Go back to the most basic setup and start from there. Just the receiver, speakers and sub, with both receiver and sub plugged into the same AC outlet and nothing but a wire antenna or CD/DVD player hooked into the receiver, again on the same outlet. Should be no hum. Add stuff from there and see when the hum starts.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8