[bpape]

Well, anything premade is going to require the seating to be out probably 17" or so and didn't think you had room to move that far. Build a simple frame and fill with standard insulation and wrap with cloth. Make it as wide (couch to wall) as you can, the whole length of the couch, and from the floor up to maybe 6" from the top of the couch. Cover with cloth. Nobody will see it and it will do a nice job of soaking up that corner behind the couch and knocking down the boom.

Bryan