IMO you could probably go with either a horizontal or vertical center then. Things I would consider are what your primary use will be, how close you will be sitting to the screen and how far to the sides the widest seating will be.
Cheers,
Dean
I will only be using the speakers for watching movies, no music. We will be sitting 11' from them, and the farthest sitting position will be about 2' either side of center (usually only going to be two people watching at one time).
I was planning to place the M22's about half way between the left edge of the TV to the wall (as seen in the third picture), and whatever that distance is from the TV, the same for the right M22. Course I'm open to suggestions on this as I have no idea what the rules are about how far to place the LR speakers from the TV.
