The screen will be mounted flat against a wall; the speakers will be recessed into the wall. I have a large "crawl" space behind this particular wall, so I need a means to support and further protect the speakers, hence the boxes. I will also then be able to access the speakers from the back side of the room, which will keep me away from the rather delicate perforated screen I am purchasing. I could, of course, hang the screen from the ceiling and place the speakers on stands behind the screen, but then I'd be losing about 20" off the length of the room.
