I was having the same problem a little while ago where my amp started humming. I tried multiple things without success but later I found that the problem was being caused by a potable heater connected somewhere else in the house.
if you ground is not isolated everything that is connected to the house is picked up by some of your components.
in my case that's all it took to get it fixed.
Hope this helps.
Adalberto
if you ground is not isolated everything that is connected to the house is picked up by some of your components.
in my case that's all it took to get it fixed.
Hope this helps.
Adalberto