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Because the A-03’s bass prowess is slightly shortened, I preferred it when associated with the C-03 preamplifier set to +12dB gain. This provided greater bass extension and weight as well as boosted dynamics. The 0dB setting of the C-03 provided crisper transients at the expense of bass and ultimate dynamic power. Your system and preferences will determine which gain setting works best and what type of preamplifier would best suit the A-03. And don’t forget that I am comparing the A-03 to a dynamic champion and that in absolute terms, the A-03 is neither slow nor heavy when properly matched up.


Association with the Wyred4Sound STP SE preamplifier was not as successful as with Esoteric’s own C-03. The W4S has a denser presentation overall than the C-03 and the match with the similarly dense and rich A-03 and my Zu Essence just veered into more darkness than I fully enjoy.


The W4S preamplifier complements my Genesis amplifier perfectly by bringing out the last level of tonal intensity that delights me but when it comes to the A-03, I found no better match than Esoteric’s C-03 preamplifier. They were designed together and they sound it too!True magic and system synergy did not fully click until I introduced the E-03 phono stage into the mix.


Just like throwing a pinch of fiery peppers into an otherwise flavorful but mild curry, if you listen to a C-03/A-03 system, ask to listen to vinyl though the E-03 as well. You won’t know exactly what the pair is capable of until they’re fronted by an E-03.


Starting with vinyl, Solti’s 1964 reading of Mahler’s First Symphony with the London Symphony is one of those classics I can’t seem to get enough of. With the A-03, the LSO spread wide and deep in front of me. Instrumental tonal colors were saturated with truly spectacular brass instruments resonating in a palpable hall. Those massive symphonic orchestras pose no challenge whatsoever to the A-03 which never lost composure no matter what instrumental mayhem was unleashed. Absolute unflappability! I thought the GR360 was excellent already but the A-03 provided even greater insight into the orchestral masses, always keeping them in check for size and position yet allowing a very organic fluidity to the music. Often you get control and precision with rigidity—or fluidity with fuzziness instead—and rarely have I heard an amplifier which combines both qualities as the A-03 does. 



Switching to Gregorio Paniagua’s Folia or Tarentule-Tarentelle, both transient fireworks, the A-03 again demonstrated superb tonal richness. Transients in the form of percussive impacts or string plucks however were not as sharp and precise as over the GR360. On these two discs my vote went to the American amp as better preserving the inner life of the music. Advancing to vocals with Mozart’s Magic Flute directed by Karl Boehm again showed the A-03’s superiority in the midrange. Dietrich Fisher Dieskau never sounded better as Papageno and I have yet to hear a more convincing "Ein Mädchen oder Weibchen" than DFK’s. His unique almost whitish voice seemed real through the A-03 and acquired a 3D presence right between the speakers. That said, the triangle’s upper harmonics sounded a little shortchanged compared to what I am used to. In a trade-off, I’d take DFK’s voice over triangle realism any time however. The GR360 was very close texturally but tonally the A-03 pulled ahead and also with a hint more realism although I am really nit-picking.


Switching to CD and SACD over Esoteric’s X03SE for another dose of brand synergy—and Esoteric’s Mexcel balanced interconnects for good measure—returned a very similar impression. On Mozart’s Symphonies 38 to 40 under Sir Charles Mackerras directing the Scottish Chamber Orchestra, both amplifiers came to a tie. The GR360 better mastered subtle dynamic flutters, the A-03 offered greater tonal richness. Both seemed equal in stage depth and width as well as imaging precision (both excellent on all other aspects I must add). The Genesis amplifier had greater weight and authority on the timpani, the A-03 greater lushness on the strings. Both presentations were superb and convincing in their own ways.



Moving to Händel’s Messiah as performed by the Dunedin Consort, the A-03 once again offered the most convincing presentation of voices and a slightly less agile rendition of strings and winds. Considering that this version of the Messiah errs towards a radically simplified orchestra, the added warmth and richness of the A-03 was a rather welcome asset. Yet again, the differences were a lot smaller than what I am making them out to be for the purpose of review distinctions.


What about less classical fare? As it turned out, any music that had either a strong dynamic or transient component to it was better served by the Genesis. That was unquestionably the case for any of Renaud Garcia Fons’ instrumental fiestas, ZZ Top’s "Tres Hombre", any of the Gorillaz’ albums or electronica like Jean-Michel Jarré’s "Revolution". When vocal finesse was required, I preferred the A-03 for all occasions, be it females like Diana Krall Live in Paris or males like Johnny Cash or Maxime LeForestier. The A-03 seemed to provide some of that lit-from-within quality tube SETs are famous for, not all of it but certainly a dose. The GR360 was never far behind but the A-03’s presentation of voices always sounded more enticing if perhaps not quite as neutral. I think the GR360 was more honest but the A-03 has a way with embellishing voices I plainly found addictive.

Most of my listening was done over the Zu Essence yet at the end of the review period I switched to the FJ OMs. With those, the A-03 proved to be the better amplifier, period. The FJ OMs’ focus is the midrange, with no deep bass and a not very extended treble. With the GR360 I always sense a hint of edge and stiffness whereas the A-03 offered tremendous fluidity that magnified the qualities of the FJs instead of short-changing them or highlighting their weaknesses. Vocals through this combination were as involving and life-like as I’ve ever heard at my house.


Actually, the A-03 and C-03 on the FJs reminded me of my tubed McIntosh MA2275 in many ways, albeit with better control, greater overall transparency and certainly greater tonal beauty but also slightly shorter treble extension. The FJs are not very difficult to drive, leveling the playing field between MA2275 and Esoteric combo but I suspect that with more challenging loads, the A-03 would keep going while the McIntosh would soon give up (I know it does from experience with the current-hungry Nomad Audio RPDs). Unfortunately I do not stock any power-mongering speakers to verify this assumption.

Encouraged by the winning combination of FJ OMs and A-03, I pulled my Rogers LS 3/5as out of the video system to again confirm the perfect synergy of the A-03 with midrange-centric speakers. It turned into one of the best auditions of the old British ladies I have done in a long time. The Rogers’ main weakness—besides low sensitivity and no bass to speak of—is a lower treble band that can turn dry and even harsh with the wrong amplifier as verified many times with the GR360, Musical Fidelity A5 and very painfully so with a Krell integrated. Over the A-03, the LS3/5as’ treble was as sweet as can be, matching what I have heard when pairing those speakers with the finest EL34-based amplifiers but again with far better control and transparency.



When it comes to associations, I’d imagine the A-03 will work fine with speakers that are open and agile, with sharp transients and in need of a good injection of tonal flavor. Esoteric’s own MG20 seem to fit the bill quite well, some Avantgarde Acoustic designs (which Esoteric happens to distribute in Japan) probably do too and I would bet that the Genesis G7.1f I reviewed a few month ago would simply blossom. Despite that, my successful experience with the FJ OMs and Rogers prove that the A-03 should certainly not be limited to speakers in need of mellowing or enrichment but be a top consideration for anybody (deep pockets permitting) who is chasing tonal richness, superb elegance, finesse and musical refinement in a package that does not include tubes. To push performance even farther in the direction of fluidity, rare elegance and transparency, the C-03 preamplifier almost seems mandatory, the association being so synergistic and clearly meant to be.


In the end I do prefer the GR360 and W4S association in my system by a very small margin because the Zu Essence thrives on extreme transient nimbleness while requiring no tonal reinforcement whatsoever. Had I owned a different pair of speakers, the endearing qualities of the A-03 would probably have won the day. If you are looking for the vaunted qualities of class A amplification implemented without any concession and pushed to the limit, check out the Esoteric A-03. It’s a real seducer.
Quality of packing: Simply one of the best in the industry.
Reusability of packing: Multiple times.
Ease of unpacking/repacking: No particular issue if you don’t mind moving an 80lb anchor.
Condition of component received: Flawless.
Completeness of delivery: No issue.
Quality of owner's manual: Simple but complete.
Website comments:  Complete and informative.
Warranty: 2 years extended to 3 years with returned warranty card.
Global distribution: See Esoteric website, available broadly.
Human interactions: Always responsive and helpful.
Pricing:  On the high side for 50 watts but these are class A watts capable of driving anything shy of the most challenging loads. Can be bridged to 200 watts for a pair of $24,000 monos, not unrealistic compared to the price of other statement amplifiers but obviously reserved to a small community of the lucky few.
Final comments & suggestions: Unlike other Esoteric components I have reviewed over the years, the A-03 is highly sensitive to tweaking (power cords, no power conditioner, vibration control) so be prepared to experiment to get the most from it.
Esoteric website