Lets break it down how well designed, multi-channel amp with a single power supply differs from a well designed, multi-channel amp with multiple power supplies differ when "bi-amping".
An amp with a single PS can provide X number Watts into any one channel, but divides those Watts between all available channels when more than one is active. If your goal is to put more power into a speaker, it isn't going to happen. You get X/2 Watts at most to each channel when driving two outputs at the same time (so X/2*2 or X).
An amp with multiple PSes can provide X/C Watts into each of it's channels, where X*C is the max it can pull from the outlet. If you bi-amp in this case, you can get X*2 Watts into the speaker.
If you're comparing something like the Axioms A1400-8 and Outlaw's 7700, the numbers work out like this:
A1400-8 driving one channel at max, it's getting 1400 Watts.
A1400-8 driving two channels at max, they're each getting 700 Watts for 1400 Watts total.
A1400-8 driving seven channels at max, they're each getting 200 Watts for 1400 Watts total.
7700 driving one channel at max, it's getting 200 Watts.
7700 driving two channels at max, they're each getting 200 Watts for 400 Watts total.
7700 driving seven channels at max, they're each getting 200 Watts for 1400 Watts total.
Is that making sense?
