Originally Posted by bigguyca
Bias disclosure: I'm a fan of passive bi-amping. This is when it's done with amplifier channels that are relatively independent at the power supply level. AVR's don't meet this criteria, heavy duty multi-channel amplifiers are good candidates such as; ATI, Outlaw Audio, Parasound and likely others.
That said, for a full range, say 3 or 4-way speaker, one justification for bi-amping is to separate the heavy current requirements and stresses on an amplifier at low bass frequencies from affecting the amplifier's performance at higher frequencies.
For a 2-way center channel used for home theater, where the woofer-midrange covers the frequencies from 80Hz to say 2khz to 3kHz, the woofer-mid is already covering about all the content. There may a benefit, but just talking here it seems that it would be small, even for someone who likes bi-amping.
Now consider a big 3-way center like the Ultima Voice2. The woofer crosses to the midrange at 235 Hz and the midrange to the tweeter at 2 kHz. Adding a separate amplifier for the woofer from the midrange/tweeter will take a lot of the load off the midrange/tweeter amplifier. This makes a better case for bi-amping. The woofers however aren't covering below 80Hz in a typical arrangement, and the one recommended by Revel, so they aren't really as heavily (whatever that means) loaded as they might be, still moving larger (heavier) drivers at relatively higher frequencies can take a lot of power.
In a 4-way floor standing speaker such as the Salon2, the woofers cover from say 20Hz to 150Hz, with the remaining frequencies covered in three ranges. The Salon2 is meant to handle more power, there are three woofers and an input impedance that drops below 4 ohms for a lot of the range up to 1kHz. Such a speaker makes the best case for bi-amping based on sharing current load. Both amplifiers will still have a significant load.
Note that I really didn't directly answer your question! Listing tests with your equipment, in your room, with your content, your chosen SPL's, with your ears, are the best way to see if there are advantages. Some suggest driving one speaker as the best way to determine if there are benefits. This of course has the advantage that a test can be done with existing equipment since an amplifier channel, from another existing speaker, can be temporarily repurposed for use with the center channel amplifier for the single speaker test.
Listening tests such as these to me aren't that much fun so I only do them occasionally, often over several days. There is a definite learning curve for listening tests. It is necessary to try different material and identify specific small parts of the material for careful listening. At first you'll hear all sorts of differences and added items you didn't hear before. It's necessary get past this phase and consistently hear the material before conclusions can be drawn. Of course the conclusions really are very specific to the listener, but it's your system so it's your decision.
Stacking banana plugs make it very easy to switch between bi-amp and single amped. Room interactions and other variables play a lesser role when using a single speaker. The bi-amped Salon2 has a cleaner up upper and slightly better low end, even a low listening levels. There benefits were also present in the Studio2. I was surprised by that. The Voice2 difference was very subtle.
By cleaner, I mean less sound not more. Sibilants are more natural the upper end feels less “damped”.
Yesterday, I was listening to Christy Baron’s Nite and Day (HDTracks). This is a nice base line and trumpet that just sounds a bit more real when bi-amped.
Divorced from this discussion is disconnecting the lower and upper crossovers. Woofers movement also generates power. This has to be countered by the amplifier but the upper crossovers are awash with current and I assume voltage.
Couldn’t this voltage be in the range that is not rejected by the upper crossover and therefore have an effect on the sound?
After all, my plasma TV managed to do so even through the amplifier.