PeterChenoweth, thank you for the detailed explanation.

So I need to run a test tone and raise the main volume of my receiver until I hit 75 db using the spl. The run the test tones for each speaker making sure they are all 75db.

I think I would have to have each speaker slightly different to each other as I am not in the center, Maybe I would have a difference of -2db for the speakers closest to me?