Did you use a subsonic filter at all? Its usually a good thing to have on any setup, much less a crappy sub in a box tuned lower then the FS of the sub.
Oh, and if the sub didnt matter as much to the setup as the box, we'd be all using q-power subs //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif