I have an unusually shaped room so would like to use the QS speakers for surrounds. All the advice I've seen suggests QS8s for "large" rooms and QS4s for smaller ones. My question: What's considered a large room?

The room I'm working with is four sides of a pentagon with a flat wall across the back. It's 12-ft. deep at the deepest part, where I have a counch against the wall. The monitor is opposite. Overall length of the room is 25 ft. I'll mount the QS's on walls angling inwards on either side of the couch in a 5.1 configuration. Also the ceiling is vaulted -- 25-ft. at the peak, down to 10 ft.

If you can even picture it from this description, is it large or small? QS 4s or QS 8s?