Review: Sierra Audio K2 Preamplifier

Category: Preamps

In my quest for the perfect preamp, I not only spent too much money, but the end result left me surprised. I say this because the preamp that I now call reference is far from my original choice. More surprising is the fact that I feel that this same companies amplifiers may be the some of the best ever designed. So why did I end up with the Sierra Audio K2? And why didn’t I consider it first?

First let me say that I am not one that believes in “one brand fits all” or that ANY company does all things right. Over the years, I have matched Conrad Johnson tube preamps with many other brand solid state amplifiers with the results I was looking for. As a general rule, I always have preferred the sound of tube preamps in combination with transistor amps. Specifically, I never felt the Conrad solid-state amps were quite state of the art. In other words, I have never been brand loyal especially at the sake of performance.

To give you an idea of my musical tastes, I find contemporary jazz to be my staple. I do enjoy full orchestra classical, big band, and most vocal pop/jazz. I also enjoy classical rock leaning towards the Doobie Brothers, Guess Who, Etc. Recordings that I commonly use for reference include Keb Mo – The Door SACD, Bob Thompson – The Magic in your Heart CD, and Pat Coil – Steps Ahead Sheffield CD, to name a few. I sold my audiophile vinyl collection last year.

I started this search upon changing my reference amplifiers to Sierra Denali monoblocks.
At the time, I owned the Conrad Johnson Premier 17LS, a fine preamp. The Denali’s set such a high standard that I felt a preamp change was necessary. I say that I spent too much money because in order to live with 5 different preamps in my home over a one year period takes quite a monetary commitment (unless you are a professional reviewer). Thank god for Audiogon, for this process is substantially less when buying high quality used components, which is what I did.

My first change was to the beautiful Hovland preamp. Not only the most beautiful preamp made, but also one of the finest sonically. Next was a 2-month preview of the Balanced Audio BAT 51se. Maybe the best build quality of the preamps I tried. Intrigued by the Mark Levinson Reference 32 after hearing it in many situations, I bought one for a another two months. In an effort to keep this short, I can not specifically cover all of these preamps in one review. I will discuss some of my observations as I describe the Sierra K2.

Because of the explanation above, I begrudgingly tried a Sierra K2. After all, I was not finding the ultimate sound I was searching for with the other preamps. I can say that the Hovland was very close to what I consider optimal. The night I initially hooked up the Sierra, I quickly listened to the Levinson Reference 32 for a starting reference. I expected the Sierra to be very dead in comparison since it needs to remain on for three days to sound correct. The opposite was in fact a large surprise. In comparison the 32 was slow, and compressed in the upper octaves. Three days later, the differences were more pronounced. My object is not to degrade any of these preamps, just simply report the differences that eventually led to my final decision. As they say, to each his own. In support of the 32 - it does have a positively magical quality in the midrange, which is hard to describe. It is also very musical, but the K2 betters it in tonal balance, detail, and speed. The BAT had the largest soundstage of the bunch as well as the signature tube sound. It did have some advantages of solid state design in that it was quiet, and fast. Again though, the K2 bettered it in resolution and musicality. As with the Sierra amplifiers, the attributes of the K2 are very close to the same. Closer than any amp/preamp combination that I have ever come across. You would expect this coming from the same designers, but seldom have I heard a preamp mimic the sound of its sister component. Could this be because the two are equally transparent? Am I experiencing more of the same where the recordings are concerned? Possibly. I can tell you that not since my original system of Bi-amped Magneplanar Tympani 1Ds, Audio Research SP6C, Audio Research EC21 tube crossover, and two Audio Research D52Bs have I been as pleased with the overall musical presentation. Not that the AR/Maggie system was better, but it left me not searching for more, which is where I am at now.

What more can you ask from the audio experience? The Sierra K2 has helped me get there.

Tom Roberts

Associated gear
Conrad Johnson Premier 17LS
Hovland HP100
BAT 51se
Sierra Audio K2
Mark Levinson Reference 32
Musical Fidelity NuVista 3D
Musical Fidelity TriVista SACD
Marantz SA1 SACD
Kimber Select KS1030, KS1130, KS 3033
Montana EPS
Montana XP
Revel Salons
Revel Studios
Revel F30
Magnepan 3.6R
Museatex Melior
Conrad Johnson Premier 11A
Bryston 4BST
Monster Power AVS2000
Tice A/V Elite