Hair dryers, kitchen appliances, dimmers,... can cause this even by using dedicated lines for your system. One easy way to check is heat produced from the transformer when idling or with no signal (check preamp also). Try to relocate and eliminate possible suspects as advised above or get a dc blocker, it works.
Can moving wire location at circuit breaker reduce hum?
The power line going into my music room will oftentimes make the amps’ transformers hum. I’ve tried many things but have had no luck. If I take any component that’s humming into a different room run on a different circuit breaker, the hum disappears.
Would swapping out the wires that go into the two separate rooms at the breaker make any difference? Or is it more likely that one of the outlets on the circuit that goes into my music room is somehow miswired and is causing the hum? I can unplug everything from the circuit except for my amp and it still hums.
Any suggestions on what I might be able to do short of hiring someone to run a dedicated line?
Thanks,
Mamoru