Except you're forgetting what happens in the speaker with the passive crossover network. When one amp is driving the full "system" inside the speaker all frequency ranges are going to some driver with an impedance with allows for easy current flow. But when you remove the straps; you separate the system into a high-frequency range with a high-pass filter, and a low-frequency range with a low-pass filter. The other half of those ranges basically end up seeing a very high impedance, and turning the amp's energy to heat.
So when driving the speaker system 100 Watts, across the range, drives some part of the speaker's full system. When bi-amping, 100 Watts drives the highs, and 100 Watts, drives the lows. You're still only getting 100 Watts to any part of the speaker.
If you were to use the pre-outs on a receiver, input them into an active crossover network, remove the crossovers components from the inside of the speaker (make sure your active network matches the passive parts in point and slope), then get separate amps, with fine grained gain control, along with a precise audio spectrum analyzer to balance the gain of each amp against the driver it is feeding for a flat response. You might get some benefit from bi-amping.
The bi-amping built into receivers, feeding a passive crossover network, is an entirely marketing based feature; one manufacturer offered it, so they all have to offer it.
EDIT: Oh, I forgot to add. In the presented scenario, with one PS providing power to multiple channels, when bi-amping, you're more likely to exhaust all that's available because you have two channels with exactly the same content being driven to the same levels, but half of it being used to make heat instead of sound. The way multi-channels amps get away with higher single channel ratings, is that in the real world it isn't common for more than a stereo pair of channels to be driven hard at one time in anything other than test signals. But with bi-amping you quickly run into cases with 4 channels being driven hard.
Last edited by ClubNeon; 02/22/10 09:09 PM.
