Subwoofer Hum

A friend of mine has the same Martin Logan Dynamo 700 subwoofer that I do.  His has had a hum issue for quite a while and he finally sent it home with me yesterday so that I could mess around with it.  I plugged it into the outlet and turned it on, no hum.  I connected the cable from my subwoofer to it, no hum.  I turned the volume up all the way and shook the house for a bit and it seems to function perfectly.

The only thing that I can think of is that his super cheap "linguine" cable was causing the issue, but didn't want to go spend the time or effort to hook his cable to my home theater receiver, so I just passed it back with a loaner BJC LC-1 cable that's the same kind that I'm using.  If that doesn't work, then I'm thinking that it has to be something unique to his house/setup.

Is it possible for a subwoofer cable to be so pathetic that a hum can be created from proximity with its own power cable?