Re-assigning channels for bi-amping
Yeah, the VSX-82TXS set up menus allow you to re-assign the unused 6th and 7th channels to bi-amp your front left and right mains. It's very easy. Took more time to run the cable than to re-assign the channels. It does NOT try to run the surround channels through fronts (contrary to the one concern posted above). Just be sure to map the left to the left and the right to the right.
I believe it sends the full signal to the speaker and lets the speaker's internal crossover filter out the unnecessary bits. Something like that. Way too technical for me to understand.
Anyhow, I have the B&W DM603 S3s as well, and that's exactly what I did. Make sure you remove the jumpers from the speakers. The difference is spectacular, though. I can play two-channel material at very high levels and there's virtually no distortion or break-up in the music.
Surround material also rocks as the set-up really helps a lot of the detail come out.