Don't waste your time with passive bi-amping or bi-wiring. The differences made by bi-wiring are nil, and passive bi-amping makes little or no difference in the sound.

The only real bi-amping scheme that makes a very audible difference is active bi-amping where the passive crossover network in your speaker is replaceced with a direct speaker driver-to-amplifier connection, and the frequency division is performed by an electronic crossover network before the amps. This route is very labor intensive to do correctly and the use must have the test equipment to properly set a system like this up. That is why it is not offered by manufacturers of consumer systems. It is routine in professional systems though, and all movie theater systems are actively bi-amped.