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