Viola Labs Concerto Amplifier

Up for sale is a Viola Labs Concerto power amplifier in excellent condition.Also have a Crescendo preamplifier for sale on another listing.This Duo are one of the best sounding Power and preamplifier I've ever had.
The Absolute Sound Editors choice 2015.
Read the review:Speed, resolution, and transparency are often accompanied by a tendency toward leanness, lack of body, thinning of tonal colors, and a bottom end that favors precision over visceral weight. That was not the case with the Concerto and Crescendo. In addition to a full-bodied tonal balance, the Viola pair’s bass was phenomenal. These electronics combined deep and effortless extension at the extreme bottom with a visceral muscularity in the midbass that created a powerful physical involvement with the music. The huge left-hand chords in the previously mentioned Nojima Plays Liszt were thunderous and spine-tingling. The Concerto seemed to have an iron-fisted control over the Magico Q7’s woofers, showcasing this speaker’s remarkable combination of pitch precision, lack of overhang, extension, and sheer bottom- end verve. Despite its rating of “only” 100Wpc, the Concerto sounded like a powerhouse, with no softening of bass drum impact at high playback levels or any sense of dynamic compression. The only other amplifiers I’ve heard in my own system with this quality of bass were the Jeff Rowland 725 monoblocks I reviewed in Issue 228.

These impressions were made listening to the Concerto and Crescendo being fed analog signals from a dCS Vivaldi, Aesthetix Romulus CD player/DAC, and my LP front end. How does the Crescendo’s integral DAC sound? I connected my MacBook Pro running iTunes and Pure Music to the Crescendo via USB, and alternately to the dCS, and Aesthetix, with the dCS and Aesthetix feeding the Concerto’s balanced analog inputs. I found the Crescendo’s integral DAC to be excellent, but not at the same level of achievement as the Concerto and Crescendo’s analog circuits. The Concerto and Crescendo are so good that anything less than a superlative source prevents them from achieving their full potential. The Crescendo’s DAC was fairly dimensional, clean in timbre, and wide in dynamics, but it did impart a bit of hardness and sheen to the treble, along with a reduction in transparency and immediacy. The exquisite, finely filigreed top end which sets these electronics apart as special was still apparent, but not to the same degree as when the Crescendo was fed an analog signal from the Aesthetix or, especially, the dCS. If the Crescendo and Concerto weren’t so spectacular, the DAC wouldn’t have come under such a critical ear.

Conclusion
The Viola Audio Laboratories Crescendo and Concerto are simply stunning musically, and among the best electronics I’ve heard. The transparency, the sense they convey of nothing coming between you and the music, their sensational treble resolution without a touch of the analytical, their wide dynamic expression, and their absolutely sensational bass vault the Viola electronics to world- class status.

Throughout this review I’ve felt the urge to temper my praise of these electronics only because these are the company’s “entry- level” components—what are Viola’s $69,000 Spirito preamplifier and $59,000 Legacy 100W pure Class A monoblocks capable of? It’s mind-blowing to consider that one of the following statements must be true: 1) the Crescendo and Concerto are very close in sound quality to Viola’s reference-level products; or 2) Viola’s top- of-the-line electronics are in a league that I’ve never experienced.Concerto Stereo Power Amplifier
Power output: 100Wpc into 8 ohms, 200Wpc into 4 ohms
Inputs: One balanced on XLR jacks, one unbalanced on RCA jacks
Viola Local Network (link bus): CAT-5
Dimensions: 17.5" x 3.5" x 15"
Weight: 53 lbs.