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 ? ?
Thanks