I just recently installed a IB sub in my attic using 2 15" Dayton DVC IB drivers, PE 250 watt plate amp, and a Behringer Feedback Destroyer. Not to brag or anything, but this is the best bass I think I've ever heard. Very tight and accurate and can be very loud with little amplication. Seems effortless and enveloping. The BFD was mandatory with my room. When I first fired up the sub it sounded real bad as there was such a ragged freq response. Once I figured out how to use the BFD I was able to get a ruler flat response at 90db's from 18hz to 125hz using the RS meter with corrections. Can you say "No rolloff until 18hz"? I need to play with the equalizer more as a flat response doesn't necessarily sound the best. I also need to deal with a couple vibrating recessed lights in the ceiling. Here's the beauty part: The total cost of my system was around $500.00. The only thing necessary for aesthetics was the cover for the hole in the ceiling. No huge box or sonotubes in the corner.