With the present set up, I would try the side surrounds, one near the top right corner and the other opposite, on the bottom wall near the chair. The sub should go on the wall on either side of the entertainment centre, but you may want to do the silly but often works method of putting the sub in your prime listening area and lay on your back in one of the proposed areas just to see what effects you can get. Just don't let the neighbours see you!!!
