Looking at other members home cinema set-ups and there surround placement, I have drawn this conclusion, one there too far towards the back of the room with a single pair of dipolar surrounds, the centre back is placed too far forwards, rather than mounting it to a secure surface, say the wall, this will give better reproduction of the low on the loudspeaker has well keeping within the proper specification layout, be it cinema or home cinema.
Now I have cut and pasted the position of the centre back surround in this image, to where it should go, and where it will perform its best, against a hard wall, more to come later.