New, although a corner location for a sub often gives both the strongest and smoothest bass, when the room is square this can create a problem, as has already been mentioned. The room mode for both the length and the width at about 40Hz(560/14)will be overemphasized and a smoother response is likely to result if the sub is moved out of the corner more nearly to the middle of one of the walls, e.g. inside one of the M22s or along the wall to the left or right of the listening position.
The QS8s should be a couple of feet behind the listening position and separated as widely as possible, since they are side, not back, surrounds in a 5.1 setup. Experiment, and good listening.
