We have a new constructed room with the dimentions of 16ft. wide, 22 feet long with a cathedral ceiling. We are purchasing a 60 inch TV that will sit in the corner of the room. Where is the best location for the 4 wall mounted speakers of the home theater system. Should the speakers be at a diagonal in the corners, or flat mounted on a wall and how far up the wall should they be mounted? The contractor is putting dry wall up tomorrow and we need to tell him where to put the speakers right away. Any advice will be greatly appreciated!!