I bi-amped Paradigm Studio 20's off the 3805 last night. It was fairly easy. The high frequencies are powered by the the Front Left and Right, the low frequencies are powered by Zone 3 L&R. You have to run interconnects from the L&R pre-out into VDM In and set the VDM as the source input for Zone 3. Audioholics.com has step by step procedures on ther website.
The sound was slightly different from the bi-wire set up. Fortunately, I did not encounter the noise issue that can occur from this setup. Maybe it's due the four conductor, spiral pattern of the Canare 4S speaker wire.
Since the 20's have only broke in for a week, I'm not sure I can critically evaluate the difference at this time, but I think I prefer the sound of bi-wire vs. bi-amp- for now. Plus when you bi-amp, you can't use the auto set-up for the speaker calibration. I went back to bi-wire.