Avguygeorge ........I'll confess too...I have tried it. I bi-amped using 4 identical monoblocks....all I did was split the signal from the cd player to the two separate preamps via a y-connector.......I only did it for a couple of hours just to see if it was possible. I used a Carver tube preamp on top and an Audio Research LS 10 solid state preamp on the bottom. I didn't take the time to do any serious listening, because at the time, it seemed like more trouble than it was worth to keep it connected like that. It wasn't all that hard to get the volume controls in synch....it wasn't perfect, I was just fooling around......I think Ben Franklin and Alexander Graham Bell made some important discoveries fooling around trying out new stuff. I'm sure a two preamp system could have its merits if someone took the time to work out the kinks.
Kr4 mentioned that there are still a lot of bi-amping skeptics.....bi-amping made my system more enjoyable five-fold....and I'm sure some tried bi-amping it and it just wasn't worth the trouble. Shoot, I've heard of tri-amping but never have seen it. Different strokes for different folks.
Just the thought of a discrete amp and preamp for every section of your speakers seems spine tingling if someone could pull it off.