One more thing is make sure the sub is calibrated..an efficient sub like that does'nt need much power. It can sound overbearing quite easily if its too loud.
I would say you either have a bad subwoofer placement or are crossing it too high..a bottom dweller like that should be crossed at 60Hz or less IMO and does not require corner loading.
The first thing I would do is move the sub to a different location and go from there.