But is it really biamping when it is being done after the amp instead of before, would you really have 240 watts per channel or just 120 to the tweeters and 120 to the woofers, Would there really be an advantage to doing it or any sonic value? maybe a good question for Dan B.
Jeff;
Of course true biamping is when you bypass the crossovers in the speakers in favor of active line level ones. So no, the method utilized in the receiver does not realize the full potential of biamping. However, it does provide an advantage to those powering speakers that need a little extra oomph.
Some advantages:
1) Extra 3dB of margin (2x power to speaker now)
2) As you know, the amps in most receivers are not as robust as dedicated amps, thus it will help them out to break off the speaker load to separate amps within the receiver, rather than to one amp in the receiver. For 2-way bookself speakers there is probably little advantage of doing this, but for Clints case where he had side firing 12" woofers, it is a pretty significant advantage.
3) You can boast to your friends that your biamping on a receiver
4) Why leave those channels unused in a 5.1 system? You paid for them
5) You can now tweak the sound of the speaker by altering the level of Zone2 (Which I recommend to be used for the low end of the speaker) so you can either add or reduce bass levels.