The rear surrounds can me moved back as far as you like. The distance you have would allow for direct radiators to be used, like the M2 or M22. They will throw the sound out more directed at the listening position but with that much distance a good deal of horizontal dispersion will be taking place. If you mounted them about 5-7 ft apart that would ideal as you say they are 7ft behind.

Last edited by jakewash; 05/14/10 05:50 PM.
Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70