Here is the prognosis on Thursday from H.K.:
Well, of course the unit wasn’t shutting down when I tested it. However, I let it run and took some idle current measurements and found cause for concern. Even just sitting there idling (no audio applied), 2 of the channels were experiencing thermal runaway and a third channel had an idle current that was fluctuating all over the place. Tracked it to some more problematic transistors. I’m going to replace all remaining KTC3200’s (35 total) with KSC1845, which is a more reliable part. Unit is already disassembled, parts should be here tomorrow.