inset the speakers so that they are flush with the top, rather than having them stick up completely on top. just a thought. to do this, use 5/8" mdf as a final top layer. cut the 3/4" mdf to fit the speaker hole, and then the 5/8" mdf on top to fit the outside edge of the speaker. that way the subs will sit flush instead of sticking up like that. just a thought.