I think your sub would have to go too high to do it by biamping. Here's how I do my system(although someone might have a better way): I biamp my main speakers with an electronic X-over, and run a separate line out signal(which is full range) to my Velodyne sub. I turn the crossover on the sub to minimum (which is 40hz on my Velodyne)and then raise the volume on the sub until it sounds like I like it. Works for me, although there might be a bit of overlap on the bass, depending on how low your mains can go. Biamping is the only way to fly! If you need more info on my system, e-mail me and I'll give you particulars. Good luck.
