Russ, what you are describing is now more obvious to me.... you have/had a clear case of your subs overloading your room. What size is your room? Matching a sub to one's listening space is crucial, because with a mis-match the ability to overload the room becomes more likely. I would suggest removing your subs altogether, and attempting to see if you can place your Vivid's in a space that will lock them in as to the bass response. If you feel that once you have done that, that they are still lacking in the bass dept, ( although I happen to think Vivid's are VERY able in their ability to reproduce good clean bass); then I would investigate a much smaller sub than what you currently are using. Probably something using a single 10" driver...max. The RPG panel will help, to some extent with the bass bloat...but since you are overloading the room, I doubt they will ameliorate the problem entirely! Better solution is to carefully match the speakers ( and if necessary the subs as well) to your room size and dimensions, IMHO.
BTW, I am actually not a huge fan of DSP...beacause IF the room is getting overloaded by your sub/speaker at the lower volumes it will simply apply a band-aid and will not truly solve the problem. Far better to solve the speaker/sub/room interaction with the correct match of gear to room in the first place...again IMHO.
+1