JohnK and Bridgeman:
Thanks for the responses. I have tried to isolate the ground loop issue and have determined that the cable is part of the problem but not entirely the culprit. By that I mean that when the cable is connected, the hum is very noticeable. When it's disconnected, the hum goes away for a short while then returns, although not as pronounced. I purchased an isolator for the cable connection, which solved the hum, but when I switch inputs or when the dvd player tray loads, a "thump" eminates from the sub. That's when I went with the in-line isolator for the sub. That took care of all noises. My only concern with that is I am afraid that I am robbing the sub of signal. I've since recalibrated the system and all seem to be performing fantastically. But you know how it is, there is always that nagging question "can it be better?".
After reading your replys, I think I have the best possible setup.
Thanks again!
