[maxxx]

I have an old Xtant 603x and it is behaving badly. There is something seriously wrong as I can hear the music (well, not really, just a distorted version of the sound) coming from the amp itself (without speakers)! What the heck is going on? I would think something is shorting/diverting the signal/output into the board? Grateful for input from those with knowledge on this type of stuff. Never heard this bizarre scenario in my life. TIA!

 

[Mooble]

The only possible explanation is what you described. It must be shorting somewhere and you're hearing little arcs of current that correspond to the music. You should probably be able to see the culprit if you open the case.