More powerful amp for top or bottom?

I'd be careful passively bi-amping with that much of a difference in output power. Bi-amping is a fussy business, usually best to stick with matching amps to ensure impedences etc. are closely matched. Presumably the 2 amps are from different manufactures which could cause problems.

You might find one or the other works better alone with good quality jumpers.

Meiwan...Can you please explain the types of problems that could arise from that great a difference of output power. Also the types of problems from using different amp manufacturers. I'll probably end up with a very similar situation so any advise is appreciated.

Bass definitely requires more power. However, it is almost impossible for both of these amps to increase in volume in a neartly exact fashion. Even if you find a good match at 10 watts, was volume increases one amp may increase at a different rate.

Strangely enough, when I was bi-amping Maggie 20.1's, sound was best with more power on treble and mids. Never would have expected that...

Tyler makes active speakers. Could you go that route. Give him a call