I currently am using a 990/7500 to run a 2.1 system made up of a REL Q401E Sub and Monitor Audio GS60 towers. I am Biamping the GS60s, and have one channel left over that I will most likely use to add a center channel with at some point. I am also planning on trading out the REL to the newest Flagship sub from Monitor so that it not only matches the Speaker finish (Santos Rosewood on the Monitors, Crap flat Black on an overly expensive REL) but the newest sub sounds amazing. I just got done doing a system using 5 of the new subs along with 7 of the GS60s in a 7.5 setup for a client and was blown away.
As far as how my system sounds? It is incredible. I am a Monitor Audio Dealer and have heard these speakers used with amps from Krell, Denon,Onkyo/Integra, Anthem, Parasound and a Threshold. Now I can say I have heard them with Outlaw as well. Out of all of the amps I have listend to these speakers with, only the Threshold sounded better than the Outlaw, and just barely. It may be due to me Biamping mine, and the Threshold system was just single wired, but it was pretty damn close.
So far I love this setup.