Sot, you ask "Does that sound right", but Micah justifiably asks you how does it sound. As has been mentioned, there are many factors involving different speaker specs and/or placement that could result in that trim difference being justified. Have you been having unusual difficulty hearing dialog or other center channel sound? If you simply run the internal receiver calibration sounds, does it sound to your ears that there's a sharp drop(you report about a 9dB lower trim on the center)as the sounds travel from left main to center and then a big increase up to the right main? You don't have to necessarily use an SPL to check for this difference. I have an SPL and my level measurements with it differ slightly from the Audyssey results, but I'd be a bit naive to assume that my human error is less than any error of the automated setup.
