[eugovector]

What devices are connected to the stereo. I have a ground loop in my cable connection at one apartment. Try disconnecting the co-ax cable, if you have one, and see if it goes away.

 

[eugovector]

Had the same problem. Surge protector wouldn't help because it wasn't a problem with the electricity, it's an improperly grounded cable connection to your house that causes a ground loop.

Drove me nuts, and I solved it by getting rid of cable TV