I pulled the center out and it does not make a difference. I turned off MCACC and it sounds much more full. With MCACC on, it filters out all the background noise and focuses on the vocals and so it sounds more hollow.
I guess in the end, the hollowness is probably all subjective to me and I think this hollowness is how it is supposed to be. But the tuned focus on the vocals sounds too studio. It stands out too much and therefore artificial to me. For example, there can be a scene with explosions all around, but the guy yelling sounds like he's sitting in a quiet and calm studio. It does not blend with the scene to me.
Some good came out of this because I found that I like it better with MCACC off. To me, the center does not stand out as a loner from the other speakers and it just sounds more full and synchronized with the other speakers and the surrounding scene.
