Review: Sierra Audio Denali Amplifier

Category: Amplifiers

I believe there are several audio components that exist in the marketplace that never receive the lauds of the audio press, and deserve such praise. The Sierra Audio Denali is one of these products. Because of the demise of the high-end audio dealer in many markets, many of us rely on the audio press to set the standards that we use to purchase high-end equipment. This is complicated by the very limited distribution of many high-end products. These facts make it impossible to hear all the choices when we are ready to purchase. Products that truly raise the level of high-end audio simply don’t appear as often as we are led to believe. The Sierra Audio Denali is one of these products.

I was lucky enough to have the opportunity to audition one at home. And this may not even had taken place, for as a seasoned audiophile I have heard it all before. Besides, at the time I was bi-amping with two Conrad Johnson Premier 11A amplifiers, and I was both happy with the sound and secure with my place in the high-end audio world. I begrudgingly opened the wooden carton and began to set-up the Denali. In my 30+ years as an audiophile, I was not prepared for the sound I was about to experience – not from an amplifier. Revolutionary might be the one way to describe the Denali. Improvements in inner detail, openness, transient speed, and an overall sense of realism the scope of which are unexpected from an amplifier change. There were background instruments that were previously missing without the Denali in place. The members of our audiophile club were equally impressed. I was also not prepared to buy a single new amplifier at a retail of $6995. The Denali was so overwhelming that the price quickly became unimportant. Since I ended up with two, I assure you I am not kidding. One other member of our group actually secured a loan for one. Does it sound like tubes or transistors? Neither. It treats the music with the delicacy of a 20-watt tube amp, yet can quickly react with the authority of high-powered monoblocks – in either configuration (mono/stereo). Certainly one of its strong points lies in the ability to reproduce transient speed and attack with realism. Drums are reproduced with more authority and speed than any amplifier I have ever heard. Although I don’t limit my listening to contemporary jazz, I find that this attribute is critically important to the enjoyment of this type of music. Detail, top to bottom is outstanding, and inner detail is produced with resolution that is unexpected from an amplifier. Midrange and voice reproduction are pure and involving. The upper octaves are very detailed and never bright. There are a couple sections on Bob Thompson’s –The Magic in Your Heart CD where Bob “hits” the upper piano keys with authority. At realistic levels, the pianos upper octaves could be described as hard or bright when played aggressively. In this outstanding recording, this holds true and the Denali reproduces the effect accurately. This may be one of those few products that do become invisible in the audio chain. It’s soundstage is deep and wide, yet not overly so. I do find that the soundstage width does change according to the recording, which is what I expect out of any accurate amp or preamp. The real oddity is that this is a monoblock design that sounds incredible in stereo mode (which is what I initially reviewed). The use of two in monoblock configuration only enhances all of its attributes.

The partial reason for this amplifier’s outstanding performance lies in its excessively large power supply. They are certainly not the only company that believes in the advantages of large power supplies, however these may be the largest custom-made torridal transformers in existence. The capacitors are so large that if the Denali was equipped with the standard on/off switch, the draw would trip a 20-amp breaker upon turn-on. At 165 watts /channel in stereo, and 600 watts /channel in mono, the available current makes these figures insignificant. I believe there may be no speakers this amp could not drive to realistic levels. In my listening room, I have auditioned these amps (both in single and monoblock configuration) with three models of it’s sister-company Montana speakers, Revel Salons and Studios, and the Magnepan 3.6R’s. I was surprised that the Maggies played very loud with one amp in a 12’ x 16’ room with ten-foot ceiling. The Denali was nowhere close to clipping, and still had tremendous authority as though there was 3 times the power in reserve.

Bound for Sound’s Martin DeWulf, the only person to do a printed review of the Denali, said that “The Denali is yet another Benchmark product, one worthy of all the praise I’m about to heap upon it.” I agree wholeheartedly.

Tom Roberts

Associated gear
Over the year in which I have owned these amps, the following equipment has been used for a minimum of 1-3 months each.
Preamps:
Conrad Johnson Premier 17LS
Hovland HP100
BAT 51se
Sierra Audio K2
Mark Levinson Reference 32
Source:
Musical Fidelity NuVista 3D
Musical Fidelity TriVista SACD
Marantz SA1 SACD
Cables:
Kimber Select KS1030, KS1130, KS 3033
Speakers:
Montana EPS
Montana XP
Revel Salons
Revel Studios
Revel F30
Magnepan 3.6R
Amplifiers:
Museatex Melior
Conrad Johnson Premier 11A
Bryston 4BST


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