As long as you keep using your passive crossovers, then I'm afraid there is audibly not going to be any real-world justification for this change. None whatsoever IMHO. The reduction in bass frequencies are largely redundant here...and the only point at which they might audibly change anything will likely be at the point at which the crossover values are being altered, as Erik pointed out. The only real advantage with bi-amping with active crossovers AFA the amps are concerned is more that (if you're using boxed, dynamic speakers, that is) the bass frequencies from the enclosed woofers that are bouncing back through the cone and creating increased EMF are no longer as adversely affecting the higher frequencies as they do in a single amp.
But, even that advantage I'd say would pale in comparison to the advantages that replacing your passive crossovers at the same time you go active, would bring you - even if all you did was replicate original factory values throughout the crossover range...a much more coherent sound in terms of dynamics, tone and sound staging/imaging all the way through the crossover zone. So, if you were to consider replacing your passive crossovers with (fully) adjustable active ones, then that might be another matter...quite recommendable - IF you're both willing and able to take things that far...and there will be a learning curve for all that, as well. But, if otherwise, then I would certainly recommend against this move...just far more cost and complexity IMO than the miniscule amount of gain would be worth. Hope this helps.
