Accustic Arts Audio Mono II monoblock power amplifier

Accustic Arts of Lauffen, Germany, was founded in 1997 by Fritz Schunk, who sold the company to Hans-Joachim “Jochen” Voss in 2016. Voss’s professional background had more to do with sweet spreads than sweet sounds—he spent 20 years doing sales and marketing, including with the Ferrero Group, which produces Nutella—but he happened to own some Accustic Arts components, and as a music-loving consumer with a special fondness for rock, had been in touch with Schunk for many years before the company went up for sale.

In an extended Skype conversation with Voss and Sebastian Ruhland, a technician at Accustic Arts, I learned that the 55lb, 300W (into 8 ohms), solid-state Mono II ($24,900/pair) was released six years ago but has been unavailable here for much of that time, owing to a lack of distribution: It and the company’s other products have only recently been brought to the US market. Incidentally, the Mono II’s predecessor, the 121lb Amp II stereo amplifier, has been a company staple for almost two decades, while the larger Mono III, a far heavier (132lb) and higher-powered (650W into 8 ohms) mono amplifier, came out in 2016.

According to Voss and Ruhland, Accustic Arts amplifiers are improved over time; the Mono II’s most recent upgrade involved a change to the toroidal transformer core to deal with hum issues that developed in countries with widely fluctuating voltage. “We optimize the product all the time,” Voss said. “For example, we recently upgraded the circuit boards without telling anybody. If we changed the amp’s name with each improvement, it would be Mk. XX by now.” If you’re shopping for a used Mono II, be sure to note the serial numbers and check with the company to confirm its provenance.

The Accustic Arts website says that the Mono II includes 12 “selected” MOSFET output transistors; a magnetically shielded and encapsulated toroidal-core transformer with a capacity of 1200VA; more than 80,000µF of power-supply capacitance; a “very high damping factor for perfect speaker control”; capacitors by Fischer & Tausche, from the northwest corner of Germany; “generously dimensioned” heatsinks; and two pairs of gold-plated speaker terminals, for biwiring. In addition, Ruhland said, “To drive the MOSFET amplifier, we use a current mirror, in which the same current that flows through one transistor also flows through the other.

“We don’t use the voltage amplifier to drive the MOSFET; we use the current mirror. I have not seen that very often—only one company does it somewhat the same way. Using the current mirror, you don’t need MOSFET driver ICs that make more noise and add distortion. Using the current mirror lowers distortion and raises signal-to-noise ratio.”

Installation and setup
After I recruited a friend to help move my 125lb reference Dan D’Agostino Progression Mono amplifiers out of the way, setup was simple. Positioning the Mono IIs on my Grand Prix Monaco amp stands was easily accomplished, as was attaching the same Nordost Odin 2 balanced interconnects, speaker cables, and power cables as I use with my reference amps. (While I did try the surprisingly thin, molded-plug AC cords supplied with the Accustic Arts amps—see below—I stuck with my reference Nordost Odin 2s for 99% of my listening.) Given that the amp’s speaker lugs are easy to loosen and tighten, and that the two sets of speaker terminals are identical, you need only make sure to attach your speaker cables in phase and depress the Input Selection button on the monoblock’s back panel to the correct position (Balanced/XLR or Unbalanced/RCA).

The handsome front panel includes three LEDs, used to indicate whether the powered-up Mono II is in warm-up mode or ready to play; once you depress the sole on/off button—there is no standby power switch on the amplifier’s rear—the light show lasts five seconds and then the amps start producing sound. I always reserved at least an hour for warm-up, which I hastened by playing demagnetization and break-in tones from my Nordost System Set-Up & Tuning CD.


I asked Voss about power conditioning during our Skype interview. “It’s up to you,” he told me. Ruhland noted that in some locales, large voltage swings or DC offset on the line—or a proximate hair salon—could make a power conditioner necessary: “When you use a hair dryer next to your amp, maybe you’d better use a power conditioner.” Even though my system gets its AC via a dedicated 8-gauge line and special AudioQuest outlets, experience suggests that the music room’s second breaker panel picks up noise from both the panel in the main house and the transformer in the street. So for most of the review, I plugged the Mono IIs into the same AudioQuest Niagara 5000 noise-dissipation system fed by the same AQ FireBird HC power cables I use with the Progression Monos.

Although Voss confirmed by email that the amps had been broken in at the factory, Accustic Arts’ US rep, Randy Forman, told me that, in his experience, an extra 100 hours was needed. I played break-in tones 24/7 for five days. I encountered just two issues with the Mono IIs. The first was minor: The on/off buttons didn’t always depress smoothly. Although neither ever got stuck, they felt a bit chintzy. More concerning, the left-channel amp began to hum audibly on my last day of listening and continued to do so even when I removed it from the Niagara 5000 power conditioner and plugged it into the wall outlet. I checked to see whether appliances were running full force in the main house—the eightfold assault of washer, dryer, dishwasher, electric range, refrigerator, heat pump, and two computers—but the three wire-haired terriers had once again failed in their ongoing attempts to turn everything on and burn down the house. (They love the chorus of Aretha Franklin’s “Think,” which they bark in cadence, but have yet to embrace the notion of “Respect.”) Perhaps John Atkinson’s measurements will detect what the hum was about.

Yippee, it’s time to listen
Because I review music for Stereophile, my first listens were to unfamiliar recordings. Lacking a baseline reference, I may have been a bit at sea, but that didn’t stop me from loving what I heard. The clarity, beauty, and exceptional smoothness of Jim Anderson’s engineering revealed itself as I auditioned Patricia Barber’s Higher (our September 2019 Recording of the Month). The glorious voice of soprano Lise Davidsen singing Wagner and Strauss (24/96 WAV/ProStudioMasters, Decca B003030802) sent me into an ecstatic whistling frenzy, and I was deeply moved—chilled—by the suffering and grief that sang through the recording, by Mirga Grazinytè-Tyla and the City of Birmingham Orchestra, of Weinberg’s final Symphony, No.21 (24/96 WAV, Deutsche Grammophon). And if I didn’t wax ecstatic about the recording by Sasha Cooke, Kelly Markgraf, conductor Steven Osgood, and the Fry Street Quartet of the chamber opera As One (24/96 FLAC), that was due solely to the music—not the sonics.

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Accustic Arts Audio GmbH

US representative: Finest Fidelity

3 Sagebrook Drive

Bluffton, SC 29910

(386) 341-9103


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