An update.
Did yet another visual verification of wire connections, then plugged in and tested for DC at outputs: -4mV on one channel, +1mV on the other.
Still no front power switch, leaving rear IEC switch on, switching using external power strip. Refreshingly quiet power up and down with barely a perceptible click out of 96dB/Wm speakers.
Kind of agree with the routing comments, but not critical, IME. Twisted up the AC lines some. Left the DC lines, as there really isn't enough length to do much else with. Anyway, cored coils, especially closed-cores, don't have nearly as much stray field as air-core ones.
With no input, super quiet with ear right in front of efficient speakers. Sound is great, just a slight bit "etched," maybe, in comparison to past amps, but also apparently clearer. Bass somewhat drier, not necessarily better. Sighted, so utterly suspect impressions. But also speakON vs. problematic binding posts. Kinda wonder what REW says, and if the SHD/Dirac Live will actually call for retuning. Thinking damping factor here, and possibly the HF response March Audio mentioned, though differences, if any, seem lower in frequency.
Chassis barely warmer than room after many minutes of loud playing, which admittedly might've been a mere watt or two, average.
All in all, clearly the best amp I've ever had, and one of the easiest, cleanest DIYs ever. Highly recommended: Purifi Eval1 with Hypex SMPS1200A400 in pre-milled Modushop 230x280mm chassis with Schurter IEC input module and Neutrik speakON jacks.