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
try plugging all the equipment into the same wall outlet. If necessary purchase a outlet strip. Sounds like you have a ground loop. You can also try reversing the polarity of the plug.
It sounds to me like you have a ground loop. try using a cheater plug which turns the three prong power cord into 2 prong at the wall end to remove the Ground pin. you can buy one at radio shack for a couple of bucks. give that a shot and if it works, go ahead and pull the ground pin out of your power cord or continue using the cheater.you might have to experiment with the cheater on your other componets to find out exactly where the ground is comming from. if that doesnt do it some amplifiers have balanced inputs that need to be shorted usually between pin 1 and 3 (only )if RCA inputs are being used. if that is the case make sure you have the Jumper shorting pins inserted in the correct place.I would advise you to contact Adcom on that. if you dont have balanced inputs dont worry about it.
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:

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.