Dhpeck 12-24-2017By any chance have you at any time had the sub connected at speaker level?
6. I just unplugged my Sub now as the rca cables are a bit bent up; however it didn't affect play for 2 hours yesterday without shutting off.
If so, the speaker level connection could easily account for the intermittent protective shutdowns, and possibly even damage. As you've probably seen stated in the manual the amp has balanced outputs, meaning that there is a full amplitude signal on the negative as well as the positive output terminals. If only one sub is being used, connecting most subs at speaker level would cause the signals on the two negative output terminals of the amp to be shorted together, and would also probably connect them to AC safety ground via some low impedance. As you may have seen, the manual specifically cautions against doing that.
Good luck. Regards,
-- Al