I could not eliminate the peak/null at around 60hz in my test room by moving subs around. I tried several locations. The response didn't change enough to warrant more graph pics. -just a differing level of nullness by a few db or so. The dual setup pictured was the best response overall. What was interesting is how the bass hump changed shape as I moved things around. It seemed to remain broadest at the 1/3 locations and become more peaky as I moved away.
My seating location must move to improve things I would say. Not worth it to smooth a 7db null. In content I couldn't ever reliably tell a null that size was present anyway. But it was an interesting test.
"We only started "fixing" rooms when we started measuring rooms." - Floyd Toole