Accustic Arts REFERENCE AMP-II Mk3 260w dual-mono Stereo power amplifier

AA 27 AS REFAMP
NZ$ 27,995.00 ea (incl. GST)
Accustic Arts

High-End from ACCUSTIC ARTS® is expected to sound natural and detailed,

New

ACCUSTIC ARTS® AMP II – MK 3: The 3rd generation - NEW for version MK 3: ACCUSTIC ARTS® damping factor linearisation

The long-term hit and classic in the ACCUSTIC ARTS® range is without doubt our solid AMP II power amplifier. In 1997, the year when ACCUSTIC ARTS was founded, the AMP II was one of our first products. Now, in the 3rd generation, we have hardly changed the look of the product at all. This is because in our opinion you shouldn't change a classic, but rather continue to further develop it to make the product even more attractive. As for some time now the AMP II has been recognised as one of the best power amplifiers available in the high-end scene, this has simultaneously become a challenge and an obligation. Therefore the question is asked: "What can one further improve with such a mature, good sounding product which has enjoyed success all around the world?"

Well, after numerous tests and trials we found out that a linearisation of the curve of the damping factor can actually lead to an improvement of the acoustic pattern. This does not merely entail fitting a few relays and resistors, etc., but also involves fine tuning the whole product and working out how to make the difference heard. After countless prototypes we came up with an interesting solution and integrated this solution in the new AMP II – MK 3. But as we have no wish to force it on anybody, the customer can also naturally switch off this function. Despite this, we speculate that most customers will love the new feature.

For more information on how the damping factor linearisation works, please have a look on the following link:  
http://www.accusticarts.de/pdf/produktblatt/details-daempfungsfaktor_en.pdf

AMP II: The world-wide award-winning champion

In recent years the model has been recognised with numerous awards in many international hi-fi magazines and many testers today refer to the device as a "reference".  The claim is therefore fully justified that the AMP II is one of the world's best output amplifiers in its class.

Here is an example from the press: In its issue 12/2009, the German magazine "STEREO" rated the AMP II – MK 2 (the MK 2 is the former version of the latest MK 3) as a reference output stage and awarded the product the maximum points. At the same time it described the value for money as "outstanding".
"STEREO" wrote:
"…
an output stage for high quality music, suitable for universal use and compatible to all loudspeakers. […] And clearly an inside tip for music lovers as this is the first time it has been possible to upgrade to the class of the top references for output stages for such a reasonable price."

Finest electronic components – finest sound

The top priority in the development of the AMP II – MK 3 was a perfect signal feed with short distances using the finest components. Some of the components are individually selected as this is the only way to realise the perfect measurement values which form the basis for the breathtakingly beautiful sound of this dynamic amplifier.

The AMP II – MK 3 is a so-called "dual-mono power amplifier", i.e. apart from the common mains cable both channels are completely separated from each other – from the transformer to the output stage board. This ensures the excellent values, for example, for channel separation and signal to noise ratio, etc. The high performance and simultaneously extremely low distortion in the AMP II – MK 2 is achieved using 2 x 1100 VA transformers, a filtering capacity of 160 000 µF, 24 selected MOSFET output transistors and much more. The result of this substantial oversizing is that even when working under high loads the components are never stretched to their limit of performance and therefore ensure the described excellent values. The AMP II – MK 3 works with Class A operation in most applications. And, despite its enormous power, the AMP II – MK 3 reproduces the finest details with extreme precision, in our opinion just as one would expect from a real reference product. 

Impressive circuitry concept – excellent measurement values

The driver stage of the AMP II – MK 3 works on the principle of the current mirror. This circuit principle enables power to be drawn from an existing current. The AMP II – MK 3 is therefore a "power-controlled" output amplifier whereby the large number of MOSFET transistors ensure a very high current capacity without having to stretch the transistors to their performance limit. The AMP II – MK 3 is therefore also suitable for impedance critical or low-ohm loudspeaker systems. Ingenious circuitry removes the need for a servo controller for the "offset" and the quiescent current is generated via the IC or current mirror driver.  As a result, direct and alternating current errors (DC and music signal errors) are immediately corrected. This means the total offset is exclusively determined by the quality and symmetry of the used ICs.

The comment from the "STEREO" laboratory in the issue mentioned above was as follows:
"High and stable performance level, extremely low distortion, high damping factor, good noise values and band width with extremely high channel separation".

Highest operational safety

Both output stage channels of the AMP II – MK 3 are equipped with a solid 12 kg heavy high performance heat sink which thanks to its special rib design serves to ensure a constant operating temperature of the MOSFET transistors. Even at full power there is no danger of overheating. An integrated control unit also permanently monitors operating conditions such as DC offset, temperature, clipping and high frequency. If a pre-defined value of one of these points is exceeded, the loudspeakers are immediately switched off to ensure the highest operational safety for the output amplifier and connected loudspeakers.

German engineering ingenuity

The AMP II – MK 3 is naturally "Handmade in Germany". All manufacturing processes for this product, from the development through to final assembly, are made in Germany.

To conclude, we would like to quote
"STEREO" once more:
Test result: "The amplifier is a model of stability and precision while at the same time versatile and agile, making the product a textbook example of how to build an amplifier. Homogeneous, universally usable, virtually perfect. And for this high-end product, an unbelievably reasonable price".

Features

Specifications

Reviews

Related

Videos

Features

Dual-mono reference power amplifier with completely isolated power supply for each amplifier channel
24 selected MOS-FET output transistors of finest quality
Magnetically shielded and encapsulated toroidal core transformer of premium quality for highest output reserves
Maximum total transformer power: 2,200 VA (watts)
Optimum smoothing thanks to 160,000 µF power supply capacity; Premium quality capacitors ("Made in Germany")
Very high damping factor for perfect speaker control
Professional protection circuit against clipping, HF oscillations and too high DC offset
Integrated switch-on current limitation for highest operational safety
Constant low operating temperature due to generously dimensioned heat sinks
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable
All used components and parts are selected and of highest quality
Very high quality, gold-plated bi-wiring/bi-amping speaker terminal
Extremely stable, massive and resonance optimised housing, fully made of aluminium; inlay made of massive brass, polished and chromed
ACCUSTIC ARTS® AMP II - MK2 is "Handmade in Germany"

Specifications

Voltage gain: 31.0 dB 
Total transformer power: 2 x 1.100 VA = 2,200 VA (watts) 
Power supply capacity: approx. 160,000 µF 
Input impedance: 
     balanced (XLR): 2 x 20 kΩ unbalanced 
     (RCA): 100 kΩ 
Rated power output: 
     max. 2 x 675 watts on 2 Ω (at THD+N = 0,1 %) 
     max. 2 x 450 watts on 4 Ω 
     max. 2 x 275 watts on 8 Ω 
Rise time/fall time: 3.1 µs with 4 Ω load (square-wave 20 kHz, 12 Vpp) 
Crosstalk: 109 dB with 1 kHz 
Signal-to-noise-ratio: -103 dBA (ref. 6.325 V) 
Intermodulation distortion: 0.007 % with 10 watts on 4 Ω 
Distortion factor (THD+N): 0.001 % on 4 Ω load at 1 kHz and 10 watts 
Dimensions (H x W x D): 350 x 482 x 430 mm 
Weight: approx. 55 kg 

Reviews

This is one of three solid state amps I have reviewed over the past 17 years that I would be happy having in residency in my system.
Gary Lea

REVIEW SUMMARY:
Both the Amp II and the PreAmp II reviewed separately are exemplary pieces, and I would recommend that anyone looking for the grunt of solid state with the warmth, ambience, and lack of edge of tubes, this is a great combo. As a standalone amp the Amp II represents the evolution of today's higher end solid-state pieces and their ability to deliver slam, detail, and sparkle with less of the edginess and in-your-face analytical sound that plagued solid state components for so long. This amp would do well in just about any system, but really comes into its own when mated to the PreAmp II, as they were absolutely made for each other. Check them out. You won't be sorry you did. +

EXTENDED REVIEW:
ACCUSTIC ARTS - Tube PreAmp ll Mk2 and Amp ll Mk2 combo review - Part Two – The REFERENCE AMP-II Mk2
 
This is a continuation of my review of these two Accustic Arts pieces. I pick up where I left off at the end of the PreAmp II Mk2 review. I left a bit of a crumb and a spoiler alert at the end of that review and it seems an appropriate opening for this part of the review.
 
The combination of the Accustic Arts PreAmp II Mk2 and the Amp II Mk2 is a union not to be taken lightly.
 
First the requisite propaganda, and as I always do I will provide you with the manufacturers comments directly.
 
"The basic circuitry and design concept of the current Amp II Mk2 is based on this original version. Naturally, over the years the Amp II Mk2 has been and continues to be refined and improved. But, as you would expect with a "classic", the typical cubic housing design remains unchanged. The top priority in the development of the Amp II Mk2 was a perfect signal feed, with short distances using the finest components. Some of the components are individually selected, as this is the only way to realise the perfect measurement values which form the basis for the breathtakingly beautiful sound of this dynamic amplifier. The Amp II Mk2 is a so-called "dual-mono power amplifier," i.e. apart from the common mains cable both channels are completely separated from each other—from the transformer to the output stage board. This ensures the excellent values, for example, for channel separation and signal to noise ratio, etc. The high performance and simultaneously extremely low distortion in the Amp II Mk2 is achieved using 2 x 1100 VA transformers, a filtering capacity of 160,000 µF, 24 selected MOSFET output transistors and much more. The result of this substantial over sizing is that even when working under high loads the components are never stretched to their limit of performance, and therefore ensure the described excellent values. The Amp II Mk2 works with Class A operation in most applications. And, despite its enormous power, the Amp II Mk2 reproduces the finest details with extreme precision, in our opinion just as one would expect from a real reference product."
 
The driver stage of the Amp II Mk2 works on the principle of the current mirror. This circuit principle enables power to be drawn from an existing current. The Amp II Mk2 is therefore a "power-controlled" output amplifier whereby the large number of MOSFET transistors ensures a very high current capacity without having to stretch the transistors to their performance limit. The Amp II Mk2 is therefore also suitable for impedance critical or low-ohm loudspeaker systems. Ingenious circuitry removes the need for a servo controller for the "offset" and the quiescent current is generated via the IC or current mirror driver. As a result, direct and alternating current errors (DC and music signal errors) are immediately corrected. This means the total offset is exclusively determined by the quality and symmetry of the used ICs.
 
The heavy parts:
Dual-mono reference power amplifier with completely isolated power supply for each amplifier channel
24 selected MOS-FET output transistors of finest quality
Magnetically shielded and encapsulated toroidal core transformer of premium quality for highest output reserves
Maximum total transformer power: 2,200 VA (watts)
Optimum smoothing thanks to 160,000 µF power supply capacity; Premium quality capacitors ("Made in Germany")
Very high damping factor for perfect speaker control
Professional protection circuit against clipping, HF oscillations and too high DC offset
Integrated switch-on current limitation for highest operational safety
Constant low operating temperature due to generously dimensioned heat sinks
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable
All used components and parts are selected and of highest quality
Very high quality, gold-plated bi-wiring/bi-amping speaker terminal
Extremely stable, massive and resonance optimised housing, fully made of aluminium; inlay made of massive brass, polished and chromed
 
So again here we are at the part of this session where we have to attempt to relate what all this means to the ears. What it means is a whole lot of nothing and yet a great deal of everything!
 
Once I mated the Amp II to the PreAmp II I wondered aloud to myself if this subsequently created a system 4? What with two pieces dubbed II together it seems logical that the grouping would result in an Accustic Arts Amp/PreAMP MK4 system (II plus II – get it?). I think I will offer this marketing genius to Accustic Arts for a small fee!
 
My comments from the Pre-Amp review in regards to the listening session are actually very similar, but tweaked to point out the individual contribution of the amp. I spent the first half of my review time having the pre-amp resident in my system with my Music Envoy amps. Then came time to take the Envoys out and replace them with the Amp II. The change to the system brought about some noticeable and quite satisfying changes to the overall presentation of the music. For continuity I stuck with the same playlist and in the pretty much the same order as I did with the pre-amp.
 
I started my sessions this time on the combined unit listening to my normal selection of songs.
 
As is generally the case I tend to start with a familiar old friend. In Eva Cassidy's, "Somewhere Over the Rainbow" from her Songbird album, what I immediately noticed about the delivery of the Amp ll was that there was a stark contrast between this amp and the Music Envoys, but not in the way I was expecting. What happened was that this amp had surprising warmth to it. While it did not have as much warmth as the Envoys, it did seem to remove a bit of a halo, or veil, off the music. It was slight, but enough to make me immediately notice it. As with the addition of the Pre-Amp II into the system there was a sudden change to the overall dynamic. It was suddenly less laid back and a bit more "in your face," but not the least bit offensive, just different and definitely more articulate in detail. The result right out of the start was a more dynamic presentation that had more defined edges to everything.
 
I then brought up a song that I recently stumbled upon while watching Jools Holland's show on TV. I was passively listening, got up to go to the other room for a second, and when I returned a singer was fronting a band, and I was drawn into the music. I had no idea as I sat there at first who the singer was. I was just drawn into the voice and the melody. Neither the song nor the singer blew me away, but I was enjoying it. I kept looking at the face of this rather slender gent, and suddenly it dawned on me that I was grooving to the soulful vibes of a rejuvenated, healthy, and vocally fit George Allen O'Dowd, more affectionately known as Boy George, whom I have always said I could not stand. I thought of him as a frivolous flash in the pan, more attention grabbing for the extreme gender bending than for any real vocal talent.
 
Lo and behold I had to do a bit of re-examination of his talent. The song, "King of Everything" off his new album This Is What I Do, showed a matured singer who has risen from the ashes with a more refined voice and a sensibility that totally eluded him in his younger days. He now appears to be more concerned with being a serious singer and artist than a freaky side show character. This particular song has a solid back beat, and a self descriptive story that is captivating. Through a system being fronted by the Accustic Arts PreAmp II MK2 you are right in front of the singer, and he drew you near enough to think he was simply telling you he was back with a vengeance. No, I do not plan on joining the Boy George fan club, but I did enjoy the song. There was the solid rhythm section fully backing the typical pop tune ensemble. The piano not only delivered the notes but also the percussive nature the instrument operates by. It was delivered in way that actually felt like I was sitting in the audience during the Holland show. Good bass delivered in a tuneful manner, but with impact and the kick drum driving the whole thing and pushing enough air to move the hair on your head. Right there up close with a small group of club goers who just stumbled on the resurfacing of a has-been reborn. His voice was articulate and very strong with smoothness and an almost pleasing quality to it that I do not remember him to have possessed in the past.
 
As we were heading into the holiday season I could not pass up a chance to add Emerson, Lake and Palmer's, "Father Christmas" from Come See the Show, The Best of ELP to my list. Easily the most cynical Christmas song ever written, and arguably one of the most beautiful! All of the sparkle of the acoustic twelve string guitar which supports the entire song, the string ensemble and full orchestra were there in full force with incredible detail, depth, and a width of the soundstage it would take to reproduce this piece live. At the point that the synthesised bass comes in it moves you a couple of inches in your chair. Shortly after that part of the song there is a harmonic chiming of the guitar, and the chime is brilliantly full with the requisite bloom and decay that you would have heard had you been listening to it live. Tympani drums filled the room along with all of the brass. I almost expected my ceiling to open and angels to descend from heaven. The presentation from the soft intro, through the build up and the climax of the end was absolutely glorious!
 
Where I ended my official last session was with a song, that for various reasons has become very near and dear to me and that is Warren Zevon's "Keep Me in Your Heart" from his final album The Wind.
 
Stark, direct, and self-confessing, this tune hits deep in the soul and requires a sound system that merely conveys the pain, the resolve, and the hope of one man that he will not be forgotten as the moments of his life are rapidly ticking down. When most are faced with imminent mortality it tends to draw the most naked, uncluttered, and raw emotions out of us all. It is in those moments that most pure feelings and thoughts come to the surface. (I know as I have been there more than once in my own life) This is not something you want a HiFi system to alter by injecting its own biases into the musical performance.
 
With "Keep Me in Your Heart" the presentation was, well to put it bluntly, honest! I am not sure there is much more to convey about the musical presentation that the Accustic Arts unit provided. In a way it sounds anticlimactic, but in reality it was an astonishing moment. Nothing false added. No strident highs with any biting edge, nor was there a fuzzy bloating masquerading as warmth. It was natural and much like I would have heard if a few of my musician friends and I had grabbed some guitars and sat around playing music together. It literally brought a dying man, who could easily be my friend, into my listening room where he shared with me through his music a concern we all have about being lost to time and other lives that continue after we leave this life. Intimate, raw, moving, sad, and yet somehow comforting to know I am not alone in that particular concern. All of the emotion just flowed out of the system into the room and enveloped me like a warm blanket.
 
This effect was even more pronounced with the insertion of the Amp II in the system. Soundstage breadth and depth were impressive, and every song seemed to have an innate intimacy that I was not expecting it to create. What is missing in this amp that I usually find in solid state amps is an overly analytical presentation to the music. I think of it as a sort of sterility that I have often found to be off-putting. As the years roll on it seems that this trait is less and less prevalent. Them Amp II has none of that in the musical presentation. It is more natural and less biting than I am used to. It seems that some manufacturers are mastering the black art of making solid state more ear-friendly. That is just my opinion, but I feel it is the case. This is one of three solid state amps I have reviewed over the past 17 years that I would be happy having in residency in my system.
 
Both the Amp II and the PreAmp II reviewed separately are exemplary pieces, and I would recommend that anyone looking for the grunt of solid state with the warmth, ambience, and lack of edge of tubes, this is a great combo. As a standalone amp the Amp II represents the evolution of today's higher end solid-state pieces and their ability to deliver slam, detail, and sparkle with less of the edginess and in-your-face analytical sound that plagued solid state components for so long. This amp would do well in just about any system, but really comes into its own when mated to the PreAmp II, as they were absolutely made for each other. Check them out. You won't be sorry you did. +
………Gary Lea
At the end of the day, the Accustic Arts Amp II competed in a price category that more than doubles its own - fact is that it’s only in comparison to substantially more expensive amplifiers that I was able to fault the Accustic Arts Amp II at all
Jeff Fritz
REVIEW SUMMARY:
SOUND: 
"The Amp II MkI came across as sounding honest. Its presentation was balanced -- no aspect of its sound stood out. In fact, you might initially have a hard time identifying a sonic fingerprint from which to identify it." "A sharply focused soundstage, a smooth-sounding midrange and upper frequencies, and a general lack of veiling across the musical spectrum" define the Amp II-MkI performance.
FEATURES:
"Massive" solid-state amp that delivers "240Wpc (MkII-260w/ch) into 8 ohms, 400Wpc (MkII-425w/ch) into 4, and a whopping 600Wpc (MkII-650w/ch) into 2 ohms." "The output stage consists of 24 MOSFET transistors, 12 per channel, while filter capacitance is specified as 160,000 microfarads."
VALUE:
There will be better amplifiers than the Accustic Arts Amp II-MkI, but you’ll have to spend considerably more money to get a small measure of 'better.'"
 
EXTENDED REVIEW:
Please note - this review is of the earlier REFERENCE AMP-II Mk1 model back in 2004 that has since been upgraded to the latest and more powerful (260w/ch) REFERENCE AMP-II Mk2 model:
 
Although you may not have heard of the Accustic Arts brand name, the company behind it looks to be poised to become a force in specialty audio. In fact, in some parts of the world, Accustic Arts already is a force, evidenced in part by the exposure at the European High End show each year. Here in North America, however, the brand has until just recently kept a low profile.
 
Accustic Arts audio components are manufactured by Schunk Audio Engineering GmbH & Co., in Lauffen, Germany. What initially impressed me about the company, which led to my interest in this review, is the manufacturing prowess the parent company seems to possess over a full product line that includes: three amplifiers; an integrated amp; a preamplifier; a CD player, transport and DAC; as well as a line of speakers, cables and furniture. Accompanying the diversity of manufacturing is, apparently, equally adept electrical-engineering talent. The company's facility is featured prominently on the Accustic Arts website, and it appears to be the model of clean, efficient manufacturing.
 
Does all of this equate to good-sounding gear? It’s not enough to make all of the components I listed above; each one must be designed for audiophile performance from the start. If my experience with the Amp II-AC High Performance amp is any indication, Accustic Arts products appear to have the right stuff.
 
"Big Beauty"
 
Accustic Arts calls the Amp II-MkI High Performance amplifier the "Big Beauty." Whether the term sums up exactly what the company meant or something was lost in the marketing department’s translation, I can’t say. Regardless, the amp itself is big and, in a German sort of way, attractive. (I can’t bring myself to use the term beautiful when describing an amplifier, no matter how hard I try.) The Amp II is 14"H x 19"W x 17"D, making it appear massive while viewing it straight-on due to the imposing height. The appearance of the outer casework demands attention. The silver version I received is hard to miss, although I imagine the black edition appears a little more conventional for those inclined to go that route.

The AMP-II is a "Massive" solid-state amp that delivers "240Wpc (MkII-260w/ch) into 8 ohms, 400Wpc (MkII-425w/ch) into 4, and a whopping 600Wpc (MkII-650w/ch) into 2 ohms." "The output stage consists of 24 MOSFET transistors, 12 per channel, while filter capacitance is specified as 160,000 microfarads." with  two magnetically shielded, potted 1100VA toroidals in a dual-mono configuration. Comprehensive protection circuitry guards against clipping, high-frequency oscillation, and excessive DC offset. 

 
Fit and finish are what you would expect of an amplifier that costs over ten Gs: excellent. The faceplate is nicely machined aluminium with beveled edges and a chrome insert displaying the Accustic Arts logo as well as the push-button standby switch. The rear panel is outfitted with two sets of high-quality WBT binding posts for bi-wiring, a main power switch, the aforementioned XLR inputs, and a fuse button that must be reset anytime the unit is unplugged (The latter must be held down for a full three seconds to power up the amp, a fact that I initially overlooked, and one which caused me much frustration). The only criticism I have of the build is the somewhat thin, and therefore a bit flimsy, top plate. I would think a little more structural integrity could be gained from a slightly thicker panel covering the innards.
 
Busy rotation
 
My system has taken on many permutations during the course of this review. The Accustic Arts Amp II-ACHP was used with three different preamps: the Audio Research MP1, the Orpheus Labs Two, and a Blue Circle BC3000 Mk II, all of which provide balanced outputs, thereby avoiding any potential sonic degradation from adapters. Sources were the Esoteric DV-50, also used balanced, and the Lexicon RT-10. Both are universal audio/video players and were used with a variety of CD, SACD, and DVD-Audio material. I used Nordost Red Dawn interconnects and Red Dawn II speaker cables. Power conditioning was provided by a pair of Shunyata Research Hydra Model-2s and a single Model-8. Wilson Audio X-2 Alexandrias anchored the speaker section.
 
The Amp II-MkI operated without a hiccup throughout the review period and was mechanically silent during operation. I could hear no transformer buzz coming from inside the amp with my ear placed just a few inches away from the vented top plate. Whether coincidence or not, I’ve found amplifiers that have potted transformers, which the Accustic Arts amplifier does, to be much less susceptible to hum and mechanical noise. I don’t know about you, but buzzing electronics drive me crazy. The Amp II-MkI was silent.
 
Sound
 
First impressions with a variety of music were positive. The sound of the Accustic Arts amp immediately characterised itself with a sharply focused soundstage, a smooth-sounding midrange and upper frequencies, and a general lack of veiling across the musical spectrum. The Amp II came across as sounding honest. Its presentation was balanced -- no aspect of its sound stood out. In fact, you might initially have a hard time identifying a sonic fingerprint from which to identify it. This is usually a good sign, and oftentimes is one indicator of long-term satisfaction. I could find no instance where the Amp II-ACHP spot-lit certain areas of the musical spectrum, nor did it add any haze or impurities to the sound of my most demanding recordings.
 
Eva Cassidy’s Live at Blues Alley [Blix Street 10046] has become a favorite recording of late, with its forthright and natural-sounding presentation. The intro to "Tall Trees in Georgia," where Cassidy is introducing the song to her audience, presents a good opportunity to hear her spoken words without any instrumental accompaniment (except for an occasional strum of the guitar). The ambient environment of Blues Alley is tactile, as is Cassidy's voice. The Amp II reproduced Cassidy right in front with no image wandering or veiling of her voice. It also let the crowd and background noise through clearly without burying any details. The Accustic Arts amp handled this, the simplest yet hardest of tests, the human voice, with apparent ease. The rest of the album also provides a good test, as a number of acoustic instruments accompany Cassidy. The Amp II was able to keep the many elements of the performance separate, with no congestion or blurring.
 
Lest you think 240Wpc is lightweight in a world where super-powerful solid-state amplifiers are more common every day, don’t give it a second thought. Just to see if I could make the Amp II lose its composure I tried a frantic blast from Guns N’ Roses Live: Era ’87-‘93 [Geffen 490514]. The available power from the Amp II proved to be more than sufficient for exuberant listening levels -- "Rocket Queen" for all the neighbours to hear. My ears definitely gave up before the Accustic Arts amp did. Would more power sound better, or different? I wouldn’t count on it. I’ve heard intoxicating dynamic ease from amplifiers like the big Krell FPB-700cx, but I also heard that with the Accustic Arts Amp II. And there’s no guarantee that a more powerful amp would get the small-scale stuff right, as the Amp II did. If you’re considering one of the monster amps partly because of a high power rating, don’t count out this amp. Unless you have hugely inefficient speakers, I can’t imagine the Amp II-ACHP not having enough juice. It also kept perfect composure when playing loud. Well, as composed as possible while playing G’N’R.
 
I’m grown quite fond of Laurie Anderson’s Strange Angels CD [Warner Brothers WB25900-2], particularly "The Dream Before." This track manages a delicate balance between instrument and voice. The Amp II-ACHP was able to reproduce the quiet, delicate moments without losing any detail to the noise floor or shrinking the soundstage to an unnaturally small size. Just as we want our large floorstanding speakers to sound small when the occasion arises, we also want our powerhouse amps to shrink to the task of the more subtle recordings. The Amp II strikes a fine balance between power and finesse, not sacrificing one for the other. Bass weight was solid, which was evident on the first 45 seconds of "Monkey’s Paw." The sound was well paced and composed, just as you’d want.
 
Enter Gryphon and Halcro
 
I’ve been fortunate to hear a fair sampling of some of the best solid-state and hybrid amplifiers available, all within the context of the same timeframe, same system and same room. The Accustic Arts Amp II had some tough acts to follow as it entered my listening room, and it held up pretty well considering the price of some of the competing behemoths. To be honest, it’s only in comparison to these world-beaters that the Amp II's limitations come to light.
 
Compared with the Gryphon Antileon Signature stereo amplifier (US$24,000), the Amp II scored points with a lower noise floor and a more sharply focused soundstage. .....
 
The Amp II did not sound more or less powerful than the Halcro dm68 monoblocks (US$38,000). The German amp was wholly competitive with the 225Wpc Aussies in almost every respect until I reached the upper frequencies, where a lack of any noise, and frequency extension for miles, put the Halcros in a league unto themselves. The dm68s also sounded slightly quicker than the Amp II, although only by the slightest of margins. The Accustic Arts amp, though, did hold together the soundstage as well as any amp I’ve heard. I know I keep coming back to the term focus, but that is one key to the Amp II sound. If your speakers don’t have quite the image specificity that you’d like, try the Amp II and see if doesn’t improve.
 
At the end of the day, the Accustic Arts Amp II-MkI competed in a price category that more than doubles its own. While it was clear to me that you can get better sound in some areas by spending more money, you’ll find some performance characteristics that are simply hard to beat with the Amp II. You may still choose amplification like that from Gryphon or Halcro after hearing this amp, but at least you’ll know what you’re laying out all that additional dough for.
 
The end
 
There are better amplifiers than the Accustic Arts Amp II, but you’ll have to spend considerably more money to get a small measure of "better." The frequency extremes can be improved upon by shelling out the big bucks, but each listener will have to decide whether those performance improvements are important. The fact is that it’s only in comparison to some substantially more expensive amplifiers that I was able to fault the Accustic Arts Amp II at all. There were no glaring errors, and plenty of things to praise.
 
The bottom line is that Accustic Arts and the Amp II-MkI are real players in an industry populated with fine-sounding amplifiers. The Amp II casts a sharply defined soundstage while producing a balanced, clear view into the music. It’s also a powerhouse of an amp. This "Big Beauty" may prove a popular alternative to the usual suspects if its list of strengths is attractive to your audiophile sensibilities. Keep an eye out for Accustic Arts products, and the Amp II, at a dealer near you.
……Jeff Fritz
The combination of the Accustic Arts PreAmp II Mk2 and the Amp II Mk2 is a union not to be taken lightly.
Gary Lea

SUMMAERY: Both the Amp II and the PreAmp II reviewed separately are exemplary pieces, and I would recommend that anyone looking for the grunt of solid state with the warmth, ambience, and lack of edge of tubes, this is a great combo. As a standalone amp the Amp II represents the evolution of today's higher end solid-state pieces and their ability to deliver slam, detail, and sparkle with less of the edginess and in-your-face analytical sound that plagued solid state components for so long. This amp would do well in just about any system, but really comes into its own when mated to the PreAmp II, as they were absolutely made for each other. Check them out. You won't be sorry you did. 

EXTENDED REVIEW: This is a continuation of my review of these two Accustic Arts pieces. I pick up where I left off at the end of the PreAmp II Mk2 review. I left a bit of a crumb and a spoiler alert at the end of that review and it seems an appropriate opening for this part of the review.

The combination of the Accustic Arts PreAmp II Mk2 and the Amp II Mk2 is a union not to be taken lightly. First the requisite propaganda, and as I always do I will provide you with the manufacturers comments directly.

"The basic circuitry and design concept of the current Amp II Mk2 is based on this original version. Naturally, over the years the Amp II Mk2 has been and continues to be refined and improved. But, as you would expect with a "classic", the typical cubic housing design remains unchanged. The top priority in the development of the Amp II Mk2 was a perfect signal feed, with short distances using the finest components. Some of the components are individually selected, as this is the only way to realize the perfect measurement values which form the basis for the breathtakingly beautiful sound of this dynamic amplifier. The Amp II Mk2 is a so-called "dual-mono power amplifier," i.e. apart from the common mains cable both channels are completely separated from each other—from the transformer to the output stage board. This ensures the excellent values, for example, for channel separation and signal to noise ratio, etc. The high performance and simultaneously extremely low distortion in the Amp II Mk2 is achieved using 2 x 1100 VA transformers, a filtering capacity of 160,000 µF, 24 selected MOSFET output transistors and much more. The result of this substantial over sizing is that even when working under high loads the components are never stretched to their limit of performance, and therefore ensure the described excellent values. The Amp II Mk2 works with Class A operation in most applications. And, despite its enormous power, the Amp II Mk2 reproduces the finest details with extreme precision, in our opinion just as one would expect from a real reference product."

The driver stage of the Amp II Mk2 works on the principle of the current mirror. This circuit principle enables power to be drawn from an existing current. The Amp II Mk2 is therefore a "power-controlled" output amplifier whereby the large number of MOSFET transistors ensures a very high current capacity without having to stretch the transistors to their performance limit. The Amp II Mk2 is therefore also suitable for impedance critical or low-ohm loudspeaker systems. Ingenious circuitry removes the need for a servo controller for the "offset" and the quiescent current is generated via the IC or current mirror driver. As a result, direct and alternating current errors (DC and music signal errors) are immediately corrected. This means the total offset is exclusively determined by the quality and symmetry of the used ICs.

The heavy parts:

Dual-mono reference power amplifier with completely isolated power supply for each amplifier channel
24 selected MOS-FET output transistors of finest quality
Magnetically shielded and encapsulated toroidal core transformer of premium quality for highest output reserves
Maximum total transformer power: 2,200 VA (watts)
Optimum smoothing thanks to 160,000 µF power supply capacity; Premium quality capacitors ("Made in Germany")
Very high damping factor for perfect speaker control
Professional protection circuit against clipping, HF oscillations and too high DC offset
Integrated switch-on current limitation for highest operational safety
Constant low operating temperature due to generously dimensioned heat sinks
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable
All used components and parts are selected and of highest quality
Very high quality, gold-plated bi-wiring/bi-amping speaker terminal
Extremely stable, massive and resonance optimized housing, fully made of aluminum; inlay made of massive brass, polished and chromed

So again here we are at the part of this session where we have to attempt to relate what all this means to the ears. What it means is a whole lot of nothing and yet a great deal of everything!

Once I mated the Amp II to the PreAmp II I wondered aloud to myself if this subsequently created a system 4? What with two pieces dubbed II together it seems logical that the grouping would result in an Accustic Arts Amp/PreAMP MK4 system (II plus II – get it?). I think I will offer this marketing genius to Accustic Arts for a small fee!

My comments from the Pre-Amp review in regards to the listening session are actually very similar, but tweaked to point out the individual contribution of the amp. I spent the first half of my review time having the pre-amp resident in my system with my Music Envoy amps. Then came time to take the Envoys out and replace them with the Amp II. The change to the system brought about some noticeable and quite satisfying changes to the overall presentation of the music. For continuity I stuck with the same playlist and in the pretty much the same order as I did with the pre-amp.

I started my sessions this time on the combined unit listening to my normal selection of songs.

As is generally the case I tend to start with a familiar old friend. In Eva Cassidy's, "Somewhere Over the Rainbow" from her Songbird album, what I immediately noticed about the delivery of the Amp ll was that there was a stark contrast between this amp and the Music Envoys, but not in the way I was expecting. What happened was that this amp had surprising warmth to it. While it did not have as much warmth as the Envoys, it did seem to remove a bit of a halo, or veil, off the music. It was slight, but enough to make me immediately notice it. As with the addition of the Pre-Amp II into the system there was a sudden change to the overall dynamic. It was suddenly less laid back and a bit more "in your face," but not the least bit offensive, just different and definitely more articulate in detail. The result right out of the start was a more dynamic presentation that had more defined edges to everything.

I then brought up a song that I recently stumbled upon while watching Jools Holland's show on TV. I was passively listening, got up to go to the other room for a second, and when I returned a singer was fronting a band, and I was drawn into the music. I had no idea as I sat there at first who the singer was. I was just drawn into the voice and the melody. Neither the song nor the singer blew me away, but I was enjoying it. I kept looking at the face of this rather slender gent, and suddenly it dawned on me that I was grooving to the soulful vibes of a rejuvenated, healthy, and vocally fit George Allen O'Dowd, more affectionately known as Boy George, whom I have always said I could not stand. I thought of him as a frivolous flash in the pan, more attention grabbing for the extreme gender bending than for any real vocal talent.

Lo and behold I had to do a bit of re-examination of his talent. The song, "King of Everything" off his new album This Is What I Do, showed a matured singer who has risen from the ashes with a more refined voice and a sensibility that totally eluded him in his younger days. He now appears to be more concerned with being a serious singer and artist than a freaky side show character. This particular song has a solid back beat, and a self descriptive story that is captivating. Through a system being fronted by the Accustic Arts PreAmp II MK2 you are right in front of the singer, and he drew you near enough to think he was simply telling you he was back with a vengeance. No, I do not plan on joining the Boy George fan club, but I did enjoy the song. There was the solid rhythm section fully backing the typical pop tune ensemble. The piano not only delivered the notes but also the percussive nature the instrument operates by. It was delivered in way that actually felt like I was sitting in the audience during the Holland show. Good bass delivered in a tuneful manner, but with impact and the kick drum driving the whole thing and pushing enough air to move the hair on your head. Right there up close with a small group of club goers who just stumbled on the resurfacing of a has-been reborn. His voice was articulate and very strong with smoothness and an almost pleasing quality to it that I do not remember him to have possessed in the past.

As we were heading into the holiday season I could not pass up a chance to add Emerson, Lake and Palmer's, "Father Christmas" from Come See the Show, The Best of ELP to my list. Easily the most cynical Christmas song ever written, and arguably one of the most beautiful! All of the sparkle of the acoustic twelve string guitar which supports the entire song, the string ensemble and full orchestra were there in full force with incredible detail, depth, and a width of the soundstage it would take to reproduce this piece live. At the point that the synthesized bass comes in it moves you a couple of inches in your chair. Shortly after that part of the song there is a harmonic chiming of the guitar, and the chime is brilliantly full with the requisite bloom and decay that you would have heard had you been listening to it live. Tympani drums filled the room along with all of the brass. I almost expected my ceiling to open and angels to descend from heaven. The presentation from the soft intro, through the build up and the climax of the end was absolutely glorious!

Where I ended my official last session was with a song, that for various reasons has become very near and dear to me and that is Warren Zevon's "Keep Me in Your Heart" from his final album The Wind.

Stark, direct, and self-confessing, this tune hits deep in the soul and requires a sound system that merely conveys the pain, the resolve, and the hope of one man that he will not be forgotten as the moments of his life are rapidly ticking down. When most are faced with imminent mortality it tends to draw the most naked, uncluttered, and raw emotions out of us all. It is in those moments that most pure feelings and thoughts come to the surface. (I know as I have been there more than once in my own life) This is not something you want a HiFi system to alter by injecting its own biases into the musical performance.

With "Keep Me in Your Heart" the presentation was, well to put it bluntly, honest! I am not sure there is much more to convey about the musical presentation that the Accustic Arts unit provided. In a way it sounds anticlimactic, but in reality it was an astonishing moment. Nothing false added. No strident highs with any biting edge, nor was there a fuzzy bloating masquerading as warmth. It was natural and much like I would have heard if a few of my musician friends and I had grabbed some guitars and sat around playing music together. It literally brought a dying man, who could easily be my friend, into my listening room where he shared with me through his music a concern we all have about being lost to time and other lives that continue after we leave this life. Intimate, raw, moving, sad, and yet somehow comforting to know I am not alone in that particular concern. All of the emotion just flowed out of the system into the room and enveloped me like a warm blanket.

This effect was even more pronounced with the insertion of the Amp II in the system. Soundstage breadth and depth were impressive, and every song seemed to have an innate intimacy that I was not expecting it to create. What is missing in this amp that I usually find in solid state amps is an overly analytical presentation to the music. I think of it as a sort of sterility that I have often found to be off-putting. As the years roll on it seems that this trait is less and less prevalent. Them Amp II has none of that in the musical presentation. It is more natural and less biting than I am used to. It seems that some manufacturers are mastering the black art of making solid state more ear-friendly. That is just my opinion, but I feel it is the case. This is one of three solid state amps I have reviewed over the past 17 years that I would be happy having in residency in my system.

Both the Amp II and the PreAmp II reviewed separately are exemplary pieces, and I would recommend that anyone looking for the grunt of solid state with the warmth, ambience, and lack of edge of tubes, this is a great combo. As a standalone amp the Amp II represents the evolution of today's higher end solid-state pieces and their ability to deliver slam, detail, and sparkle with less of the edginess and in-your-face analytical sound that plagued solid state components for so long. This amp would do well in just about any system, but really comes into its own when mated to the PreAmp II, as they were absolutely made for each other. Check them out. You won't be sorry you did.
..........Gary Lea

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