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On the subject of +/-60V rail voltages for their custom operational amplifiers run in class A, Sound Performance Labs makes an interesting statement for their new headphone amp: "Almost without exception, present-day headphone amplifiers employ comparatively undemanding ICs. In the best cases they might work with symmetrical voltages of +/-15V to +/-18V and in less favorable cases, with only a simple supply of 9 or 12V from cheaper external 'wall-wart' power supplies. But the voltage level acts in circuitry much like the cubic-inch capacity to the productive power of a combustion engine: Cubic-inch capacity is replaceable with nothing but more cubic-inch capacity - and in the productive power of electronics, voltage level functions similarly."
Extreme cases of rail voltage lust are to be found in high-power SETs where 845s or 211s may see 1200V. For preamp purposes however, Esoteric's +/-38V do seem quite overdimensioned especially considering that gain is via ICs only. Equally overbuilt is the case work whose outer cladding is unusually massive, from the thick steel base to the solid machined cheeks, contoured fascia plus substantial top plate. That one, to eliminate fasteners on top, is fitted with four slip catches. Those securely lock into latches on the face and center divider such that you could pick up the entire machine from the cover's rear edge without securing the three bolts to the rear panel. It's not before you unbolt the sides, top and bottom that you fully appreciate just how persnickety strategic this box-in-a-box concept has been conceived, executed and then hidden from view.

The following two closeups show the flying leads connecting input/output boards and further evidence of advanced bent and punched metal work.

Volume encoder and input selector next.

For the A-100, closeups of the small-signal tubes and a pair of Czech JJ KT88 output tubes.

Esoteric's build quality has always been quasi legendary but the puzzle-like complexity whereby the C-03 and A-100 have been assembled seems more advanced still. This includes floating circuit boards in the preamp which are mounted with a bit of play on their stand-offs, presumably for resonance control purposes. In short, the upscale pricing here most assuredly buys you pride of ownership and a very high level of fit and finish - outside and in. Luxury is as luxury does? Whatever that really means, yes. Absolutely. And to convey an impression of how hulking the A-100's sheer physicality is, consider that it doesn't clear the tallest shelf of my Grand Prix Audio Monaco stand.

Once peeled out of its stout triple-boxed transit container, the A-100 deserves a very butch dedicated amp stand. For a mid-power push-pull valve amp, it's a beast. Just how civilized and cultured of a beast -- as in, refined enough to suggest more single-ended than phase-splitting operation -- we shall discover soon enough and over a variety of speaker loads...