Hum Noise from Plug or Wire Area ? ?

Recently my speakers are giving this hum noise if amp and preamp are plug in where the interconnects and wires run behind my system. If I plug the amp or preamp in a different outlet the noise if gone of at least down to a "wisper". I know its not the speakers, I just can not figure what to do. I have everything plugged into a "Inland" power bar, if I plug directly to the wall plug in that area i get the hum noise.
Any suggestions as to whats going on ? ?
Could be an induced hum from power and i/cs or speaker cables running parallel and in close contact, or could be ground loop. Try cheater plug at in-wall outlet; if noise goes away it was a ground loop. If not, then its the cabling layout which you will have to rearrange to eliminate parallel runs of ac and ic/speaker wires. If they must cross, try to do it at right angles.
Thanks for the reply and insight, What is a "cheater plug at in-wall outlet ? ? How do I creat this confriguration ? ?

I have a cheater plug ! !
I used the cheater plug and the hum has stopped! I have my power box pluged with it, and a monoblock on the same outlet pluged in with a cheater, no hum. Must be the ground loop issue.
Post removed 
Just when I thought life had gotten a little simple . . .
Thanks for the added advise . . . I will get on it.

Bob_reynold, you mentioned Jensen Transformer. When I visit the website I m a little bit confused which model will solve the ground loop problem. Yr input is appreciatefd tq