John,
What's the dimensions of the room you are putting it in? Sometimes you can get a better bass response by NOT putting the sub in a corner, but by moving it into the room a bit. Most of us just shove the sub in the corner because: it's a huge old black box that is hard to get around, bass (LFE)is non-directional sound, and our wives can't stand it to be anywhere else.
So what size of room is this and where are the openings? You could probably easily put this sub somewhere other than right next to the screen.