CB, I really can't see why you would need a separate amp for your setup. The Anthem may be an improvement over the Onk...
Hey Mojo, yeah I know I'm probably overkill in my space, (5.1 was all that was recommended for my small room) but I have no issues with that! I would love to add another sub actually. I love my current EP500 and would add an EP800 if I could. I am surprised how much difference you say the QS10 makes over the QS8. I was initially interested when they 1st came out but then figured surrounds wouldn't make that much difference - especially with my satisfaction in the way the QS8's perform. You are making me reconsider. I wonder if just upgrading the side surrounds would make sense and leave the backs at QS8? The M5's v4 were a nice upgrade for me for sure though.
Regarding the Anthem, I thought as long as you had ample overhead and clean power there wouldn't be a sound diff - or not much. The Onkyo is showing me otherwise vs my Pioneer. That's why I am thinking Anthem, even though I already have 'enough' power for my room. Just want to see if I can up the overall quality.