My room is about the same size as the OPs. My couch is about 3' from the back wall, so I went with wide dispersion in-wall speakers ( see sig. ) for the back surrounds. They work well enough that my guests jump out of the couch when hearing sounds behind them. Just saying that 7.1.6 is certainly doable in a room that small. What works out even better for 4k material is that I'm sitting a little over 9' away from an 85" TV -- perfect!