Eh, me thinks this has been discussed earlier in thread. And reached a dead end. But you are right real bi-amping requires high/low pass filters at the line level then feeding individual power amps to the low/high speaker elements, sans internal xover.When Bi-amping is used with passive crossovers it is really no different than Bi-wiring. The amps still pass the entire audio spectrum and are still just as prone to clipping.
It's really just that simple.