I have the luxury of converting a room above a garage to a listening room it is 20X24 with a vaulted ceiling. One end has a stairway to the garage. I can build a knee wall to form a corner for a horn by the stairway. What are the requirements for the knee wall. More than 48 inches tall? I have utilities right at the corner and I will need to build it "out". How long do the 'walls" need to be before there is a transition. I am thinking MDF and paint. They need to sound good but not necessarily look good. Any advice on MDF horns? Thanks to all. B