Steve, we can always make it 21. No, you can't bi-amp with a receiver, despite the terminology that some of the manufacturers shovel out. A receiver has only one amplifier with several channels of output transistors to distribute that power. Distributing the power through two sets of output transistors rather than one doesn't double the power as some imagine and can't increase the power available from the one power supply section in any amount.

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Enjoy the music, not the equipment.