I remember seeing a thread here a while back about people putting concrete slab pieces under their sub to tighten up the bass, but I can't find it by searching. Lately, I find myself pretty satisfied with the major components of my home theater, so I'm now doing minor tweaks to eke out the last bit of performance possible. Last week, it was backlighting my TV (which worked out quite well), and this week that slab thing popped to mind. So does anyone have any suggestions on whether I should bother doing this, or any personal experience with this? My sub is a Polk PSW-350, which is forward-firing, so I wasn't sure if the slab would help much. The only reason I thought of this was that the floor in my HT is carpet over slab (no basement, ground level), and I wasn't sure how much I have to worry about coupling the sub to the floor. Of course, this could all just be masturbatory, but I'm always looking for ways to make cheap equipment sound expensive. I would appreciate any suggestions, comments, tales of personal woe, etc.