I respect the sentiment of you horn owners that dislike different amp topologies. And I expect, as Morricab mentions above, that to successfully multiamp (passive or active) it should be done with similar or same sounding amplifiers regardless if one uses tube or sand amps.
I'm going to try this on my Altec model 17s as I have never got them quite right with passive crossovers, and I have tried a few. I will build a First Watt active crossover and probably test this with a small 4x30w hypex class D (because I have one) or use my DIY First Watt class A amps (F6 and M2), that sound similar but not quite the same, or maybe build a second pair of Neurochrome Modulus-86s. My day to day Altec A5s seem to be more forgiving and sound fine with passive crossovers (although of course not the same with different crossovers). I have tried 3 different crossovers, and now prefer a Hiraga inspired crossover.
Just to correct a misunderstanding earlier in the thread, the Neurochrome Modulus-86 is a class AB amp, not class D. Inexpensive to build and quite good for its price