I am planning new home theater with a Seymour acoustically transparent screen, locating left, center and right channel speakers behind the screen. I am considering Altec (Great Plains) 604-HIII or JBL3677 or C211. The theater dimensions are 12' x 20'. The screen and speakers will reduce the apparent length of the room, so it will appear to be more like 16 or 17 feet long. I would like to do an Atmos set-up with speakers on the sides, rear and ceiling. Thoughts about what would be best for those would also be appreciated.