It's rather creepy and scary, but sometimes when I touch the subwoofer cable (MIT Terminator 5 Subwoofer) the sub turns itself on (if it's not already) and produces a hummm similar to the one you get when you touch the stylus of a phono cartridge. It happens if the receiver is on or off. And recently I touched the metal top of my Yammaha receiver, to wipe some minor dust, and the hum started, didn't stop until I turned off the receiver. Is it the cable? Until recently it only happens if I touch the sub's cable at the receiver's RCA plug end. Help, please.