Hello,
I presume that you speaker's passive crossovers are outboard and totally removeable eg Magnepan 20.1, Analysis Audio Amphitytrons (both of which I do own).
In this case, active crossover infront of the 2 amps will provided 4 channels of amplification, one amp feeds one speaker.
This setup is far more superior than using 2 mono amps and passive crossovers, 2 mono amps are better than 1 stereo amps.
My current setup is like this:
1 pcs mono Spectron MIII MKII feeds the bass panel of 1 speaker, second mono feeds the bass panel of the other speaker and the third stereo MIII MKII feeds both speakers mid/treble panels.
My next move will be the use of 4 pcs MIII MKII all in mono mode to deliver 4 channels of power.
If you have not order your Spectrons as yet, I would to suggest the upgraded V-Caps and Bybees.
I also have tried these setups with Pass amps and active crossover conf has always been more superior sounding.
I have been using true balanced ICs and I cannot hear even a hiss with ear pressed against the ribbon tweeters in my system.
All of this I know because I have done them.
Terry