NHT SW2P not enough?

Having a problem with my NHT sub . . . . for soundtracks and music, it sounds fine -- tight, solid, plenty of oomph. But when it comes to HT transients, like explosions, the impact just isn't there. I've played around some with positioning, but not a lot. I do have a pretty large room, and the SW2P is only a 10" driver with an 80 watt amp.

Do I need a) a sub with more power, b) a sub with better extension, or c) a lesson in subwoofer placement?

Any help appreciated!