A coworker of mine put in QS4s into a rather large room (pretty much 50% of his whole basement is wide open), and they do a respectable job even in such a large space.
With that said, they don't go as deep as the QS8s of course, and I think that he could really benefit from the QS8s instead, but he still does alright with QS4. Of the two, I've only had QS8s and really liked them. I don't have them any more as I are stepping into the next realm of home theater sound with Atmos and DTS:X, so I traded them in for some on-wall M3s that I am absolutely loving for accurate immersive sound imaging.
