Something's wrong with my subwoofer. I've only just bought it and I've told Richer Sounds where I got it, that I think its faulty. Half volume is a joke, and this is a 175 watt sub! I was told by someone who's got a much quieter sub that at half volume the floor moves. Even at full volume nothing much happens to mine and it certainly doesn't drown out any other sounds. Can anyone suggest what could be the problem.