I was thinking - could it be the a problem with a receiver? I was just watching Superman Returns on DVD and the rumbling is there. Not the super, house rocking, windows rattling type of sound but the sub is worker hard. However, when people speak or when doors close, it sounds like there's something missing in the bottom-end. I recognize that as a problem the occured when I had the PSBs up front as well. I'm very temped to blame it on the AVR right now!