combining amp and receiver for HT

Hi, I probably spend more time on straight music (80%) to HT (20%). I have BW Nautilus 804's driven with a Classe 300 amp. I use a Harmon Kardon 500 as the pre-amp/receiver. When in HT surround mode, I use some BW 602s2 for the rear speakers and let the amp drive the fronts. This seems to work ok, but I don't really get much of a Kick out of HT. Of course I don't have a center or sub which may make all the difference. Question is, whats the best next tweak to "get the best of both worlds"?
thanks
joeb