You have actually maybe found the problem. Your amp does not like the power it is supplied. You are talking about a mechanical hum right? If not, and it hums out your speakers, then try a cheater plug on your amp to remove the ground.
For mechanical hum, you could try one of those things that fix the power (not a conditioner). Products like the Powervar, Blue Circle Music Ring, Equitech, Furman, PS Audio Power Plant, etc.. Waring that sometimes these devices will solve your gear hum, but then hum themselves.
For mechanical hum, you could try one of those things that fix the power (not a conditioner). Products like the Powervar, Blue Circle Music Ring, Equitech, Furman, PS Audio Power Plant, etc.. Waring that sometimes these devices will solve your gear hum, but then hum themselves.