I missed your post before. I think we are saying the same thing from the opposite direction. It really depends on the room you can have large bright room or a dead one. Unlike music studios where the acoustics and monitors are referenced to "flattness" The x-curve is reference made from the measurement of many (100's, 1000's I don't think I have ever seen how many) The theory being it the mix theater sounds like the average theater(I would say response, but it not really what we consider response today since it only frequency) so it should sound very close to what the engineers mixed. So I design mix theaters to support x-curve in the other control rooms which tend to be much smaller those I design to be flat. You could apply an x-curve but you are doing it in room that falls into small room acoustics which the x-curve was not designed for, it is getting into the same problem as using x-curve in the home theater. I'm probably about as clear as mud in this post.