Hawk, make sure you check the settings, too. It's not just "how loud" but "how loud at what frequencies" that matters.
Murph or somebody else smart already alluded to running the speakers as "large" which you probably should NOT do. That is, have the crossover in the amp send all signals below 80Hz (or whatever you choose) from all channels to the subwoofer. If your receiver only has to push signals above that frequency AND your speakers only have to produce signals above that frequency, everybody will be a lot happier. So, noodle around in the settings on your receiver some.
