I recently got a Rel Q200E as a first subwoofer, with an agreement with the shop to swap it for something else depending on how I get on. Sadly, I seem to have the dreaded hum problem, but in my case it hums even with only the mains cable connected. It's not connected to earth, and I have flipped the standard "ground" switch to no effect. Unlike the story here: http://www.avforums.com/forums/showthread.php?t=26601&highlight=subwoofer+hum it is still humming from the speaker cone itself whatever way I change the "ground" switch. If you feel the cone it is vibrating continuously. I've tried the power cable in various sockets, and it hums louder or softer but doesn't ever stop unless I remove the power cable. It hums the least connected to a belkin surge protector with mains filtering, but even that doesn't get rid of the hum entirely. I assume that my problem is that the ground switch is nonfunctional, since flipping the switch seemed to have no effect atall. Is this a case of returning the subwoofer, or am I missing something? Forum help greatly appreciated!