B- P5 would probably be enough, but a P-10 would be better. I think its better made than the p-5 and its also much quieter since it doesn't use an internal fan, due to its heatsinks. With the P-10 you will also have more headroom which is important to system dynamics as well as future expansion. Those extra outlets are "hi-power" outlets, not just regular ones.
With my system, I discovered at IDLE each side was drawing between 500-550 watts. I have 1 P-10 for each side and not only did the system get quieter due to reduced THD (from .4% in to .02% out) but micro-details as well as dynamics actually improved.
I would get the p-10 - no question. You might then be able to lose the QLS 6. In addition, the real world price difference is not as large as you might think between it and the p-5, especially if you contact my buddy Walter at Underwood HiFi and tell him I sent you. I've bought 4 of them from him and have had no problems whatsoever. I've also discovered the HD pcs play really well together with the P-10's.
Good luck.
Harve