OP- have you decided anything on the subwoofers? To answer your question, I fed the subs+mains a full range signal. I believe that my Denon AVR had them set to 40hz, IIRC. They sounded great! It gave me a really nice sence of depth and added "weight" to the sound on movies. I wish that I still had those subs but unfortunately they were not all mine and I had to give them back to my buddy that loaned them to me. Right now I am having Dave at Ascend Acoustics modify my Sierra-1's to now have a RAAL ribbon tweeter in place of the domes. I have been kicking around the idea of building some mid-bass enclosures to do the same configuration that I discussed earlier. I can't decide between a trio of JBL2225's (or 2226's), or possibly a trio of Dayton HO15's or Dayton DVC15's. Decisions decisions! I am also in the process of building some high effeciency mains, and just finished my DIY subs not even 3 weeks ago. I have been busy! LoL!