"RWG" writes:

Thanks to everyone for the quick replies!

The cable TV might be a contributor, and I'll check it out. I really hadn't
thought of that.

I like the idea of the UPS if it will provide isolation, as it won't affect
the stereo (unless I plug that into it too), so I don't have to worry about
it softening the voltage regulation for the power amp. And I'm planning to
get one anyway, so it's the old 2-birds-one-stone thing.

UPS systems generally do not provide the ground isolation you need.

For now, I think the first thing I'll do is strap the PC and receiver cases
together.

Did it help ?

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at
http://www.epanorama.net/