Don, I got dizzy reading Dave's description, and I'll mention the simple brute-force approach that I use in my three listening rooms. Good quality electronic components are so inexpensive these days(e.g., refurb receivers for $150)that the way to enjoy independent source material with independent volume control in each room is to have the necessary equipment in each room, with each being totally independent of the others.

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Enjoy the music, not the equipment.