I had a 950, but always ran it in 5.1. I suggest you contact Outlaw directly, either through their forums or support. Their support is outstanding, and you would get it right from the horses mouth, so to speak.
I would try calling Outlaw directly (1-866-OUTLAWA). You can also try the Outlaw web site and download the user's manual for the 950 preamp. Page 16 has the answer to your question, but it looks as though Outlaw is suggesting using eight speakers (including the sub-woofer). Their customer support is excellent, so a phone call may be the way to go.