I've recently added a CHT-15 to my modest setup courtesy of Uncle Eric, I'm now looking to improve the bass response further. Having played around with the positioning of the sub, I'm left with a couple of sizable peaks in the frequency response (can't remember frequencies off-hand), and one major dip (110Hz). The peaks being up to 15Db above "average". Moving the sub around in the limited positions I can place it makes only a minor difference (3Db max) so I'm fairly certain it's the room in general causing the problems and not a daft location. Without going into full-scale redecoration and/or rebuilding, I'm looking at adding a Behringer Feedback Destroyer or similar to tame the peaks and hopefully boost the dip. By crossing-over the speakers at 120Hz instead of the current 90Hz, I can in theory maximise the use of the BFD over a wider frequency range. Am I heading along the right lines or barking up completely the wrong tree here? FWIW the sub is currently sat directly on the floor (no feet or spikes, onto carpet over wood floor above a cellar), near a room corner, facing down the length of the room into the side of a sofa. Rotating it 45 or 90 degrees only makes a minor difference and still leaves the two peaks and one dip.