I was looking at my MCACC results yesterday and noticed that each channel's gain was being brought down by 4.0-4.5 db. I imagine this setting is done to level the volume from each speaker, however, each speaker was being brought down a minimum of 4db. Is there some other reason for this like calibrating the volume to reference level (0.0db) on my receiver? Or should I just edit them to only show the difference? (i.e. towers set to zero, center to -0.5db)?