Getting rid of the receiver in favor of a pre/pro is going to give you leaps and bounds more dynamics for DD/DTS movies...if your receiver has those features.
Receivers are soft dynamically, even from the preamp section. Other than that, trying new amps and cableing is going to help. Also, SET THE PRE/PRO OR RECEIVER(which you have) TO "SMALL"!!! You should not be driving the maggies (or most any speaker) bellow 80hz. That should be dedicated to the powered active subwoofer, which does a much better job of handling dynamic bass info.
Good luck
