Not meaning to hijack your thread.
Oddly enough, my BFD just developed a hum/buzz last night. Now granted, I had switched outlets during the course of moving the sub, receiver and PC but this is a physical vibration that is eminating from the unit. Previously it was barely audible when you had your ear up to it, now you can feel it vibrate when you touch it. This has translated to a horrendeous loud hum when the mains are being used.
Cheater plug solved the hum through the speakers, but the unit continues to hum merrily along...