what exactly is bi-amping and what are the benefits?
I look at it this way:
Say you have a speaker with 3 drivers, a tweeter, a midrange and a woofer. Each of those drivers has a frequency range, and each range is a curve, not like a square wave.
The goal is to end up with a flat overall frequency response, including when the frequency falls in the transition, (curve), between two drivers. In these transition frequencies, 2 drivers are contributing to the sound. The goal of a crossover is to blend those two contributions such that the result is a seamless, continuous, flat overall response. This crossover design is part voodoo, part science and all critical.
When you hook up a speaker normally, with two wires, the amount of power sent to each driver, at each frequency, is managed by the crossovers... transparent to you.
Active bi or tri amping means you have an external amp for each driver, and run a pair of speaker wires from each driver to an amp. Now there is no crossover in the speaker. YOU control how much power goes to each driver by controlling its amp.
You could do kind of a hybrid setup w/ one amp for the woofer, and the mid and tweeter sharing a separate amp managed with an internal crossover.
Passive bi or tri amping means you simply send the same signal, from the same amp, separately to each driver. I think almost everyone agrees there is little benefit here.
My thoughts: Even if I had the money and enthusiasm to build a home theater with active bi or tri amping, I do not believe my ability to manage the crossovers between drivers is as good as the best professionals. Industry leading crossover designers are highly regarded, and their products are considered best of breed.
If I had the interest, it might be an interesting hobby to explore. But barring some years of education and experience, I'll stick w/ the industry icons and simply plug-n-play.
If I over-simplified, or misstated something here, I'll ask one of the more technical experts to correct me. Thanks.