Accustic Arts REFERENCE MONO-II 300w Mono Block power amplifiers (pr)

AA 13 AM RMONO
NZ$ 37,995.00 pr (incl. GST)
Accustic Arts

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

New

STEREO JAPAN - BEST PRODUCTS of the YEAR AWARD
AEX JAPAN - AUDIO EXCELLENCE AWARD
HK/CHINA – HiFi REVIEW - PRODUCT OF THE YEAR AWARD

USA – TAS THE ABSOLUTE SOUND - EDITORS CHOICE AWARD
MONO & STEREO - UPER ECHELON CLASS AWARD 
TAS THE ABSOLUTE SOUND EDITORS CHOICE AWARD - 2018 

ACCUSTIC ARTS® MONO II output amplifier is a recent addition to the ACCUSTIC ARTS® family of amplifiers and is the first amplifier from our company designed as a mono amplifier. The MONO II is based on the legendary AMP II, which enjoys worldwide popularity. 

"I have concluded that the Accustic Arts Tube Preamp II Mk 2 and Mono II amplifiers definitely are on my list for one of my Brutus Awards at the end of the year. They therefore definitely rate a "Ye Olde Editor's ‘Very Highly Recommended!’”………David W. Robinson - Positive Feedback Mag.

REVIEW SUMMARY:
“The affinity with the AMP II – MK 2, the best value amplifier among our STEREO top references, from Lauffen is unmistakable. But with even stricter selection of parts and components, a little modified and more powerful power supply unit and the natural advantages of the mono concept the MONO II wins by a nose technically as well as sonically.”……..Matthias Böde of STEREO on the MONO II:

Client's comment: Thank you so much Terry for these little beauties. I can not believe just how great they are. The detail, tightness, and warmth is truly amazing. Coming from a electronics background I always thought amplification was just a matter of numbers...DB gain, Current, Impedance etc that’s why I have always had the best source I can afford,thinking the sound can be only as good as the DAC’s etc at the front end. But boy! Have I been proven wrong these Mono ll’s just confirm that amplifier design is more of an art (excuse pun) than simple maths. I ended up taking the rest of the week off work for a kaleidoscope of listening pleasure. Thanks again...I think I owe you a beer next time I’m up that way. ...James

The typical, cube-like timeless ACCUSTIC ARTS® design of the housing with its Bauhaus style is now continued with the MONO II. The slim design of the housing makes MONO II excellently suited to positioning near to loudspeakers.

The ACCUSTIC ARTS® DNA:
Thorough development and best components = wonderful sound experience.
As is usual at ACCUSTIC ARTS®, during the development of the MONO II a high priority was the perfect signal feed with short distances and the use of the finest components. The printed circuit boards are only populated with components with very narrow tolerances. Selected components relevant for the sound are even tested manually to achieve an even higher selection standard. This effort is necessary to realise the technically perfect measurement values which form the basis for the exceptional sound experience of this amplifier.

The MONO II is purely a mono output amplifier. 
This guarantees the best values, e.g. with channel separation and signal to noise ratio as each channel has its own housing. Particular care was taken with the materials used in the MONO II to enable high performance with extremely low distortion. For example, the 1200 VA strong toroidal transformer made in Germany is manufactured from a special core, is encapsulated and additionally protected with Mu metal shielding. Eight enormous power supply capacitors manufactured in Germany to our specifications with a respective individual capacity of 10.000 µF supply 12 carefully selected MOSFET output transistors with perfect direct current. This means at full load the used components are hardly pushed to their performance limits and therefore with understatement ensure a carefree, agile acoustic pattern. In most application cases the MONO II works in so-called CLASS A mode. The MONO II is able to effortlessly play back a deep, powerful bass sound and at the same time reproduce fine details and is therefore quite rightly a product of our reference series.

Solid and proven technology – built to last

As with all ACCUSTIC ARTS® amplifiers, the driver stage of the MONO II works on the proven principle of the current mirror. This circuit principle enables power to be drawn from an existing current. The MONO II 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 MONO II 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.

Each MONO II has a generously dimensioned cooling surface which ensures a constant operating temperature of the MOSFET transistors. Even at full load there is never the danger of overload as the integrated control unit continually monitors the operating states of DC offset, temperature, clipping and high frequency. If a pre-defined value of one of these parameters is exceeded, the loudspeaker outputs are immediately switched off. This ensures the highest operational reliability for the output amplifier and the connected loudspeakers at all times.

The generous dimensions of the components and the use of proven technology means the MONO II will give its owner many years of listening pleasure. If, however, a problem should ever arise, the ACCUSTIC ARTS® service with its reputation for quality will be happy to assist you.

Our promise: Handmade in Germany
"Handmade in Germany" is part of the ACCUSTIC ARTS company philosophy and so naturally the MONO II is also exclusively made in our manufacturing facility in Lauffen am Neckar, Germany. The development, component insertion of PCBs and final assembly takes place in Germany and all housing parts and many individual components are sourced from long-term suppliers based in the south of Germany. Our specially trained and experienced technicians build this high-end audiophile amplifier from a large number of individual components.

Features

Specifications

Reviews

Awards

Related

Features

MONO II highlights (per piece) 
Reference class mono power amplifier 
12 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: 1200 VA (watts) 
Optimum smoothing thanks to more than 80,000 µF power supply capacity; Premium quality capacitors (“Made in Germany”)
Very high damping factor for perfect speaker control 
Professional protective circuit against clipping, HF oscillations and too high DC offset 
Constant low operating temperature due to generously dimensioned heat sinks 
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable on the rear panel 
All used parts and components are selected and of highest quality 
Premium quality, gold-plated bi-wiring / bi-amping speaker terminals 
Mains power switch on the front panel 
Extremely stable and resonance optimised, massive aluminium housing; inlay made of massive, high gloss polished and chromed brass 
Available in finish Silver (standard) and Satin Black (extra cost)
ACCUSTIC ARTS® MONO II is “Handmade in Germany” 

Specifications

Voltage gain: 31.0 dB
Total transformer power: max. 1200 VA (watts)
Power supply capacity: more than 80,000 µF
Input impedance: 
balanced (XLR): 2 x 20 kΩ 
unbalanced (RCA): 100 kΩ 

Rated power output: 
max. 300 watts on 8 Ω
max. 500 watts on 4 Ω
max. 700 watts on 2 Ω 

Rise time/fall time: 3.0 µs with 4 Ω load (square-wave 20 kHz, 12 Vpp)
Crosstalk: 111 dB with 1 kHz 
Signal to noise ratio: -104 dBA (ref. 6.325 V)
Intermodulation distortion: 0.007 % with 10 watts on 4 Ω
Distortion factor (THD+N): 0.0012 % on 4 Ω load with 1 kHz and 10 watts
Weight: approx. 25 kg 

Reviews

"I have concluded that the Accustic Arts Tube Preamp II Mk 2 and Mono II amplifiers definitely are on my list for one of my Brutus Awards at the end of the year". They therefore definitely rate a "Ye Olde Editor's ‘Very Highly Recommended!’”
David W. Robinson

SUMMARY: I"f audio gear is going to cave, this recording could certainly take them to that point. Lots of places to go sonically wrong here. No sweat for this Accustic Arts kit, though. Excellent dynamics; brass rendered as brass, and not as glass and razor blades. All's well with this recording via the Tube Preamp II Mk 2 and Mono II amps.Audio systems of the first rank will get this recording right, and make you wish that we were still making orchestral recordings so superbly these days. (We could, but it's gotten too expensive for most labels to consider. Pity!) Once again, the Accustic Arts Tube Hybrid Preamp II and Mono II Amps passed the test with flying colours. The Hungarian Rhapsody No. 2 growled, and the presentation of strings was very satisfying. At no point did the response of the AA gear tap out, bottom out, or sound congested". 

"Reliable. Stable. Excellent. Impressive to hear; gorgeous to look at. Summing up: Accustic Arts is producing dream machines for music lovers…with a hearty dose of Audio seductiveness, for sure. If you're in the market for a truly fine set of high-end audio electronics in this price range, then do yourself a favour: check out Accustic Arts". 

"I have concluded that the Accustic Arts Tube Preamp II Mk 2 and Mono II amplifiers definitely are on my list for one of my Brutus Awards at the end of the year". They therefore definitely rate a "Ye Olde Editor's ‘Very Highly Recommended!’”

EXTENDED REVIEW: A bloody busy year so far, with much more to go. One of the projects that I took on very early in 2018...with some hesitation, I confess, due to the workload that was already building...was an offer to hear the Accustic Arts Tube Preamp II Mk2 and Mono II Monoblock Amplifiers. It was going to be tough to work them in, 1/16 since I had other obligations that had already been taken on. Furthermore, I'd be at AXPONA 2018 in Chicago in April, and the Munich Show in May. Not much time left to evaluate unfamiliar components. But, I decided to give it a go, provided that the US distributor, Randy Forman, was willing to be patient. He was willing, and so I took it on. 

The story follows... 

Product details 
According to Accustic Arts, these are the specs for the review samples that were evaluated here. 

Accustic Arts Tube Preamp II Mk2 Specifications 
Inputs: 3 x fully balanced high level inputs (XLR), 2 x unbalanced high level input (RCA), 1 x surround bypass (RCA) Outputs: 2 x fully balanced line-out (XLR), 2 x unbalanced line-out (RCA), 1 x unbalanced fixed out (RCA), 1 x headphone output (1/4″ stereo female jack) Maximum gain: 4-times / 12 dB (balanced to balanced), 8-times / 18 dB (unbalanced to balanced) Signal difference left/right: 0.2 dB (from 0 dB to –40 dB) Input resistance: balanced: 2 x 50 kΩ, unbalanced: 50 kΩ Output resistance: balanced: 2 x 34 Ω, unbalanced: 34 Ω, AC coupled with 2.2 µF Max. output voltage: balanced: 19.8 Veff on 10 kΩ, unbalanced: 9.9 Veff on 10 kΩ Signal-to-noise-ratio: -90 dB (A weighted) Intermodulation distortion: 0.006 % with 4.0 Veff on 10 kΩ Distortion (THD+N): 0.002 % with 4.0 Veff on 10 kΩ (22 Hz – 30 kHz) Tube type: Dual triode E83CC / 12 AX 7 – selected and matched Power consumption: approx. 20 watts (unit totally on), approx. 3.5 watts (tube section in "standby" mode) Dimensions (H x W x D): 100 x 482 x 375 mm / 3.9 x 19 x 14.8 inches Weight: 12 kg / 26.4 lbs. 

Accustic Arts Mono II Amp Specifications 
Voltage gain: 31.0 dB Total transformer power: max. 1200 VA (watts) Power supply capacity: more than 80,000 µF Input impedance: balanced (XLR): 2 x 20 kΩ, unbalanced (RCA): 100 kΩ Rated power output: max. 700 watts on 2 Ω, max. 500 watts on 4 Ω, max. 300 watts on 8 Ω Rise time/fall time: 3.0 µs with 4 Ω load (square-wave 20 kHz, 12 Vpp) Crosstalk: 111 dB with 1 kHz Signal to noise ratio: -104 dBA (ref. 6.325 V) Intermodulation distortion: 0.007 % with 10 watts on 4 Ω 2/16 Distortion factor (THD+N): 0.0012 % on 4 Ω load with 1 kHz and 10 watts Power consumption: approx. 100 watts (without load) Dimensions (H x W x D): 350 x 240 x 430 mm/13.8 x 9.4 x 16.9 inches Weight: approx. 25 kg / 55 lbs. (depends on country) 

Setup 
I'm glad to say that setup of the AA gear was very straightforward. The amplifiers were only moderately heavy at about 55 lbs. (Believe me, we haul about amplifiers that are much heavier than this!) With the help of son John the Strong, I was able to shift the PASS Labs Xs 150 monos temporarily out of the way from the top shelf of the Critical Mass Systems rack. Then we hoisted the AA Mono II's into place. 

Likewise, the AA Tube Preamp II Mk2 preamp went onto the top shelf of our left Stillpoints ESS Grid Rack (#1), where it fit easily on our trusty-rusty Black Diamond Racing carbon fiber shelf. The preamp was hooked up to the amps via a longish run of Kubala-Sosna Elation! RCA cable…about 16 feet. The signal feed from the Merlot DSD DAC was via JENA Labs, with the JENA Labs Model Three providing power. These are known worldclass references in our system here, and would reveal any weaknesses in the Accustic Arts gear.

At the particular point that we were able to put the AA pre and amps into place, due to the complex cabling on the source side, we were without a turntable in range on that side of the listening room. (The Xact Audio The Beat Turntable with the Schroder Linear Tracking Tonearm did not have sufficient phono cable length to reach the AA preamp.) So that meant that we stayed with SACDs and Single, Double, and Quad DSD, via the splendid Playback Designs Sonoma stack (Merlot DAC, Syrah Music Server, and OPPO BDP-103 with OpBox optical converter). Given the terabytes of DSD recordings that we have in our reference library on our local area network here, and the relatively short time that I would be allocating for this review, this was no problem at all.

We hooked the RCA output of the Merlot Quad DSD DAC into one of the RCA inputs in the Tube Preamp II Mk2. Both the Playback Designs BDP-103 OpBox (SACDs) and the Syrah Music Server were connected to the Merlot, so it was the central connection point for passing signal on to the Accustic Arts electronics. 

Given the short review time line that was available, I fired the system up immediately. As usual, I powered up the AA Tube Hybrid Preamp first. It takes a minute or two to come up to speed, due to the soft-start circuitry that it (wisely) employs. Then I brought up the Mono II amps, a simply push-button operation. There were no problems upon initialisation, nor were there any during the weeks of review. The Accustic Arts gear was well-behaved, stable, and without any problems, anomalies, or complications. And no, you can't always count on that from high-end audio gear…just ask the guy who's had to deal with DOA components or troublesome power-ups more than once or thrice in his career. 

So…good show! 

A couple of quick notes on the AA components. 

First, they are drop-dead beautiful! ‘Nuff said! 

Second, the preamp is a hybrid, with tubes on the input side, and solid-state on the output. Its design is fully balanced, running in Class A. As Accustic Arts puts it on their Web site: 

"Tubes are excellent voltage amplifiers, but can only supply a limited amount of current. As a result, in the TUBE PREAMP II – MK2 we place the tubes exactly there where these clear advantages can influence the acoustic pattern, i.e. for the voltage amplification. In places where current has to be supplied, e.g. for impedance conversion, we use the proven premium IC OPA627® from Burr Brown / Texas Instruments. This combination allows us to achieve very low-resistance outputs which are also characterised by a high current capability. We use solid state technology and tubes to take advantage of their physical characteristics to realise an exceptional, analogue sound experience with an extremely low harmonic distortion and excellent harmonic distortion spectrum which sets standards. 
As opposed to most tube preamplifiers, the TUBE PREAMP II – MK2 is in factfully balanced, i.e. with 4 completely separate amplification stages from the signal input to the signal output. 

The 4 amplification stages are divided into one inverting and one non-inverting signal path per channel. Each of these amplification stages contains a high precision tube manufactured according to military specifications. This principle enables perfect channel separation. 

The loudness is adjusted via a high-end selective, high precision 4 channel potentiometer. It is natural that the TUBE PREAMP II – MK2 functions completely according to the proven Class A principle." 

The tubes used are the "so-called dual triode tube type E83CC" from the "tube group 12AX7." AA claims that this produces a result that is "…pleasantly warm with a very balanced sound pattern, a sophisticated bass range, clear high frequencies, good dynamics and low harmonic distortion." 

That's an encouraging sonic profile; the question was, would I hear these qualities in the audio trenches? 

Third, in terms of their design, the Mono II amplifiers were a different kettle of fish. They are beautiful monoblocks, of a relatively compact design, operating in pure Class A. There are no tubes here; 12 MOSFETs do the heavy lifting. The toroidal transformer is 1200 VA; according to Accustic Arts, there are "eight enormous power supply capacitors manufactured in Germany to our specifications with a respective individual capacity of 10.000 µF" to provide the power reserves. 

The power rating is 300 watts into 8 ohms, not quite doubling to 500 watts into 4 ohms, and topping out at 700 watts at 2 ohms. These are figures that will drive most speaker loads with reasonable authority and aplomb, and so should meet the needs of even the most demanding audiophile low-impedance loudspeakers (you know who you are!). 

I could fit the AA components in for evaluation for only about a month…it was time to jump to it. 

Listening impressions 

Since I had no turntable in operation, I focused on DSD- and SACD-based recordings. The albums that I used during my time with the Accustic Arts Tube Hybrid II preamp and Mono II amps were my usual gang of DSD references. Many of the DSDs were downloaded from key sites like NativeDSD.com, High Definition Tape Transfers (HDTT), Blue Coast Records, Acoustic Sounds' Superhirez.com, and Opus3 Records. Others were transferred from RTR tape and SACD. There were even some needle drops at Double DSD along the way. 

With all of these, the Playback Designs Sonoma System (Merlot Quad DSD DAC, Syrah Quad DSD Music Server, and Opbox-equipped OPPO BDP-103) supplied the serving, playing, and processing for the DSD sources that I used in this project. 

There are way too many of these to mention them all, even in a relatively short evaluation window. A few key recordings among them: 

Dead Can Dance, Into the Labyrinth, MoFi Japanese production on both SACD and pulled to Single DSD. (We have the complete DCD box set of SACDs, which is really quite excellent.) 

This recording, which we also have on MoFi Silver Label LP, has been a regular reference for component and system evaluation for years now. It provides DCD at their hypnotic best, with excellent spaciousness, great depth, beautiful harmonics, powerful dynamics, and deep bass. 

The Accustic Arts gear handled this recording easily, powering our Evolution Acoustics MM2/EXACT combination without skipping a beat. I was pleased with the performance, which had nothing to be ashamed of. 

Rubinstein, Chopin: The Nocturnes, Vols. 1 and 2, Sony Music SACD (stereo only), sourced from Amazon. 

Well, I'll confess it: I'm an absolute lover of Chopin, with the Nocturnes being special favorites of mine. Given the weather in Portland, there are tons of overcast, melancholy weather, with lots of opportunity for introspection and meditation. Many people suffer it; I welcome it, and cue up a range of recordings that harmonize with this soul mood. These two SACDs are from Sony's "RCA Red Seal Best 100" series. Rubinstein masters Chopin, and connects with his impassioned performances. This pair of SACDs is very highly recommended by me; if you love Chopin and have an SACD player, then you need these. 

The dynamics of great piano recording like these will test any system downstream. Quiet passages abound, with great delicacy of expression. I noticed that the Accustic Arts electronics was able to present shades, variations, and intonations with convincing clarity, not compromising the music in any way. Quite a fine result with this SACD. 

Ilya Itin, Debussy, Preludes Books I and II, Wave Kinetics Records, Quad DSD download (available at NativeDSD.com and Superhirez). 

An acid test! If you want to see how your system really handles a recording of performing brilliance and extraordinary dynamics, then Ilya Itin, a Steinway Contract Artist, recorded directly to Quad DSD by the team of Thom Moore and Robert Friedrich will certainly do it! The quiet passages are amazing, but the occasional thunderous moments will knock you back in your seat! This is one of the most fantastic piano recordings that I know of, combining Debussy (another favorite of mine) with an artist whose interpretation of the Preludes has become my current ne plus ultra. If you don't have this recording in its native Quad DSD, then you are missing out quite seriously, amigo! 

Can't handle Quad DSD? Then get yourself a Quad DSD DAC! (MSB DACs!) 

The Accustic Arts electronics took the extraordinary dynamics of this recording and rendered it quite well. I'm not too surprised at this result, given the prior performance and the specifications of the Mono II's, but since this recording does present a real challenge, I was glad to hear the AA gear acquit itself in a commendable way. With lesser gear, Itin's Preludes will out all weaknesses… 

Noriko Ogawa, Erik Satie on an 1890 Erard piano, Vols. 1 and 2. BIS SACD, stereo and 5.1 multi-channel surround. Sourced from Amazon. 

More of my spring-time melancholia music: Satie's solo piano music, performed by Ogawa on a vintage instrument. Her feel for Satie is superior, and her performances are recorded quite well by the folks at BIS. This is one of those contemplative SACDs that I cue up when the sky is gray, or the night has fallen, and I am tunnelling soulwards. Calm, expressive, moody, and powerfully humane, Satie, like Chopin, Debussy, Ravel, and Rachmaninoff, have direct access to my heart, and will always move me. Ogawa has a fine affinity for Satie, and hits the emotional connection to the music with directness and surety. 

Again, the Accustic Arts electronics pleased with their ability to handle the rich harmonics, and the emergence of contemplative, inward compositions from the silence convincingly. Notes emerging from a silky sonic blackness…very fine, indeed. 

Fiona Joy, Story of Ghosts, Blue Coast Records, Quad DSD download (also available in SACD). 

More wonderful, contemplative piano music, this time from a very gifted contemporary composer/performer. Fiona Joy is one of Cookie Marenco's artists, and records in Quad DSD for Blue Coast Records. Cookie's production chops match the wonderful artistry of Fiona Joy, whose work on this album takes me in the same emotional direction as her earlier fine recording, Into the Mist: Back to the best days and heights of Windham Hill Records. No surprise, really, since Cookie spent some time there back in the day. 

Fiona's album is a floating reverie, a relaxing, dreamy world in which I drifted, wrapped in her lovely musical visions. There are excellent dynamics of a pianistic sort, although predictably without pyromaniacal fortissimos. This is another inward journey, and not a firefight. 

The AA gear acquitted itself as outlined above; never an uncertain moment. 

Cootie Williams, Cootie Williams in Stereo, High Definition Tape Transfer in Quad DSD. 

Shift gears!
 
Here we have big-band brassy dynamics in a brilliant recording from 1958. Transferred wonderfully by Bob Witrak at HDTT, in glorious Quad DSD no less! (Great work, Bob!) A recording like this makes you wonder why so many of our contemporary albums pale in comparison. (Then you remember a trillion installations of Pro-Tools in garages all over the place, and you quit wondering.) 

I have been using this for a few years as another acid test of system performance, once that doesn't sacrifice musical values to achieve that end. Cootie and company bring back a feeling for the 1940's big-band days, with powerful swing and brass-that-sets-you-on-your-ass! We've used this recording in the past few years in our Positive Feedback Hospitality Room at the LA audio shows, to fantastic effect. Visitors are always wowed by the immediacy and dynamic punch of the recording, rendered smashingly in Quad DSD. 

If audio gear is going to cave, this recording could certainly take them to that point. Lots of places to go sonically wrong here. o sweat for this Accustic Arts kit, though. Excellent dynamics; brass rendered as brass, and not as glass and razor blades. All's well with this recording via the Tube Preamp II Mk 2 and Mono II amps.

Stokowski/RCA Victor Symphony, Rhapsodies, Analogue Productions SACD, stereo and three-channel multichannel (also available in stereo LP). 

Another automatic-reach-for-it reference recording. Stokowski's recording with RCA for their Living Stereo series, made in 1961, remains regnant in my audio library as one of the great orchestral recordings ever created. Deep growly bass, glowing strings, a mid-hallish soundfield, a nicely integrated harmonic structure, and rousing performances of the featured compositions, make for a memorable experience in one's listening room. Stokowski gets the most out of this orchestra, and the RCA team produced a brilliant testament to the possibilities of the audio arts in this album. The first track alone justifies the purchase of the SACD. If you don't have this recording in your library (SACD/LP), then you simply must add it. 

Audio systems of the first rank will get this recording right, and make you wish that we were still making orchestral recordings so superbly these days. (We could, but it's gotten too expensive for most labels to consider. Pity!) Once again, the Accustic Arts Tube Hybrid Preamp II and Mono II Amps passed the test with flying colours. The Hungarian Rhapsody No. 2 growled, and the presentation of strings was very satisfying. At no point did the response of the AA gear tap out, bottom out, or sound congested. 

Commendable.

Want more recordings?! 
In a word: smashing! Want a truly full-range pop recording of Ronstadt at her best, with full instrumentals? This is it. Available on QRP 200 gram LP, as well. Another reference album for me. 

Well, improbable as it sounds, this Waylon Jennings album, recorded in the early ‘60s, is really killer. Play it…dig it. By the way, I should mention that all of the Stockfisch SACDs that I have are simply outstanding…sonic masterpieces all. This "Analog Pearls" series has been very fine so far, although there are only two SACDs out at this point. Check Acoustic Sounds for details. 

Well…of course! Is any further comment necessary? (If you don't know what I mean, then pick up this recording on either SACD or 200 gram LP. You can thank me later.) 

Other recordings like those immediately above were run through the AA gear during the all too brief time that the Accustic Arts Tube II and Mono II could be placed and evaluated in our listening room. I particularly concentrated on Quad DSD, since in my view they represent the highest resolution currently available, but there were a number of SACDs, as well. Given the superior nature of SACD/DSD recordings via the Playback Designs Sonoma stack, certainly recordings were being reproduced at a stellar level…just what the doctor ordered! Over weeks, classical, jazz, rock, pop were all listened to…at no point did the Accustic Arts seize up, congest, tap out, harden, or overload. No faults; no failures; to problems to shake out. 

What's not to like?! 

Nothing, as it turned out....

Conclusion

If all of this sounds very favourable, and that I am very impressed with the Accustic Arts Tube Preamp II Mk2 and the Mono II amps, then you win the prize. I wasn't sure what to expect when they arrived, which is contrary to my usual practice these days of qualifying review projects ahead of time by hearing them at audio shows or the occasional distributor's demo. 

I took this one on spec, and will say that I'm glad that I did. In the short evaluation time window that I had for them, they won my heart with performance that was always musical, continually satisfying, and never failing in any audio virtue. While not the least expensive audio components on the market, with a fair amount of competition at its price points, Accustic Arts acquitted itself in a fine fashion, and left me quite impressed. 

Reliable. Stable. Excellent. Impressive to hear; gorgeous to look at. Summing up: Accustic Arts is producing dream machines for music lovers…with a hearty dose of Audio seductiveness, for sure. If you're in the market for a truly fine set of high-end audio electronics in this price range, then do yourself a favour: check out Accustic Arts. 

I have concluded that the Accustic Arts Tube Preamp II Mk 2 and Mono II amplifiers definitely are on my list for one of my Brutus Awards at the end of the year. They therefore definitely rate a "Ye Olde Editor's ‘Very Highly Recommended!’”
…… David W. Robinson

unquestionably gifted with macro-dynamics, these aren’t muscle-bound brutes. Nearly as an aside, they unravel the most gossamer tendrils and illuminate the quietest of details.
Frank Hakopians

REVIEW SUMMARY: with these monaural amps, temptation really can get the better of you, particularly so since all of the above didn’t just apply to the Acapella La Campanella but also Clockwork’s 2-way Event Horizon monitors. Stable into 2 ohms with sufficient reserves to set fire under the arses of sensitivity midgets, the Accustic Arts Mono II are archetypal classic muscle amps - but thankfully without the often attendant physical excess. No less compelling is their other side of finessed aesthetes with plenty of feel for musical structures, flow and the ability to not merely amplify but deliver an emotionally persuasive replay of the musical action to your speaker terminals. It’s a fact then than despite their not insignificant sticker, the Mono II do reset the yard stick plenty high. Definitely the devil in a red dress wearing Prada. Whosoever falls for it ought to be envied.

EXTENDED REVIEW: are you easily seduced? No, I’m not talking about an extra evening beer or a second piece o’ cake. I mean something more substantial that might change your life. Well, at least your hifi existence. My last temptation of this kind doesn’t date back that far. In the spring I’d taken the measure of the Accustic Arts Tube Preamp II and found it exceptionally suitable. Suitable? Well, the thing had everything I wanted: plenty of socketry, balanced valve circuitry, top fit’n’finish and sound to… well, just read the review. It’ll tell you why I couldn’t let it go. No cheap pleasures, mind, but worth every cent. And now the firm followed up with a fine mono amp called, simply, Mono II. Devil in a red dress? Sure felt like it.
 
Once I’d liberated the monoliths from their shipping cartons, I had a small reality check. Until now, Accustic Arts have amassed some pretty hefty stereo amp specimens in their portfolio, of the sort which pains my biceps just looking at their impressively chromed fascia inlays. On the carpeted floor of my listening room, the two monos meanwhile looked anything but monumental and closer to petit. Then their optics were dominated by heat sinks. 
 
Granted, 25 kilo per ain’t cardboard. Given the brand, it simply didn’t seem properly macho. This new understatement, I was told, ups the ol’ WAF quotient. Presumably that didn’t count for too much with their massive AMP II and AMP III stereo amps. That said, with the monos solidity didn’t go AWOL. Thick aluminium panels with the company’s signature chrome trim and a precisely machined Mono II cutout on top instantly mirror the Schwabians’ high standards. Those extend to the business end where biwire devotees are catered to. Practicality gets its due with a mute switch which enables noise-free cable swaps without powering things down. This delights a reviewer’s heart. Ditto the option to switch the monos for RCA or XLR signal input.
 
AMP II
 
Even through the jeweler’s loupe, finish and trim showed no cause for criticism. Today that’s not a given. Even the power mains was in easy reach on the front where it belongs. It’s logical that a €12’500 proposition wouldn’t play it fast and loose on perfection. And so this firm delivers. To match the sonic experience with the attractive cosmetics, Accustic Arts have called upon proven solutions. Those who’d correlate their substantial real estate of cooling ribs with solid power wouldn’t be completely wrong. The Mono II isn’t shy and delivers 300 watts into 8Ω. Even critical loads are catered to with 700 watts into 2Ω. To accompany those ratings with proper current, each channel gets a 1.2KW power toroid. Attendant filter capacitance of 80’000µF ought to be properly sufficient.
 
Accustic Arts Tube Preamp II
Valves as in the Tube Preamp II are MIA. Here the output devices are transistors and Mosfets in particular. Each channel gets 12 stringently selected parts which explains the impressive output rating. The circuitry is based on the proven well-reviewed stereo AMP II, a balanced class A/B affair with very high current output to support challenging low-impedance loads. The firm’s comment that each Mono II is essentially half an AMP II is overly nonchalant given that the surcharge over the €10’300 stereo amp wouldn’t just buy twice the casings.
 
Over the years, Accustic Arts have constantly refined their symmetrical PCB layouts. Optimised shorter signal paths led to layout changes, better parts, upgraded capacitors but also a reduction of certain filter banks for the input stage, all in the pursuit of a musical result that would be free of typical transistor artefacts. Factor in luxurious power supplies and one entertains justified cause that the yardstick for sonic excellence has been moved up appreciably and beyond just typical marketing claims. After pressing the carefully chromed power buttons, these power amps checked in for duty with a fat relay click. A few seconds passed whilst the circuits stabilised and other relays opened the gates. This process was visualised by two LEDs moving from red to blue – and not of the optic nerve-rattling type which haunted older Krells. All my signals hit the Mono II amps via my matching Tube Preamp II Mk2. Needless to say, I was most expectant to welcome such a family gathering in my own four walls.
 
To kick off, I couldn’t possibly resist cueing up Volume I of Accustic Art’s own CD production Uncompressed World. This sampler of select performers was mastered extremely carefully and with maximised dynamic range. From the first beat, the diaphragms of my Acapella La Campanella floor-standers surrendered themselves into the grip of these muscular drivers. I had no reason to question the claimed damping factor of 600 into 4Ω. The attacks of Michael Frey’s concert grand on Feathers and Flames had the type of unassailable solidity which simply eludes smaller amps. The entire stereo panorama was perfectly sorted and unbelievably stable as though cast of a mould. And that across the entire audible bandwidth. Common claims for extra authority gained by using big monos seemed well earned.
 
One of my fixed references to assess the tonal accuracy of review loaners has been the CD version of the legendary Mercury long-play record SR-90175. Howard Hanson and the Eastman Rochester Orchestra demonstrate the sound of classical acoustic instruments solo and in orchestral interplay. This album enforces very realistic impressions. My carefully practiced protocol went quickly out the window however when the Mono II showed perfect mastery over the timbre discipline. This came off so assured and self-deprecatingly that I had the tacit sense of listening to this familiar disc not with amps but through a kind of acoustic microscope. The strings evidence lovely woodiness but perhaps a bit too much so. Equally obvious? Whilst the brasses of this orchestra thunder with bravura, they miss the perfect intonation of bigger orchestras. Where I’d assigned the Accustic Arts Tube Preamp II the label of ultra-professional mastering tool well beyond just working flawlessly, the same qualities seemed to apply to the amps and not to miserly degrees.
 
It seemed child’s play for them to sort out complex timbres with great precision. When in Mozart’s Sinfonia Concertante (KV 320d) the solo violin effortlessly separates itself from the viola or in Pergolesi’s Stabat Mater the alto remains distinct from the soprano or counter tenor, it not only shapes our listening experience but points at the exactitude whereby amplifiers can differentiate between overlaid often very similar sounds. 
 
Should this conjure up anxious concerns that undue analytical keenness veers in the opposite direction of fun, I can assuage such fears by saying that the Mono II packaged insight with an exceptionally elegant liquid note that was nearly entirely free of hardness. The upshot was very pleasant and stress free, albeit at a safe distance from the romanticised homeliness of in my view mediocre valve kit. The sonic fingerprint of the Mono II reminded me more of Hegel’s big equally 300-watt rated €11’490 H30 stereo amplifier which I reviewed a few years back and then found related somehow to Tenor Audio’s 75Wi monos as my very personal references for sonic flow and elegance.
 
Let’s call it an atmosphere of intensely charged musicality. This also profited Louis Armstrong who displays an unexpectedly potent Jazz vibe on the suitably called Louis Armstrong meets Oscar Peterson LP of 1957. This is a bird of a different colour than the popular "What a wonderful world" persona of the New Orleans maestro. Here Pops swings with the ingenious Oscar Peterson on the ivories to bravura effect. This early stereo effort still surprises with its freshness and strong colours to put a lie to five decades of graying. Armstrong’s trademark voice manifested in the middle of the room with powerful sonority. And again and again there was that infectious swing. Those who would diss powerful amps for lacking nimble joie de vivre wouldn’t recognise the Mono II as belonging to the same category.
 
By then I’d detected a small tonal tell. Whilst I’ll maintain that the Mono II is very balanced and doesn’t exhibit any gross deviations, how does Radio Eriwan put it: in principle yes but. Ben Harper’s early work Fight for your mind with a well-rested Juan Nelson on the bass guitar attested to a certain faible relative to low-frequency pressure and associated blackness. Building upon such a solid foundation makes perfect sense for a muscle amp. Cue up the eponymous title track and meet a massively propulsive e-bass riff. I was surprised by how loud I could run these amps. Usually my 24m² room quits at high SPL with progressively more diffusive bass bloat. In standard living rooms not optimised for hifi, similar effects tend to kick in far sooner, at worst at subdued levels already. In this case, the tipping point at which room effects got dominant had been magically moved up by a very substantial margin. Apparently the German bricks exerted unrelenting breaking control over the drivers well beyond plain loud. And that was just fine by me. I simply hit ‘repeat’ for the same bass orgy cut.
 
Lack of an alternate preamp prevented me from sussing out how much the stable mate preamp influenced these results. What I can say is that even when connected directly to the pre-outs of my Bladelius Gondul M, the lion’s share of the described qualities—the powerfully muscular gestalt, the impressive bass registers, the molecular resolution—remained in place. What fell under the table was some of the colour intensity of the Tube Preamp II. Given the €8’000 offset, that seemed fair. If you already own a quality preamp, I see no reason why you wouldn’t leash up the Mono II to competing kit. That’s a rerun on my preamp which likewise has no compunctions to play brilliantly with gear from other makers.
 
Should you fancy a generously scaled airy rendition of the sonic action, this could well be your final address. That this won’t devolve into ill-defined nebulous excess should be a given by now. That’s easily heard with an LP reissue of the Berlin Philharmonic covering Schumann’s symphonic works. The German amps not merely cast the first-rank orchestra under Sir Simon Rattle in accurate height and width but illuminated the far reaches of the stage where the bassists and drummers labour. At €5’000 admittedly in a different range, that feat remains out of reach for my Audionet Amp 1 V2 via my La Campanella. A fairer more able competitor would be the €12’000 Devialet D-Premier which conceptually is more of an integrated amp with onboard DAC of course.
 
The French integrated unearthed a tad less air around individual performers to feel more compact. That was a matter of taste. Regardless, the Schwabian monos broke no sweat to transfer the acoustics of the Berlin Philharmonic which I’m well familiar with into my room at stout recognition factor. The highly believable dimensionality of the instruments and musicians was an extra bonus. Limited to 1’000 pressings, this 180g virgin vinyl not only attested to the Mono II’s superior spatial chops but presented them with a tough dynamic challenge. Whilst the earlier Ben Harper had already indicated the final destination, the more than 100 heads of Berlin’s premier orchestral forces ratcheted up the task at hand.
 
True, Schumann’s symphonies generally aren’t known for unbridled exhortations of dynamic violence. So I believed as well until I heard what happens when Sir Simon leads the parade. In the 3rd Rheinish Symphony for example, he develops tensional arcs which others don’t even touch upon as a faint echo. With expertly emphatic though never overdrawn pathos, the Berliners scale dramatic peaks which particularly in the third movement recalled to me the despair of Tchaikovsky’s Pathétique.
 
The Mono II retained the overview, supplied the necessary pressure during the tutti and kept sufficient headroom in reserve to follow up when the conductor demanded even more intensity. "Mission accomplished" is what I imagine Sir Simon would have sez.

With these monaural amps, temptation really can get the better of you, particularly so since all of the above didn’t just apply to the Acapella La Campanella but also Clockwork’s 2-way Event Horizon monitors. Stable into 2 ohms with sufficient reserves to set fire under the arses of sensitivity midgets, the Accustic Arts Mono II are archetypal classic muscle amps - but thankfully without the often attendant physical excess. No less compelling is their other side of finessed aesthetes with plenty of feel for musical structures, flow and the ability to not merely amplify but deliver an emotionally persuasive replay of the musical action to your speaker terminals. It’s a fact then than despite their not insignificant sticker, the Mono II do reset the yard stick plenty high. Definitely the devil in a red dress wearing Prada. Whosoever falls for it ought to be envied.

 
Psych profile for the Accustic Arts Mono II…
• they create exceptionally potent and easeful sonic conviction. The term power limit at least for halfway typical listening rooms seems merely academic.
• the mid and treble bands are poster children for neutral, uncoloured and homogenous. A bit more character reveals itself in the bass. True to the motto "dish if you can", this seemingly opened up one level lower in the bass than other amps I’m familiar with in this price range.
• though unquestionably gifted with macro-dynamics, these aren’t muscle-bound brutes. Nearly as an aside, they unravel the most gossamer tendrils and illuminate the quietest of details.
• as befits reference class amplification, they’re capable of supremely generous soundstaging. Excellent depth layering and lateral expansiveness are must haves in this class and the Mono II have mastered the space discipline.
• they also do musical flow and elegance with no transistor-reminiscent edges in evidence. Some listeners might even prefer a ‘straighter’ demeanour.
• finish and industrial design are fully up to par with the sticker.
 
Facts.
• Concept: monaural transistor power amp pair
• Power rating: 300 watts into 8Ω
• Trim: silver or black
• I/o: RCA and XLR, biwire terminals
• Dimensions and weight: 350 x 240 x 430mm HxWxD, 25kg
• Power consumption: ~100 watts at idle

..........Frank Hakopians

 
The fascinating thing about the Accustic Arts is that it offers another potent reminder that for less than stupendous sums you can construct a devastatingly good (and ultra-reliable) stereo system. It is nimble and powerful and, above all, artful.
Jacob Heilbrunn

SUMMARY: Ultimately, the warm and sumptuous sound just seemed to mate very well with analog. Often it’s alleged that German equipment has a somewhat stentorian quality to it. But I didn’t find that to be the case when it came to the Accustic Arts. Instead, I very much enjoyed the ravishing sound of strings, the evocative plangency of a solo piano echoing in the hall, and the ability to discern easily when the pedal was being applied. If you want an even greater level of fidelity than that offered by this gear—and it does exist—then you’ll have to disburse considerably more funds to attain it. As a point of comparison, my own Ypsilon gear is purer, faster, and more sweeping. But then again, the cost is markedly higher. The fascinating thing about the Accustic Arts is that it offers another potent reminder that for less than stupendous sums you can construct a devastatingly good (and ultra-reliable) stereo system. It is nimble and powerful and, above all, artful.

EXTENDED REVIEW: As heretical as it may sound, there is audio equipment that looks so attractive that sonic considerations can take a backseat, at least until you actually listen to it. The Accustic Arts gear falls firmly into this camp. Its fit and finish aren’t just appealing; they’re breathtaking. A friend of mine wanted to want to buy them based on their looks alone even before he got a chance to hear them.

The good news, however, is that the Reference Hybrid Tube Preamp II Mk II—or, as they put in German, “Der Tube preamp”—and Mono II not only look fetching but also deliver the musical goods.

As the bilingual instructions in the owner’s manuals indicate, Accustic Arts hails from Germany. Put bluntly, there is no wiggle room on products made in Germany. Germany is, of course, getting a lot of press these days for its phenomenally successful small and mid-sized businesses known as the Mittelstand that form the fiscal backbone of the country’s economy. Accustic Arts fits right in with that ethos of quality and performance.

The Accustic Arts equipment appears to be bulletproof in both reliability and performance. As its name suggests, the Hybrid Preamplifier features a mix of tubes (two 12AX7s per channel) and transistors. The unit is truly balanced from input to output, with four separate signal paths (left +, left –, right +, right –) and a four-element potentiometer to control the volume. A front-panel button allows you to choose between direct-coupled (no coupling capacitors between stages) and AC-coupled operation (coupling capacitors between stages), depending on which sounds best in your system. Three balanced and two unbalanced inputs are provided. Two variable-level outputs are included for bi-amping. A third output, this one a fixed level, can drive an outboard headphone amplifier (although the Hybrid includes a front-panel headphone jack). A theater “pass-though” allows the preamplifier to be combined with a multichannel system.

The same sort of thoughtful design appears to have gone into the power amplifier. It’s pure solid-state, delivering 300W into 8 ohms and 500W into 4 ohms via 12 MOSFETs in each amplifier’s output stage. It effortlessly powered both the Magnepan 3.7i and Wilson XLF loudspeakers. The amplifier’s diminutive size belied its power, which pretty much appeared to be limitless on either speaker—and any amp that can drive the Maggies isn’t whistling “Dixie!” The amp features a protection circuit that will trip if the amp is clipping, or if it detects DC offset from the preamplifier, the latter phenomenon something that can crater your loudspeaker’s drivers.

On both digital and vinyl I was impressed by the preamp and amp’s silky midrange and the wealth of detail they produced. Mated together, they definitely supply a sound that lands firmly on the tube side of the sonic spectrum. The preamp is a balanced hybrid design that takes several minutes to warm up. I would emphatically suggest that the amp needs several hours before it sounds its best. Upon startup it will appear to be a bit grainy and compressed. These qualities vanished after a few hours.

In keeping with the balanced design, I used a pair of Ypsilon transformers to create a balanced signal from the cartridge on my Continuum Caliburn turntable to drive the preamplifier’s balanced inputs. From the dCS Vivaldi I used Nordost Valhalla 2 cabling, as I did for the speaker cables as well. The balanced design helped to ensure that there was no audible noise or hum. In fact, even when I ran the amplifiers in single-ended mode from the Ypsilon preamplifier, I was pleased to note that there was also no hum or buzz. Accustic Arts gives you the option of switching off the tubes via a button on the front panel to save on precious tube life.

Like most manufacturers, Accustic Arts makes much of its wide bandwidth and low distortion, and those qualities were in evidence on both CD and vinyl playback. The equipment sounds extremely linear with no part of the frequency spectrum appearing to be overemphasized. It is this very linearity that may strike some listeners as producing a sound that is staid, but it is not. Rather, the Accustic Arts equipment is non-fatiguing and engaging, though it definitely has its own sonic hallmark.

Right from the outset, I was bowled over by its reproduction of a Pablo album featuring Oscar Peterson and Jose Pass playing Porgy and Bess. I’m not sure that I could actually recommend that anyone rush out to procure this album, as the combination of clavichord and acoustic guitar is somewhat peculiar. But it’s certainly an enjoyable lark and the Accustic Arts preamp and monoblocks did a sterling job of capturing the timbral nuances of the clavichord, which first surfaced in the Middle Ages and possesses metal blades known as tangents that strike the strings. Each note was clearly rendered; it was possible not just to hear the clavichord but into the instrument itself, to the point where you could hear how the reverberations were being created. Particularly noteworthy was the large and sonorous soundstage the preamplifier conveyed—the sense of acoustic space was about as good as it gets. Throughout, the interplay between Peterson and Pass on this exotic album came through beautifully.

The same can be said for another album that’s been in heavy rotation recently—a marvelous Angel LP of Kathleen Battle and Christopher Parkening. Several songs by the Renaissance English composer John Dowland may sound simple, but Battle and Parkening bring them to life with great precision and emotion. Battle’s pure and radiant voice was precisely captured by the Accustic Arts. So was Parkening’s fine guitar work. On the Bach/Gounod Ave Maria, the very low noise floor of this Teutonic equipment allowed Battle’s silvery vibrato to emerge as though from nowhere. Spooky.

What about the big stuff? Was the Accustic Arts able to hack it on orchestral powerhouse numbers? On a London recording of Julius Katchen playing Liszt’s Concerto No. 1, the piano was solidly grounded in its own space while the orchestra was spaciously arrayed with each section clearly delineated. The preamp and amplifier had no problem producing orchestral fortissimos and the piano never became swamped by the London Philharmonic. All that amplifier power, for example, allowed the Wilson XLFs to belt out trombone choruses with tremendous vividness and punch.

Still, in this era where everyone seems to be chasing neutrality, it was readily apparent that the Accustic Arts gear does have a sonic signature, a somewhat emollient approach to reproducing music. There’s never going to be a hint of stridency or rebarbativeness with it. Rather, it focuses on the midband, offering a full and slightly dark sound. Take a CD that, if it were an LP, I probably would have worn out by now, Mavis Staples’ One True Vine [ANTI-]. Even in her seventies, Mavis can belt it out like few other singers and her impassioned, full-throated voice came through clearly on cuts such as “I Like The Things About Me.” The backing choruses on the album were always clearly audible but slightly softened. The same went for the bass lines. Cymbals displayed a fine alacrity and clarity, while electric guitars sounded fuzzy and powerful. Distorted? Well, yes. But the truth is that there is a lot of distortion in their sound on this album.

The careful ministering to the treble that the designers of this equipment carried out is also clearly audible on a Delos CD with the flautist Joshua Smith, who performs the Bach’s sonatas together with harpsichordist Jory Vinikour. This is sterling playing by both, and I was struck by the control and limpidity of the sound, especially in the treble region, of the Accustic Arts. Everything was rendered just so, creamy and unflappable, tranquil and poised.

Ultimately, the warm and sumptuous sound just seemed to mate very well with analog. Often it’s alleged that German equipment has a somewhat stentorian quality to it. But I didn’t find that to be the case when it came to the Accustic Arts. Instead, I very much enjoyed the ravishing sound of strings, the evocative plangency of a solo piano echoing in the hall, and the ability to discern easily when the pedal was being applied.

If you want an even greater level of fidelity than that offered by this gear—and it does exist—then you’ll have to disburse considerably more funds to attain it. As a point of comparison, my own Ypsilon gear is purer, faster, and more sweeping. But then again, the cost is markedly higher. The fascinating thing about the Accustic Arts is that it offers another potent reminder that for less than stupendous sums you can construct a devastatingly good (and ultra-reliable) stereo system. It is nimble and powerful and, above all, artful.

Throughout the years I have heard many great amps of different topologies and most of them were special in one regard or another but never offered so COMPLETE and OVERALL musically SATISFYING performance.
SUMMARY: ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 represent such a potent combination that leaves a lingering reference status and with the requested prices for both MonoII and Tube Preamp IIMK2, show a value that it’s not only hard to match, but quite unlikely to match.
The Accustic Arts trio could drive every speaker I have tried with absolute ease, however in combination with the SoulSonic Impulse speakers the ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 managed to create something special that operates at the level imagined by few. This combination reproduces the music at the “cost no object/au plus haut niveau” and brings a refreshing statement in the world of high-end audio.
When both ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 are working closely in a system with the SoulSonics Impulse speakers, they embrace the music and reproduce it with such realism that this must surely be widely acknowledged. And as such they are the recipients of the Upper Echelon Mono & Stereo award for not only being the state of the art audio products but also for being music machines capable of bringing the full emotional content hidden in the music grooves... and thus being able to satisfy the most discerning ears and highest demands. 
EXTENDED REVIEWL I’ve stumbled upon the Accustic Arts components through Walter Kircher, their sales agent. We’ve exchanged quite some emails and messages that eventually led to the first Mono & Stereo and Accustic Arts special listening event.

The complete Accustic Arts system grabbed my attention and eventually I got an opportunity to experience in-depth their MONO II power amplifiers, Tube Preamp IIMK2 and Tube DAC II. 

In this test and review I’ll be focusing on the MONO II power amplifiers and the Tube Preamp II in trying to bring the best insights.

I’ve had a pleasure to hear both the MONO II power amplifiers and the Tube Preamp II in my own reference setup as well as with the state of the art SoulSonic flagship Impulse speakers. This combination brought out the best of Mono II power amplifiers and Tube Preamp II and I will mostly focus on this dedicated combination as it represents a state of the art system that is capable of really impressive reproduction in the EUR 200.000 region of systems pricing scheme.

Let us first take a look into the technical side of both units.

MONO II highlights (per monoblock):
Reference class mono power amplifier
12 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: 1200 VA (watts)
Optimum smoothing thanks to more than 80,000 µF power supply capacity; Premium quality capacitors (“Made in Germany”)
Very high damping factor for perfect speaker control
Professional protective circuit against clipping, HF oscillations and too high DC offset
Constant low operating temperature due to generously dimensioned heat sinks
Balanced input (XLR) and unbalanced input (RCA) – the inputs are switchable on the rear panel
All used parts and components are selected and of highest quality
Premium quality, gold-plated bi-wiring / bi-amping speaker terminals
Mains power switch on the front panel
Extremely stable and resonance optimized, massive aluminium housing; inlay made of massive, high gloss polished and chromed brass
ACCUSTIC ARTS® MONO II is “Handmade in Germany”

ACCUSTIC ARTS® MONO II power amplifier is the first MONO output amplifier from ACCUSTIC ARTS and the latest addition to the ACCUSTIC ARTS® family of power amplifiers. MONOII DNA is based on the company already established AMPII, which already found many happy homes around the world.

ACCUSTIC ARTS MONOII continues the company “leitmotiv” design in timeless Bauhaus shape that clearly radiates a special aura which can stand the test of time and can actually aesthetically please and carry on with all generations.

From the ground up MONOII is designed as an optimised high-performance power amplifier. ACCUSTIC ARTS technical team strictly focused on the short distances in the circuits and with the selection of finest components. As a rule in the upper echelon of power amplifiers every electronic part is strictly selected and measured for maintaining the best tolerances. But this doesn`t stop at the technical level, namely, ACCUSTIC ARTS is one of the few companies that strongly advocates the listening fine tuning, along with an urge for technical perfection. MONOII feels like Made in Germany product from the first glance, but behaves beyond expected in sound performance. It transcends the way typical German high-end components sound (precision above emotion) and welcomes the radiant, emotional impact.

Before delving deeper, what makes MONO II exceptional performers? As already mentioned the first thing is surely the selectivity of the materials, next comes strong, potent power supply. Made in Germany, this strong toroidal transformer with 1200 VA rating, a special core and additional Mu metal shielding along with 12 hand selected MOSFET output transistors and 8 large power supply capacitors (10.000 µF) manufactured in Germany to ACCUSTIC ARTS` exact specifications, ensure the amp can deliver thunderous power with ease and without any struggle. This helps in presenting the music with natural flow and without dynamic constraints.

What does this mean in earthly language? Properly sized and refined power supply is something not too many high-end audio designers are paying enough attention to. Another thing is how gain stages work and how and where the signal is attenuated. Like with my reference Robert Koda Takumi K–10 preamplifier (27.500 EUR), at the highest operating level the electronic components are hardly pushed to the limits and they can keep the distortion levels down. This is an open secret that only few designers fully understand but it brings out the music reproduction on the reference level. DartZeel uses this in its own way but basically employs the similar principle.

The heart of ACCUSTIC ARTS MONOII is certainly its very high current capability coupled to a really fast and responsive power supply that gives an incredible control of all speakers and loads. I cannot stress enough the importance of a FAST and POWERFUL power supply for realistic music reproduction but this is obviously something Mr. Martin Schunk, the Accustic Arts electronic designer knows extremely well.

MONO II is also designed from the ground with enough room to keep the air flow and let the circuits ventilate at the best temperate point, without bringing the performance levels down.

ACCUSTIC ARTS PREAMP II MK2 HIGHLIGHTS

Audiophile reference preamplifier with a so called “tube hybrid” concept and 4 military tubes (2 tubes per channel)
Fully balanced circuit design from input to output
Advantages of this “tube hybrid” technology:
- very high impedance
- very high bandwidth
- very low distortion factors and a “good-natured” distortion spectrum
- “analog” and very precise sound performance
- 4 separated amplification paths, which are not influencing each other
Easy change of tubes without any adjustments just “plug and play”
Professional Class A output stage using technology derived from studio engineering
All used components are of outstanding quality (e.g. Burr Brown® OPA 627) and additionally selected; all relays have high quality gold-plated contacts
4 high precision military tubes; 4-times selected
4-channel volume potentiometer for best crosstalk
3 x fully balanced high level inputs (XLR) and 2 x unbalanced high level inputs (RCA)
1 x unbalanced input (RCA) configured as “SURROUND-BYPASS”
2 x fully balanced outputs (XLR) – 1 x AC coupled, 1 x DC coupled
2 x unbalanced outputs (RCA) – 1 x AC coupled, 1 x DC coupled
1 x headphone output, switchable (1/4" stereo female jack)
1 x unregulated, switchable output for the connection of an external headphone amplifier (RCA)
Phase switch for 0° and 180°
2 magnetically shielded, encapsulated 75 VA toroidal core transformer (“Made in Germany”) of premium quality for high output reserves
Front panel, cover and remote control are made of massive and solid aluminium; turning knobs made of massive and chromed brass
ACCUSTIC ARTS® TUBE PREAMP II – MK 2 is “Handmade in Germany”

MADE IN GERMANY
ACCUSTIC ARTS are clearly proud of their Made In Germany signature. Both MONO II and TUBE PREAMP II are exclusively manufactured in ACCUSTIC ARTS premises in Lauffen am Neckar, Germany. As an important part the company states:

“The development, component insertion of PCBs and final assembly takes place in Germany and all housing parts and many individual components are sourced from long-term suppliers based in the south of Germany. Our specially trained and experienced technicians build this high-end audiophile amplifier from a large number of individual components.”

A sudden burst of life energy!
Although there may be differing opinions among audiophile crowd in regard to the order of importance of all components in the reproduction chain, the fact remains that amplifiers play the VITAL ROLE in all systems that are aiming for the ultimate in sound quality levels. Like with every component there are technical requirements and of course, sonic requirements. With amps, the technical requirements address the target electrical power levels and things like stability, dynamic headroom, etc.

If we agree that the sound of live, un-amplified instruments and voices contains the highest levels of dynamics (dynamic swings) that at the present our high-end audio systems can only approach to some point, but never fully reach, then we are starting to realize the immense challenges each high end audio amplifier designer is confronted with.

Electrical power (static power) is one thing and dynamic responsiveness (dynamic power) is another, but of course, they are related. Just from the technical standpoint one could assume the size of the power supply plays the biggest role here, but aural experience tells us there must be something else at work that is at least equally important. True, weak power supply doesn`t help here, yet after listening to numerous high quality amps I cannot help but conclude that the power supply responsiveness plays a critical role in this regard. I have heard numerous power amplifiers with monstrously over-sized power supplies but many of them lacked speed, control and authority, sounding dead, not alive. In the ultimate sense we are aiming for instant transient responsiveness and here I have noticed big differences among amps. Some are voiced for transparency, some for smoothness, some for neutrality (whatever that means), others for natural tone colors, etc. 

Bringing all the desired traits under one hood is not a trivial task. If we aim for those elusive live sound quality levels, then we have probably noticed, how besides micro and macro dynamics, live music possesses a kind of sound authority (weight) that even many of the really expensive audio systems fail to convey…and this is the second prerequisite for anywhere realistic sound reproduction.

UNDERSTANDING THE PURSUIT OF HIGH-END 

The preamps (or preamp sections in integrated amps) are supposed to deliver a signal that a power amp will give a meaning to. Of course there are power amps that are very (input signal) sensitive and might need just an attenuator but that is not the subject of this review.

If we understand the term HIGH END AUDIO literally then we are probably aiming for the absolute: wanting to get as close as possible to what we hear at live musical events. Of course END doesn`t mean we can get identical sound quality levels with high end audio equipment (nothing ever ends) In this case it just means we’re not interested in merely »good« sound.

The aforementioned »authority« (subjective weight) of the live sound is placing BIG demands on all components in the audio chain and is also showing the biggest differences among amplification. Sometimes it seems it is easy to achieve incredible transparency in the reproduced sound (not that it really is) and I have witnessed it many times, with high quality audio systems. Some components (or a combination of components) are like magnifying glasses, they can highlight tiny details in a way that cannot be heard with a live played instrument or a human voice. Although this might be attractive to some listeners – it is not a step closer to the live sound but a step away; we are substituting the real quality for an artificial one.

To make a reproduced music anywhere more realistic, we need to ensure the system will be able to preserve this AUTHORITY of the live sound as much as possible otherwise the reproduction will NEVER BE reminiscent of the REAL THING.

OK, so this brings us back to the subject of this review, the fabulous ACCUSTIC ARTS TUBE PREAMP II – MK2 and the ACCUSTIC ARTS MONOII monoblock power amps. Potent trio that excels precisely in the most difficult to reproduce areas: micro/ macro dynamics and authority of the sound – among many, many other things.

Throughout the years I have heard many great amps of different topologies and most of them were special in one regard or another but never offered so COMPLETE and OVERALL musically SATISFYING performance.

To begin with, the ACCUSTIC ARTS combo is able to drive ANY speaker with astonishing control, authority, showing incredible dynamic swings, fantastic levels of transparency, proper tonal colors, soundstage delineation and overall believability. That was a really short description. Now let us dig deeper.

My encounters with SoulSonic speakers, open baffle dipoles with tall ribbons showed me they have some special qualities that even lesser amps are able to reveal but it was only with the ACCUSTIC ARTS TUBE PREAMP II – MK2 and ACCUSTIC ARTS MONOII that I began to discover and fully appreciate all their virtues.

For instance, the lower and upper bass had qualities that just gave a much more convincing impression of the real thing. The beat of a kick drum was reproduced with a tremendous, uncompressed punch but the absence of box gave it a really lifelike feeling which was enchanting. Various big acoustic instruments like the big Kodo drums, upright basses or even pianos had a sense of authority that is rarely heard. This authority means the sound was powerful, dynamic and controlled at the same time; no instrument or voice was thinned or robbed of its weight. The piano, a very difficult instrument to reproduce, in particular sounded very dynamic and lifelike in its character. The instruments covering the midrange frequencies had a great definition with just the right timbre (especially with Skogrand Beethoven and Vovox Textura Fortis speaker cables). The solo vocals or choirs had tremendous clarity and natural, dense tonal colors with captivating openness that made the whole aural experience very intimate and called for prolonged listening sessions.

The guitar player`s chord movements were easily heard, yet still not highlighted in a negative way. They were just referenced according to how they were recorded.

The transparency was exemplary and this among other things led to a very holographic impression of the instruments placed on the imaginary soundstage.

The energy produced in live music was preserved extremely well; the reproduction was vibrant, immediate and ensured an incredibly emotionally dense and musically involving experience – a true rarity nowadays.

The combo showed no preferences for any musical genre, everything was reproduced coherently, stressless and very natural. Bad recordings were easily revealed, but not in a way that would diminish the musical enjoyment – quite on the contrary, for anyone who is a music lover first and foremost, this could be a dream system, with it, one could listen for all day long (even very loud) without any listening fatigue or sense of boredom.

I should mention that I have briefly tried to substitute the ACCUSTIC ARTS TUBE PREAMP II with some other preamps that I have had on hand. With the exception of Robert Koda Takumi K10 preamplifier none of them was able to serve the monoblocks in a proper fashion. The sense of energy and body was mostly lost and this further showed how difficult it is to find a proper preamplifier/power amplifier pairing.

CONCLUSION

ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 represent such a potent combination that leaves a lingering reference status and with the requested prices for both MonoII and Tube Preamp IIMK2, show a value that it’s not only hard to match, but quite unlikely to match.

The Accustic Arts trio could drive every speaker I have tried with absolute ease, however in combination with the SoulSonic Impulse speakers the ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 managed to create something special that operates at the level imagined by few. This combination reproduces the music at the “cost no object/au plus haut niveau” and brings a refreshing statement in the world of high-end audio.

When both ACCUSTIC ARTS Mono II power amplifiers and Tube Preamp II MK2 are working closely in a system with the SoulSonics Impulse speakers, they embrace the music and reproduce it with such realism that this must surely be widely acknowledged. And as such they are the recipients of the Upper Echelon Mono & Stereo award for not only being the state of the art audio products but also for being music machines capable of bringing the full emotional content hidden in the music grooves... and thus being able to satisfy the most discerning ears and highest demands. 

These power plants provide an impressive 300w @ 4ohms & 500w @ 4 ohms. Combining that much power with such a smooth, coherent sound is really something special. My greatest respect!
DIRK SOMMER

STATEMENT
The Accustic Arts look great and are excellently finished. They sound the way you want it from a small, fine high-end power amp, but they are not: These power plants provide an impressive 300w @ 4ohms & 500w @ 4 ohms. Combining that much power with such a smooth, coherent sound is really something special. My greatest respect! What did you say about the Mono III ...with 600w @ 8ohms?

EXTENDED REVIEW: Accustic Arts, the tradition-steeped company from Germany's south-western region of Swabia, is celebrating its 20th anniversary this year. While quickly gaining a good reputation in the Far East and also being there commercially successful, the prophet remained less prominent in his own country. As the Mono II prove, the products surely are not the ones to blame.

It was the former company management that held responsible for this by primarily having focussed on the export business. Then two years ago, Hans-Joachim Voss bought the company, and, of course, took the export business further on. In a second step, he is now concentrating on the German dealerships. And for this purpose he was able to win an experienced sales professional: Werner Möhring, also known as a member of the German distributor company “G8 And Friends”. Hans-Joachim Voss charged an open door when he suggested that I could again busy myself with gear from Accustic Arts: My positive attitude towards the company isn’t mainly based on the fact that right from the start the Swabians have had a great affinity to the recording scene and especially to sound engineer Milan Sajé, in which they found an experienced consultant, who not only works on his own or in Accustic Arts’ premises, but also for the renowned recording studio Bauer in Ludwigsburg. Milan Sajé accounts for the production of the five albums, "Uncompressed World Vol. I to Vol. V", released through Accustic Arts Audiophile Recordings, some of which are also available on vinyl. No no, even though I intensively shop-talked with Milan Sajé during my visit to Laufen in 2008 – by the way, I really do not have to be convinced of compression-free recording techniques – and though I could acquire a technical rarity from him at the time, it principally are the components, which have been justifying my positive attitude to Accustic Arts: Shortly after having done a company visit and a report thereafter, I had the opportunity – and the pleasure – to employ myself with the Accustic Arts Drive II and Tube DAC II. The mechanically immensely elaborate transport with its 18 kilograms of weight and the converter with the then quite unusual 32-bit signal processing technology and its tubed output section really wielded a sonically very lasting impression on me.

But let's just go back to the Mono II, the second-largest amplifier in the Swabian's reference line, which I have chosen because its opulent output power range of 300 watts at eight and 500 watts at four ohms is more than enough for my system's requirements. However, in contrast to the 60 kilograms of the top model Mono III, the Mono II only weighs "amicable" 25 kilograms. The discussion with the designer revealed that the Mono II despite its XLR input is not a balanced amplifier in its own right. If one selects the balanced input, the signal is converted to an unbalanced signal using IC from Burr Brown and then treated in the same way as the input signal through the RCA input. One could now begin to hotly dispose of the signal through the RCA output of Einstein ' s fully balanced The Preamp, bypassing AccusticArts' un-balancing circuitry or benefiting from the less susceptible balanced signal routing. Einstein's The Poweramp with the Two Mono II Accoustic Arts, I will excuse myself from further musings on the matter.

After having passed the RCA input respectively the un-balancing circuitry, the signal is fed into a Burr Brown class A current amplifier. As high-frequency transistor is used, which at the same time defines the relatively high current current and the DC zero point for the twelve MOSFET power transistor selected in the same way. The power amp produces at astonishingly small percentage of distortion. In addition, 99% of the distortion spectrum of K2, aka harmonic distortion, which the ear perceives as pleasant. For the protection circuit, he defined a specific frequency curve in order to make a DC obsolete. Capacitors in the signal path he omitted as well. The capacitors next to the signal path are FKPs or polypropylene foil capacitors from Wima with a maximum tolerance of one percent. Except for the source and boucherot resistors, only metal film resistors are used with a tolerance of one percent are. All source resistors come up with low-inductance metal band versions with ceramic housings.

A considerable effort is thus applied to the power supply. The 1,200 VA toroidal main transformers according to the present invention is disclosed in the US patent application Ser. No Stage, as well as the input and driver stages. Their share of the total capacity of more than 80,000 microfarads is multiplied by a newly developed capacitance multiplier circuit similar to a gyrator. Ultra-fast switching diodes are used for rectifying both voltages. Although the Mono IIs admittedly have a high damping factor, it is not the absolute value - this is between 400 and 1000, linearly beyond the audible range. This makes the work for the connected loudspeakers a lot easier.

Whereas my own work turns out to be a bit more strenuous when moving the quite heavy mono blocks from the photo studio into my listening room. However, these physical efforts quickly get rewarded when the first tones emerge from the still cold Accustic Arts monos: It is already audible that the monos will fit into my system seamlessly. There is no irritation, no irregularity. After all, this cannot be taken for granted, as all the components within my system, including a wide range of accessories, have been matched and harmonized for years. Before finally comparing them to my normally used power amplifiers, the Accustic Arts very much pleased my life for quite some time. They perform in such a right and familiar way, that I, without having to think about it, rely on them when testing the Aqvox Detoxer. On one hand, they set to work with high resolution, which makes working with them an extraordinary experience, and on the other hand, they act so harmoniously and homogeneously, that one wants to listen to them for mere pleasure. In the course of time, a further noteworthy detail comes to my mind: the monos real have a good grip on the woofers of the Kawero!, which must in no way lead to the impression of a somewhat more slender bass foundation. On the contrary! The Mono II combines the best of both worlds: lots of energy and precise control.

I must say that I already forgot about the fact, that the Accustic Arts monos had been responsible for my chain’s powerful performance, when I played Helmut Baumgartner a few recently rediscovered rock songs before he addressed his studio work. However, the amplifiers delighted him much more than the harsh, barely audiophile rock sounds – and that for a reason that seemed to have lost my attention because of the successful integration of those monos in my system: The ones from Accustic Arts are different from the Ayons with their nominal 150 watts or from Einsteins The Poweramp with its 140 watts, both into 4 ohms, being comparatively true power packs with their 500 watts at 4 ohms. In practice, however, when increasing the power rating of solid-state power amps, it at the same time gets increasingly difficult to have them sounding smooth and harmonious also in the high-frequencies, wherefore Helmut Baumgartner got extremely positively surprised by the finely resolved, yet entirely stress-free and enjoyable high-frequencies, in light of the Mono II’s interior with its twelve power transistors and the mighty toroidal mains transformer. I like to admit that I headed for the Mono IIs without any expectation – or should I better write: quite naive? Having heard my colleague’s comment, I suddenly had to think back with frights to the review of the gorgeous Göbel Epoque Fine, whose impedance drop put the Brinkmann monos used for amplification at that time out of range. The replacement amps, which were then hastily cobbled together to complete the pending final sonic impressions, were probably the strongest and most expensive amplifiers that ever found their way into my listening room. They had an easy play with the Epoque, but by no means they were able to reach the musicality of the stressed Brinkmanns. Since then, I nurtured a certain skepticism about extremly powerful amplifiers in general. The Mono IIs, however, I gave a listen even before I occupied myself with their technical specifications. They simply sound like extraordinary delicate power amplifiers paired with a moderate power rating – despite their specs showing those impressive 500 watts. Awesome!

Before starting the comparison with The Poweramp, I take care in putting up the best possible working conditions for the Accustic Arts monos: Since they source their power, like all other power amps in my listening room, through the tried and tested power cables from Swisscables Reference Plus there is no other field of play left than to improve the positioning on the floor. At present, the Harmonix Beau Tone Million (TU-666M) rank as my favorites. Up to now, they have managed to lift all used power amps to great sonic heights. But one of the two sets that I have in my possession, I use under the Kawero! Classic, so I switch to the second best in my list of favorites, the Beau Tone (TU-666ZX). While the Mono IIs are placed directly on the tiled floor, Arild Anderson's "If You Look" from the album If You Look Far Enough enthuses with richly colored percussion instruments, powerful kettledrums and perilous sounding electronic sounds. The Hamonix feet, though, help them to a much wider and somewhat deeper virtual soundstage. The distinction between the smaller bells, bigger bells and rattles now works out even better: The instruments seem to be playing in the room, the speakers vanish and cannot be located anymore. Truly good!

In comparison with Einstein's The Poweramp there is not much of a quality difference, the sonic discrepancies linger in the range of nuances: The Poweramp performs a touch faster and minimally warmer, while the acoustic arts manage to open up a soundstage at least as large and open, if not more widely spaced. The solid-state monos in indulge with minimal pressure and control in the lows, but the temperature in the recording room seems to be one or two degrees lower. As you can guess, this is about very subtle matters of taste. Einstein's are ready to offer. I must say, I am perfectly happy with both!

STATEMENT
The Accustic Arts look great and are excellently finished. They sound the way you want it from a small, fine high-end power amp, but they are not: These power plants provide an impressive 300w @ 4ohms & 500w @ 4 ohms. Combining that much power with such a smooth, coherent sound is really something special. My greatest respect! What did you say about the Mono III ...with 600w @ 8ohms?

Awards

STEREO JAPAN - Best Products of the Year Award 2015

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