it will help us to help you.
if you specify the Lineup level in FCP in dBFS and the country you live in.
deck's are tweeked differently in some region's of the globe. next to that
where are your PPM's in the system before or behind the deck???
aren't you using embedded audio ????
you say you use murraypro
as i watched there website your using BBC scale PPM's ??
as far as i know (not sure did not use BBC PPM's that much)
4 on BBCscale = 0dBu = -20dBFS