Just got a new Velodyne SPL 1200 subwoofer. Installed it with my Denon 5700. At first it sounded great. Then a few days later when I turned on my system, the sub emitted a series of booms whenever a signal is sent to it. I checked all my connections, and everything seems OK. Spoke to Velodyne, and they said it sounds like a bad amp. Velodyne says they will ship me a new amp, and that it would be easy for me to install the new one. (This will be quicker than swapping sub for a new one as my dealer said it will be a few weeks until he can get his hands on a new unit). Before I take apart my sub, I was wondering if I may be missing something simple that causes my sub to act this way. Any ideas? Moreover, does anyone know if it is relatively simple to swap out the amps as Velodyne suggests?