lonemountain
"Passive Bi-Amping
Passive bi-amping is what you typically see when bi-amping is discussed. It’s the most common. With Passive bi-amping, you are still using the crossover parts of your speaker to send the correct frequencies to each speaker driver."
this is for speakers whose crossover is designed to alternately accept bi-amp via a removable jumper, as the AR-2ax crossover is.
"Bi-Amping with an Active System
You can also bi-amp with an active system. This is not very common and only available with a limited number of brands. With an active system, you actually have a separate electronic crossover in front of your two or three amps. It gives each amp the correct set of frequencies and you remove the crossover from the speakers."