Perc, the equalization part of MCACC is more controversial, but the basic level calibration does a fine job and there's no good reason to expect that a manual calibration using a separate SPL meter would be more accurate(or even as accurate, considering the added factor of human error). You could nevertheless bump the center up a couple decibels. Another temporary check would be using one of your mains vertically in the center to see if audibility was better. If so, this might indicate that the present center speaker isn't adequate, regardless of the level set.
