I'm slowly working towards 9 or 11 channels.
My reciever allows 2 different 7.2 layouts, one with front presence, one with rear surrounds.
I'm going to have 6 QS4's for all my surrounds soon. I haven't decided on the placement yet. Because they are supposed to be forgiving of placement I may try placing the side surrounds at 85°, the rear surrounds at 115° and the presence at 55° all at 5'6" off the floor. These would end up roughly 5' apart in my living room. I've decided against placing them a over the (exterior) door.
The new reciever has to wait. I'll have to suffer with 7.2 until my third sub arrives ;-) (its a tear, not a wink)
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3 M80HP
2 QS8
2 QS4
RX-A1010
ADA 1000-4
PT-AE8000
PS4
Seymour XD
7'x 12'x 21' cave
3 Paradigm subs