Originally Posted by fjames
You can look at it a lot of ways, I was just doing the simple math - more total power. That the power supply in most AVRs is inadequate doesn't count, it's like saying you should only run a 7 channel AVR with two channels to save the power supply.
For me the main thing is (just my theory/POV) getting the best power to the high frequency section. Without having to share with the woofer, I figure you've at least got a chance of cleaner power to the highs. Of course, you're limiting power to the woofer, but problems there are much less fatiguing/annoying than treble issues, and the sub helps. Some people say that the highs need much less power, and that's true in steady tone testing, but treble transients can suck a lot of juice, so every little bit helps.
There's a reason that, for exmple, JBL's roughly $4700 each VT4887A line array speaker units have max continuous power of 1000 watts for the low frequency driver and 225 watts for the high frequency driver. It's not because JBL wants them to blow up under normal conditions of use. It's because there is just less power needed for the treble energy in real content. Peaks or no.
FIgure the tweeter content will be around 20 to 25% of total power and you're right about there. So biamping is highly unlikely to limit power to the woofers because unless you play white noise very very loudly or have a catastrophic failure of some kind, the treble side amps will never get anywhere close to whatever their full power is, even if you have to double the power to account for a 3 dB pad on the tweeter (often significantly more efficient than the woofers). And you'll theoretically add about one dB to the potential clean SPL of the system, maybe.
As I said above, I buy the idea that if you are going to drive your system into distortion, biamping may keep the uglies out of the tweeter section, which can only be good for the health of the tweeter. But 1 KHz is pretty high, and your tweeter likely crosses over above that, meaning you'll still get to hear a fair amount of the distortion. As far as audibility, look at it this way: pretty much every guitar speaker whose specs I've ever looked at has a FR peak somewhere between 1000 and 2000 Hz then drops like a rock. The voice coil functions as a low pass coil, preventing that energy from reaching the cone. But you can sure as shootin hear the distortion in guitar sounds from Hendrix to EVH to Al DiMeola. If you biamp and drive the woofer amp into distortion that would be audible full range, it'll almost certainly be audible biamped. Just missing that sense of "air."