The theory is that each amp can work on it's own slice of the bandwidth (frequency) rather than one amp trying to reproduce everything from 15Hz to 45k Hz (or whatever range your particular amp and input are)

So you'd have one amp focused specifically on tweeter range, and one on mids, and one on bass, each one has less workload. Or you could even have each amp designed specifically for that frequency...i.e. a bass amp might have bigger caps for those big impactful hits that need a surge of juice that tweeters would never need.

Add to that, the modern thing that is in vogue is having high end digital processing that highly tweaks both crossover and phase - so each amp not only gets *only* the frequency it needs, but everything comes out of the drivers time aligned for better cohesion of the overall output. Having everything done digitally *before* the amp is not only highly accurate, but you aren't losing watts, nor at the mercy of a crossover and all it's passive parts and their variables. Which also means you are better balanced left to right...which means even better stereo imaging and timbre accuracy.

So yeah, lots of good can come from it - but it's a lot of work getting it right. Everything would have to be measured individually, and as a whole, in the room and adjusted accordingly.

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Now, old school Bi or Tri amping is nothing but having an amp for each frequency fed into it's respective crossover section. The only benefit really is the dividing of the workload (frequencies) to different amps. Sure it can sound better, but I like the modern way of doing it...it just makes so much more sense (when done correctly with the correct tools)

I love your succinct description of the moving parts involved here Raven!!!

Does anyone else have anything to add about multi-amping?

Brian

I bi-amp on both my systems (Rachael and Torii 3).

For me, bi-amping helps take advantage of a larger woofer in an open baffle configuration that I feel needs more power while maintaining that sweet Decware sound going to the full range driver.

You will always be sending the sound through x-over components unless you use a full range speaker or you do what Raven said and digitally split the signal before the amps.
I bi-amped my full range speakers for a little while. A little different because it is a full range Fostex speaker with not x-over parts. But this driver starts to roll off at about 15k. So I added a tweeter to take over the 15k and up frequency. Also the tweeter was not as efficient as the main driver so I used the volume control on the SE84CS amps to balance the sound and used the pre-amp to control the main volume. This actually worked pretty good and gave me that sparkle up top. So I had one CS amp for the tweeters and one CS amp for the main drivers. The tweeters had a cap on it to stop the 15k and below frequencies and the Fostex driver did not have and x-over parts on it.

Pal, you are right, bi-amping/crossovers are not bad. You just have to experiment to see what you like and what you want the final sound to be.
I will be doing the same as you soon, once I have some time to make my open baffles for the Augies that are just sitting there in boxes. I will be running them off an Adcom 100 watt amp through a sub crossover box. I will start at 80hz and go from there. I actually wish I had 3 outputs from the CSP2 pre so I could do all three at the same time. So I guess I would be in the Tri-amp camp. I think this would be ultimate way to tailor the sound to what you like or feel that day. The Fostex have beautiful mids, but lets say you want more bass, so turn up the bass, or less highs, turn down that amp or off and let the Fostex take care of the highs. I will probably end up doing this in the future.  ;D

Hi...i am a new user here. I think the modern thing that is in vogue is having high end digital processing that highly tweaks both crossover and phase - so each amp not only gets *only* the frequency it needs, but everything comes out of the drivers time aligned for better cohesion of the overall output. Having everything done digitally *before* the amp is not only highly accurate, but you aren't losing watts, nor at the mercy of a crossover and all it's passive parts and their variables.