I bi-amp my Maggies with 2 rebuilt Hafler amps now. You'll find that there are two schools of thought on how to bi-amp:
Vertical: Here you use one stereo amp to drive the low and high side of one speaker. One amp per channel, so to speak. This is the way I do it with the Maggies. One channel to the woofer and the other channel to the tweeter.
Horizontal: Here you use one stereo amp to drive one woofer on each left/right speaker. The other stereo amp is then used to drive the tweeters. I've tried this but prefer the Vertical wiring approach.
You might want to visit the Vandersteen web site as I recall he used to have a much more detailed discussion on his recommendations with his speakers, which I used to have.
Hope that helps.