Most of us have speakers with fairly high sensitivity. I am sure all if not most of us have been plagued by this at one time or another. I just saw a recent post about a problem and just spent over 2 hours trying to ring the last bit of hum out of my system the best I could. As usual just stumbling blind I found the right combination of grounds between my unbalanced, balanced, and cable TV feed. I don't want to tell how much time I have spent chassing the bugger down in the last 6 months. Why don't we pool our experience and try to put together a reference on the best aproaches that have worked for us.
Rob