I would second Wid's comment. If you isolate the cause, you may not need anything else. I think that Alan has an article on this website, somewhere, on ground loop isolation.

One of the most probable causes is from the cable TV line. Try disconnecting it and see if the hum goes away.

The Rat. M80s, VP-150, QS8s, SVS PC 20-39+, OPPO, Onkyo 703s, Harmony 880 Sony 60" SXRD HDTV