Well Lou, for me I'm just not a fan of subs as coffee tables or end tables. Many put them there to disguise there nature, and possibly gain an advantage of near field response. IMO, they probably never measure worth a . If they do, great. I placed mine(after trying a couple spots) behind me because I was afraid of destroying them since I have lots of airspace on concrete, and to retain some tactility. As tesseract said, these just happen to be at 180, and the 3rd sub up by the mains is at 0. I've tried every combination of phase and that is the best in my room. Your room will ultimately dictate the response, but if you go behind the LP I'd surely try the sub at 180, and every point in between.