David...youv'e lost me a bit there..I set the master volume at reference "0.0db" to read 75db on SPL ... to my surprise the reading was "85.0db on all speakers" in the front row; and "80.0db" on the back row :unbelievable: ... to get the 75db I had to use the volume at "-10.0db" and "-6.5"
If you have a reading of 75db on the SPL..with the master volume set at 0db.. that has to be coming from one of your front speakers, in which case you would have had to adjust the volume trim to get that reading..!! :scratch:
Then all the other speakers would be adjusted with the volume trims to read 75db..
I don't understand if you've set them all to 75db..that your'e now getting a reading of 80 -85db.!!