My new SVS 20-30PC has started to emit a loud, low thump or pop whenever I turn the receiver on/off, change the TV station or turn muting on/off ,etc. It plays OK, though, once the program comes on. Everything was fine till I moved the sub to another part of the room to see if I got better response. I didn't so I moved it back where it was. I turned off the power on receiver and sub before disconnecting cables, etc. I have everything hooked back up right, I think, with subwoofer cable plugged into one of the line-level inputs. I tried plugging the power cord into different sockets, with no improvement. With the sub turned off, this doesn't happen with the other speakers, so it's not the Denon 5700, unless it's just a problem with the LFE out. I tilted the sub some moving it but I didn't drop it. Also, as a result of the calibration efforts, my receiver's sub level is -8 and the SVS volume is only at 3, so I've reduced the volume significantly from before, so it's not too loud. Maybe it's too low powered now ?