Yo Avitar, Try this. Disconnect everything from your amp except the speakers and the power cord. Turn it on and listen for the hum. If you have the hum, then it is in the amp. If not connect the interconnects to the amp but not to the receiver. (Turn off the amp when ever you make connections.) The listen for the hum. If the hum is there, then it is being picked up by the Cardas cables. If no hum, connect the cables to the receiver. Check for hum without the receiver plugged in and no other components connected. Anyway I think you get the idea. Try plugging in all the source components one at a time till the hum shows up. The weird thing is that you should only hear a "hum" in the woofer...not the tweeter. If it is coming from the tweet, then it is probably transformer induced emi not a ground loop. I suspect your interconnects are not sheilded adequately.
Hum from new amp?
I just bought a used Belles 150A 3 channel amp to drive my B&W N805's HTM2 center. I noticed a very slight hum coming from the tweeter.It cannot be heard from more than 6" away from the tweeter. It is not affected by the volumn control. Right now I have the Belles amp sitting directly on top of the Marantz SR7000 which is being used as a pre-pro and to drive the rears. I am using double runs of VDH CS-122 for speaker wire and Cardas Quadlink IC's. The Amp came with what seemed to be a heavy power cord. Both the amp and receiver are plugged into a 6 plug power outlet with surge protection. Please make some suggestions to fix this problem. BTW the sound quality is greatly improved by the Belles amp. The soundfield is much wider and voice are more in front of the speakers. Separation is much better and things are bigger and wider sounding. Voices have more depth and emotion.