K, that sub should be at least acceptable. On the setup, you should have the cable in the single sub input, which bypasses the internal sub crossover and gets it out of the way of the 325 crossover, which should be at 80Hz. The best placement, except possibly in a square room, is generally in the tightest corner behind an M22. Often a "boomy" sub is simply one that's set too loud. The idea is that the sub shouldn't attract attention to itself as a separate source, but rather that it gives the impression that it isn't working but the M22s are putting out more bass.
