I am planning to use a pull down TV wall mount that is built to allow a TV mounted above a fireplace to be pulled out and down.
Instead of mounting a TV on it, I would mount a diffuser slightly larger than my TV that would be above the TV when I am watching television and would swing down to cover the Tv when I I am listening to music.
My only concern is that the TV would be too far off the wall when is is the down position. to that end i am still looking for one that swings more "down" and less "out".