply awesome. Rather incredibly, the SPEC Real Sound Amplifier, while much less powerful at 60 watts, has all of the good performance attributes of Big Blue, but is even more timbrally realistic and tonally colorful, and the SPEC accomplishes that at slightly less than one-third of Big Blue's price of US$31,220 (excl tax). In that sense the SPEC RSA-M3 EX Real Sound Amplifier is a bargain.

I think that what we are witnessing here with the SPEC RSA-M3 EX Real Sound Amplifier may very well be the birth of something as musically significant as what happened with the advent of the DH-SET amplifier renaissance in 1960s Japan, but this time it is with a class-D amplification device from the 'enlightened ear' of Mr. Shirokazu Yazaki.

If you have been put off by the quirky nature and low power of DH-SETs, this could be your chance to check out that ol' SET magic with a thoroughly modern amplifier that is capable of driving a broad range of modern loudspeakers, and it could very well be your big 'aha' moment, just like it was for Jean Hiraga with DH-SETs way back when, and change the way you think about listening to recorded music.

The superb tone color and rich timbral textures that are normally the purview of fine vacuum tube designs are now present is this class-D amplifier from Mr. Shirokazu Yazaki. If you're interested in an amplifier with the beauty, tone color, timbral naturalness, and rich stereoscopic musicality of the best vacuum tube designs in a non-fussy and classy solid-state design, I suggest that you listen to the SPEC RSA-M3 EX amplifier. You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.

I found the SPEC RSP-901EX Real Sound Processors to be fascinating devices, and the premise that they can help minimise the frequency-impedance variation interaction of any loudspeaker-amplifier combination to improve their performance is a really cool idea. With my Harbeth Super HL5s and the Leben CS-600 / SPEC RSA-M3 EX Real Sound Amplifier the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying. The SPEC RSP-901EX Real Sound Processors are the real deal and worth their asking price, and one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

I would like to thank Mr. Shirokazu Yazaki for letting me interview him, listen to and write about his SPEC RSP-901EX Real Sound Processors and SPEC RSA-M3 EX Real Sound Amplifier, it was truly a privilege, and an enjoyable experience all the way around. I suspect we will be hearing much more about Mr. Shirokazu Yazaki and his designs for the SPEC Corporation in the near future.

 I would also like to thank the ever-gracious Mr. Yoshi Hontani for making arrangements for this review.

The Leben CS-600 & SPEC RSA-M3 EX Comparison

REVIEW SUMMARY: Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

The SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colours, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone colour.the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

The SPEC is smoother and more relaxed sounding than the Leben,..... the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. 

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone colour. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. 

A listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

EXTENDED REVIEW: As much as I love the Leben, I really think the SPEC is in a different performance category. 

I think a lot of people will be interested in the comparison between the 'gold standard' Leben CS-600 vacuum tube integrated amplifier (my long time integrated amplifier reference) and the SPEC RSA-M3 EX class-D integrated amplifier. There is a bit of a price mismatch between the two, with the Leben CS-600 being around $6,500 USD, and the SPEC RSA-M3 EX being in the neighbourhood of $9,500 USD. However, the Leben has a reputation of being a giant killer, so lets check out how it fares against the exotic SPEC RSA-M3 EX Real Sound Amplifier.

The Leben CS-600 vacuum tube integrated amplifier really turned my head when I reviewed it back in 2007, and it has been a constant fixture in my small-room system since then. The Leben CS-600 also wowed a lot of people with its superb performance at the Salon & Image Show in Toronto in the years following that review, including the cast of excellent Stereophile writers like Stephen Mejias, John Atkinson, Robert Deutsch, John Marks, and Art Dudley, who heaped praise upon it.

If I were to blindfold you and play a little music for you on my Harbeth Super HL5 loudspeakers based system with both the Leben and SPEC integrated amplifiers, and then asked you which amplifier was the vacuum tubed amplifier, I bet 8 out of 10 of you would pick the SPEC RSA-M3 EX as the tube amplifier.

That's right, in an intriguing morphing of perceived reality the solid-state SPEC RSA-M3 EX sounds more like I think most people would imagine a vacuum tube amplifier to sound than the actual vacuum tube Leben CS-600 integrated amplifier does.

The Leben CS-600 and the SPEC RSA-M3 EX amplifiers have considerably different voicing when it comes to their overall sonics & musicality, yet both of these integrated amplifiers are eminently musical devices that I think anyone would be overjoyed to own.

Painting with a broad brush, I would say the Leben CS-600 is brighter, more resolving & transparent, more open sounding, more dynamic, more forward sounding, and it subjectively sounds more powerful than the SPEC RSA-M3 EX (even though it is not more powerful at 32 watts compared to the SPEC's 60 watts).

Using that same broad brush, the SPEC RSA-M3 EX sounds tonally richer, warmer, darker, smoother, has a more relaxed & colorful presentation, and sounds more timbrally natural than the Leben CS-600.

The Leben CS-600 and SPEC RSA-M3 EX are both capable of throwing a wide & deep soundstage, and they both present a similar sized soundstage for a given recording, but what I heard within the soundstage was very different for these two amplifiers.

If the SPEC RSA-M3 EX Real Sound Amplifier's sound was a photograph, the slider for 'structure' would be set to the middle 'natural' position, with nothing added or taken away from the natural level of detail your eyes would perceive in the images contained within the photograph. The SPEC indeed does have 'real sound' just like the name says, but 'real' in the sense of how your ears hear 'real live music' in life, with natural levels of brightness, detail and micro-contrast, as opposed to the enhanced sense of 'structure' that the Leben CS-600 has.

The Leben CS-600 has the sonic 'structure' slider moved a little to the right of natural, being brighter, with more fine details that pop out, and with micro-contrasts that are more pronounced. The Leben's is not an unpleasant portrayal of the musical 'film' but it is more than you would usually hear at a concert in life, and not quite as natural sounding as the SPEC RSA-M3 EX's level of structural detail.

Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

At the risk of wearing out my Viveza analogy, I will mention one final aspect related to 'contrast'. When you move the Viveza 'contrast' slider to the right you increase image contrast by making the darker tones deeper and lighter tones brighter. This makes darker colours look more deeply saturated and lighter colours look brighter, and the image looks a little darker but more colourful overall. If you move the contrast slider to the left the darker tones get lighter and the lighter tones get slightly darker, with the overall effect being that the image looks somewhat bleached out and less colourful overall. In this case the Leben CS-600's level of aural contrast is almost exactly in the middle, whereas the SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colours, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone colour.

The way images are presented on the soundstage for the Leben and SPEC differ quite a lot. The first difference is in image size, where the SPEC consistently delivered larger sounding images than the Leben. It's a little bit like the difference I see when I use a 35mm lens on my Leica M9 camera compared to a 50mm. The 35mm lens puts images further from me so they look smaller. The 50mm lens puts images closer to me so they look bigger, and for some reason the 50mm images look more like I see images with my unaided eyes. Likewise, the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The SPEC's images had more diffuse edge outlines, but were more solid in a natural flesh & blood sort of way, and the Leben's holographic images were a little more transparent and a little more 'ghost-like'. So on the imaging front I think the SPEC produces images that are more like I hear when I listen to live music, yet the Leben's presentation of images can be quite enchanting in an audiophile sonics sort of way.

If you've read between the lines in my descriptions above you've already guessed that the SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. 

The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

The SPEC is smoother and more relaxed sounding than the Leben, and while you can definitely tell the difference in tempos, the difference is not as pronounced as with the Leben. The increased resolution of the Leben makes harmonies more obvious, but not necessarily as realistic sounding as the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. The rich, smooth, colourful & darker balance of the SPEC really becomes an asset as the volume levels go up, and it makes listening at loud levels very gratifying

The Leben CS-600 on its own is a excellent, plain and simple, and if you own one you should pat yourself on the back for making such a wise choice.

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone colour. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. 

A listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

As an integrated amplifier the SPEC RSA-M3 EX really showed what it could do on the big Westminster Royal SEs. With the Jazz24 feed going directly into it, with no vintage McIntosh MX110Z tuner-preamplifier in the signal path before it, the sound was remarkably good, on par with—but not identical to—my vintage MC225 & MX110Z McIntosh combination, and from me that is high praise indeed.

The SPEC displayed superbly natural timbre & presence, with a smooth, rich, colourful, and musical presentation from material as diverse as 'Kathy's Waltz' from the Dave Brubeck Quartet's Time Outalbum, to '5-10-15 Hours' from Ruth Brown's Rockin' in Rhythm - The Best of Ruth Brown album.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce. In short, over the review period the SPEC impressed me with its sheer musicality and timbral realism that always made music enjoyable and edifying to listen to.

I was immediately impressed by the sheer scale and presence of the music emanating from my Westminster Royal SE loudspeakers with the SPEC Real Sound Amplifier driving them. The images were totally life-size and had a 'they are here' reach-out-and-touch them presence in my living room that was really satisfying.

he SPEC Real Sound Amplifier has a way of making music your friend, whether it is mono or stereo vinyl, an FM broadcast, or a digital stream, and it has a rather unique ability to infuse listening to an old familiar music with the same sort of emotional intensity that reminiscing with an old friend evokes.

On my Westminster Royal SE loudspeakers, the SPEC Real Sound Amplifier provided some of the most musically satisfying and emotionally impactful musical performances I've ever heard coming from them.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

Listening Adventures with Tannoys with the Wonderful SPEC Amps - SPEC RSA-M3EX & SPEC RSA-F33EX
Siedy Abee

REVIEW SUMARY: Wow, Jeff was really impressed by this amp. It performed very impressively on his big Tannoy Westminster Royal SE loudspeakers. Based on his review I informed one of my best friends, Piet de Vries. I knew Piet was thinking about starting a company who is specialized in selling very nice audio equipment.  In line of what Mr. Yazaki-san (of the SPEC company) calls ‘Real Sound’. I told Piet about the SPEC amps. To put a long story in short words: Piet is now importing the SPEC amps! Wow! He started immediately with the whole range, including the RSA-F33EX!

EXTENDED REVIEW: I am one of those guys who is a regular reader of Jeff’s Place. It is always a great pleasure to open up Jeff’s website and to read about his newest adventures.

I had never heard about the SPEC RSA-M3EX before, and I started reading with interest about Jeff’s first listening experience with the SPEC RSA-M3EX. This is the middle model in the range of SPEC amps.

Wow, Jeff was really impressed by this amp. It performed very impressively on his big Tannoy Westminster Royal SE loudspeakers. Based on his review I informed one of my best friends, Piet de Vries. I knew Piet was thinking about starting a company who is specialized in selling very nice audio equipment.  In line of what Mr. Yazaki-san (of the SPEC company) calls ‘Real Sound’. I told Piet about the SPEC amps. To put a long story in short words: Piet is now importing the SPEC amps! Wow! He started immediately with the whole range, including the RSA-F33EX!

Yes, this was all inspired by Jeff!

Piet is also now the dealer for the Netherlands for Harbeth loudspeakers, Pennaudio loudspeakers and network-players from Lumin. Piet invited us to have a listen at his place. He lives very nice. He lives nearby the German border in a very rural area. Very quiet & lovely. The equipment we did the listening to and with:

Together with Jan Hut (the designer and maker of my Chaos mk2 integrated tube amp, cables, interlinks and who modified my beloved Philips CD 104 player) and Stefan we started listening to set 1.

Set 1.
Tannoy 15 DMT Mk2 speakers
Linn LP 12 – full Linn version
ASR Emitter 2 Exclusive version blue, with Accupower
SPEC RSA-F33EX
SPEC RSA-M3EX

We started with the mighty ASR Emitter 2 Exclusive amp. The sound was fine and we liked the way the Emitter was controlling the Tannoy 15 DMT. It was just the way an Emitter should sound, with a huge soundstage combined with lovely voices and an non-aggressive sound. As always it was as if we were listening to an nice tube amp with real-world power and slam.

After this Piet installed the SPEC RSA-F33EX. It is a bit strange to put an amp on the huge Emitter but there was no other place.  After a short time of warming up for the SPEC Piet hit the play button for the Lumin, and we were all quite shocked! This SPEC amp sounded very different compared to the Emitter. It sounded more spacious and holographic and at the same time very transparent & open, and it brought into the room a new sense of energy and musicality. How is this possible? We don’t know.

In a certain way I was sad about this. I do really love the sound and the looks of the Emitter, and now here was just a 1-box integrated amp (the Emitter has four boxes) that was outperforming the Emitter. After some discussion we concluded that the bass of the Emitter was perhaps somehow a bit more dominant, but only slightly. After listening to this awesome good sounding SPEC we turned it off and installed the SPEC RSA-M3EX.

After a nice cup of coffee and some delicious cake Piet turned up the volume and hit the play button. Immediately we could hear that this amp had the ‘SPEC family sound’. The same energetic, dynamic and tubelike sound as his bigger brother. The difference where not all that big! Be sure, when you have heard the F33EX you know that it is the way to go – end of story. But the F33EX is almost double the price of the M3EX. Is that worth the money? If you can live with 95% of the performance of his bigger brother than is the answer NO, if you want to have it than you have to buy the ‘bigga brotha’.

So, after these amazing listening experiences Piet brought us a nice beer. It tasted good!

Than we changed over to set 2.

Set 2.
Tannoy 215 DMT Mk2 speakers
Lumin D1 Network Player
SPEC RSA-M3EX

The sound was very nice and very like the sound of set 1. Although a bit less dynamic and holographic. Note: in later listening sessions we discovered that the 215 DMT Mk2 was not as precise as the 15 DMT Mk2. The soundstage was more diffuse compared to the 15 DMT, and not so pin-point in imaging. Overall we could hear also now the same fine musical sound as with set 1: very lifelike, organic, holographic and very musical! We really could hear what Yazaki-san means with “Real Sound’ reproduction.

After this Piet invited us to change our chairs again, so we could listen to set 3. 

Set 3.
Penaudio Sara SE speakers
Lumin D1 Network Player
SPEC RSA-717EX

A set with a lot of ‘Real Sound’ components! The cables were all from Western Electric. Piet did not warn us when he let the music play! WOW! What a nice sound! How was this possible! How could such a fine bass be produced by such a little speaker? It really sounded very musical and muscular! The sound was almost around us, as if were listening to 3D sound produced by a 2D set. The combination of this very nice speaker, little SPEC amp (the ‘717’), and the WE cables blew our minds! The big Tannoys produced a really big sound, and the sound of the Dual Concentric tulip wave unit was very precise and holographic, but listening to this more room friendly set-up was really nice.

This listening session was very involving, and we all want to thank Jeff that he inspired Piet to contact Yazaki-san of the SPEC Corporation! (You are welcome! Yazaki-san is a treasure! – Jeff)

In a later session Piet brought the SPEC RSA-F33EX with him to my house. Also on the Westminster Royal SE the sound was very involving. A very precise and controlled sound with spades of musicality and lifelike dynamics and again a very holographic sound. I could happily live with the SPEC amp! 

Testimonials

These Japanese SPEC engineers have certainly created a LOVELY, SMOOTH, TUBE SOUNDING, SOLID STATE INTEGRATED AMPLIFIER that is a PLEASURE to LISTEN to.
Hello Terry,
Thank you so much for the loan of your SPEC RSA-M3EX Integrated amplifier to listen and evaluate in my system over the weekend.

It just slotted into my system as though it had always been there and the remote control was such a pleasure to use. The blue light around the volume control knob was a very nice aesthetic touch.

I was most impressed with its sound especially when listening to CDs. It was warm, rich and lush yet detailed and I found it very ADDICTIVE to listen to for long hours into the night. 

I was also  delighted to find it had a Preamp-In function and I was able to enjoy records via my preamplifier/phono through it as well.

I would venture to say that it is one of the most MOST TUBE SOUNDING OF ANY SOLID STATE GEAR I have listened to in a long time, as you know listening to music though valve gear has been my choice for over 30yrs.

The sound stage did lack a bit in depth compared to my tube gear however it was very wide and I particularly enjoyed the sound of female singers with voice detail that was STUNNING AND OH SO CLEAR AND DETAILED .

The BASS weight was there in SPADES and the MID range was SUPERB.

I would have liked to hear a bit more air and treble and perhaps different interconnects or speaker cables would produce this result.

To Summerise:  

These Japanese SPEC engineers have certainly created a LOVELY, SMOOTH, TUBE SOUNDING, SOLID STATE INTEGRATED AMPLIFIER that is a PLEASURE to LISTEN to. 

It is a wonderful way to capture the music that is hidden in a CD collection and a real a REAL MUSICAL TREASURE.

……. Paul