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I must admit that the visual effect of having the X03SE, C03, A-03 and E03 in my system for the past month was impressive. The $39,000 sticker for the set (including a pair of Esoteric Mexcel balanced interconnects) is steep but never seemed out of line when considering build quality, physical heft or their outstanding musical performance. The price begs for the “exclusive high-end” classification but so do build and sonic qualities of the full Esoteric Monty.

In use the A-03 differed from other Esoteric gear I reviewed previously in one significant way. Unlike the C-03, X-03SE, P-05/D-05 or E-03, it turned out to be quite sensitive to tweaking and set-up. My initial impression was underwhelming. The amplifier sounded heavy, transients lacked sharpness and definition and the overall sound felt asphyxiated. As I have since learned, that is absolutely not how it should sound.

The primary factor in the A-03’s transformation was finding the proper power cord. I began with two different Isotek cords and the A-03 just would not cotton to either, sounding opaque and anemic. Switching to the Zu Mother was a huge improvement as though a heavy weight had been lifted to let the amp regain its freedom. Yet there was still a little congestion in the midrange which completely vanished when switching to the Accustic Arts Ferrite II. A second improvement primarily in transient speed and clarity occurred when I inserted a quad of Isolpads under the feet of the amplifier. That could be redundant if you own a proper amplifier stand but since I don’t, the pads provided a significant improvement over resting the amplifier directly on the floor. It was only after weeks of operation that I discovered the final improvement which completely removed the slight dynamic restrain that had been bugging me for weeks.

While I was experimenting to address an annoying ground loop plaguing the E03 phono preamplifier—the solution was a cheater plug—I ended up removing all power conditioners from the system and putting them back in one by one while testing various connecting options. As I was focused on the ground loop in the phono preamp, I did not immediately notice the change but after an hour or so of listening to music, it hit me – the final shadow of dynamic reticence had lifted, the music rose and sunk with ease on huge swings and micro flutters alike. As I looked at the system, there was only one difference versus the initial setup. The A-03 was now plugged directly into the wall rather than into the Isotek Titan power conditioner. This past month I listened to the A-03 plugged directly into the wall with the Ferrite II cord and that’s how I consider the amplifier to give its very best.

If you have any preconceived ideas on how a class A amplifier should sound, don’t throw them away quite yet. The A-03 is a superb example of the breed. Just on the warm side of neutral, with a sweet and golden treble (this does imply that the treble won’t shimmer like the best), slightly foreshortened bass, superb transparency, ever so slightly rounded transients even when fully optimized and a midrange to die for that’s lit from within, sensual and enticing beyond belief.

Tonally magnificent and dense yet certainly not deserving the ‘dark’ qualification class A Mark-Levinson amplifiers of yore rightfully earned, the A-03 is as removed from cold and clinical as is possible without turning euphonic. It’s the absolute antithesis of the first generation NuForce amplifiers if you’re familiar with those.

Compared to my similarly priced Genesis GR360 with MDHR, a few things should be mentioned. The A-03 wins in tonal richness and midrange wetness without dispute while the GR360 shows its superiority in the bass, treble extension and neutrality. More relevant in my setup of above average efficiency speakers, the GR360 does wake up earlier than the A-03 when it comes to low levels (a possible limitation to watch for if listening with high-efficiency horns). There is a very clear point with the A-03 at which the musical scenery opens up and tonal colors blossom fully. The GR360 does not really have a clear take-off point when sound level and power requirements are decreased. At close to whisper levels, it retains its integrity a lot better than the A-03 (something that may be of little value to you but is critical to me as I do most my listening in the early hours of the day when the rest of the family is still asleep).

The GR360 also proved to be nimbler and capable of greater reflexes particularly on very minute dynamic fluctuations. When well matched, the Esoteric is neither heavy nor slow. The GR360 simply goes farther, probably due to the Maximum Dynamic Headroom Reservoir optimized to deliver the same dynamic response from the smallest fraction of the first watt to full output.