Craig, I read your post at AVS and you noted the 2 verticle 600's were firing to the rear wall, and the horizontal 600 and EP500 were firing into the room?
Are the verticle 600's in front of your seating or behind. Somehow I got the impression from the other thread that they were behind you and firing away toward the rear wall. But I dont think you stated that, and I don't have the thread open at the moment.
Just wanted to learn more about your placement and calibration, including phase. It's got to be more complex when dealing with 4 as opposed to 1 or 2.
