Additionally, if you have a lot of space, M2s may be a more economic choice. The QS speakers claim to fame is the diffuse sound field the present. But given enough distance a mono-pole speaker like standard book shelves, which is what I'm using now, can also have their sound spread out.
While I am a fan of adding rear surround speakers, I'll admit there isn't much content back there (even when using PLIIx to expand 5.1 to 7.1), so a speaker as capable as the QS8s are not really required. QS4s should also fill in fine, if you're sitting within the 4' range.
But yeah, start with your 4.0. Get comfortable with that setup, and when you're ready for us to spend more of your money, we'll be here.
