Speaker Hum


I have a very loud hum emitting from my speakers when only my power amp is on, however with the preamp switched on the hum reduces greatly although still audible. Any suggestions as to why the problem exists and possible solutions would be greatly appreciated.
My system:
Adcom GFA555
BK Pro5 Preamp
Sony X111ES
Nakamichi CR2A
Parasound DQ 1600
Klipsch Forte
Audioquest Topaz interconnects
Saxton 12 GA. copper stranded speaker wire
yabob
If a T.V. cable is hooked up to your system, disconnect it and see if it helps...
See this other post, it will likely help you:

http://audiogo5.iserver.net/cgi-bin/fr.pl?aamps&1002308307&read&keyw&zzspeaker%20hum
I'd like to thank all who responded to my speaker hum problem. The person who suggested removing the TV cable from my system solved my dilemma.
Thanks again!!
Yabob: There is a device, some sort of isolation transformer, that you can plug your cable T.V. into, which will cure the problem (contact www.audioconsultants.com). Also, using balanced preamp/main amp will work. The cable T.V. folks should take responsibility for this -don't you think?
In that listening to movies through my system is not a priority, I've opted to remove the cables. Thanks for offering another solution.