"rob" wrote in message
ups.com...
I had some really cheap speakers from a compact entertainment center on
my HK 520 receiver. There was a humm on the right speaker so I just
balanced everything to the left speaker. Now I purchased some new
Mission floorstanding speakers. Unfortunately, I still have the humm.
Here are the symptoms:

1) Humm is only on the right channel
2) Humm is only for analog input sources
3) There is no humm for optical input sources

Optical inputs are immune to grounding problems.

4) When disconnecting an input the right channel has huge humm whereas
the left side does not.

Does disconnecting the input cables cause the hum to be eliminated?

5) After switching the L/R cable, i.e. L out on R in/R out on L in, the
humm stays on right channel
6) Humm is also there when listening through the headphones

That is normal. the headphone jack is often hooked across the speaker
outputs with dropping resistors.

I would appreciate any input on what you think the problem might be and
if possible how it could be fixed.

Its probably a grounding problem - what's known as a ground loop.

Does removing the antenna cable have any effect?

What about disconnecting analog input sources, one at a time?