Owner went away for 2 weeks, left the amp plugged in and in standby.
Nothing else in the house was affected, but still could be a power surge
while away , I suppose.
Returned to find the functions and display work but no audio, or even
hiss on any output. No Pre-PA link that could be missing, no PROTECT
mode in the display and not stuck in MUTE. The SM is out there, but I
suspect something very silly, rather than pulling this all bells and
whistles m/c apart. Not switch mode ps, heavy lump. No relay click over
heard and the fuse/s not located yet.