the room is about 2500 cubic feet. sitting 13.5' from the screen, F/R is about 15' from seating, side surround are 8', and the back surround are 4' from seating.

and for the small sub that's only 175W and max can go down to 35Hz (optimum I think aroung 50Hz), would it be better if i place it at the back of the couch for the mid bass feel?