Or - as in my case - to drive the treble and bass sections of the passive speakers (L/R/C) independently as the received wisdom is that this makes a significant sonic improvement.
Such "received wisdom" is not universally accepted. If the single amp has adequate performance and power, using two will only offer a marginal increase in power and, imho, little else.
I had considered active crossovers, as then the connections may be less of an issue - dependant upon the crossover connections, of course. However, the speaker designer was quite firm that the greatest improvement would come from bi-amping and that the (passive) crossover was extremely carefully designed and would not be matched by active replacement. (He considered Y cable perfectly acceptable).
Well, he would.
OTOH, he is probably right in saying that "the (passive) crossover was extremely carefully designed and would not be matched by active replacement." No off-the-shelf active crossover will do as well.
Kal