If you want to stick with the known quantity kind of gear you could spend around 2K on a Denon AVR-4311 or X4000 plus a Emotiva XPA-3 or an Outlaw amp for a little more. Spend the remaining 7.5 to 8K on speakers and subs. Or you could save the 0.7 to 1.5K for a 2 or 3 channel if you are willing to give the 4311 a chance to see if it can handle the speakers all by itself. If it can, then you are better off spending the extra money to get a better sub, or two subs.