I have read threads about ground loop issues, etc. However, this doesn't happen when I have a sub in the mix of things. Currently, I just have the M80's, and a VP 150 hooked up to my HK AVR, and when there is nothing playing, there is a high pitched hum coming from the speakers. Anyone know what I might try? Maybe removing the banana plugs (from Axiom) might help -- i.e. just going to bare wire?

Any other suggestions would be highly appreciated. Thanks in advance.