My Marantz 7300 with (105 watts per channel - 8 ohms) was too under-powered to handle my Polk RTi150s (especially when lots of bass was cranking out of the RTi150s). So I bought a separate amp (NAD 218THX -- stereo output, 225 watts with 280 dynamic power - 8 ohms). Right now, I have the RTi150s speakers wired exclusively to the NAD; however, I am wondering if I could get a more full, realistic sound by bi-amping the speakers (i.e., running the 150s mid-range and tweeter off of the Marantz and the woofers off of the NAD). What do you guys think? Is this a good idea? Is there any reason not to do this (i.e., will using two different brands/types of amplification create some kind of sound disharmony?).