David, this has been discussed at some length here several times. Although some manufacturers include a so-called "biamp" feature in their receivers, this is a misnomer, isn't true biamping and has no advantages. Biamping requires two separate amplifiers(as the term implies)and a separate external crossover before the amplifiers so that each amplifier gets only the appropriate frequency to amplify. The "feature" in question here simply feeds the same amount of maximum voltage that the receiver power supply section can deliver(and the same full frequency range)through two sets of output transistors(one previously unused for back surround speakers)rather than one; maximum power available isn't doubled, as is sometimes claimed, or increased by any amount.
