How about two boxes?
The Model 7000x amplifier offers common mode rejection on its balanced inputs and 7 x 130 watts into an 8 ohm load. We have never offered this much power, along with XLR and RCA inputs, for this kind of price! Manual See Front Panel Huge See Rear Panel Huge
outlawaudio.com
plus
AT524NC 4-channel Amplifier (200W RMS per channel) $2,995.00, or
The Model 5000x is an update on our previous high performance, affordable 5-channel amplifier, the Model 5000. Still rated at 5 x 120 watts into 8 ohms or 5 x 180 watts into 4 ohms (all channels driven), the 5000x is ideal for those who have moderate size living areas and desire a 5-channel home...
outlawaudio.com
either way you end up with a spare amp channel.
If it was my decision, I would go with 3 boxes:
The Model 7000x amplifier offers common mode rejection on its balanced inputs and 7 x 130 watts into an 8 ohm load. We have never offered this much power, along with XLR and RCA inputs, for this kind of price! Manual See Front Panel Huge See Rear Panel Huge
outlawaudio.com
plus
AT523NC 4-channel Amplifier (200W RMS per channel) $2,995.00,
plus
Mono? Mini? Micro? Magnificent? Whatever that M is, this is one UNREAL little single-channel amp. 200 Watts (conservatively!) into a 3-inch chassis with balanced input stage to offer Common Mode Rejection! MANUAL See Front Panel Huge See Rear Panel Huge
outlawaudio.com
Or, sell the AV7705, grab an AVR-X4700H and an AT523NC for best performance.
The drawback with prepro is, if you want to do 11 or more channels, it will cost you a lot of money on power amp, when the built in amps of an AVR such as the X4700H, or Yamaha's equivalent will be more than adequate for the surround and height channels in many cases.