the "right" sound mode for all my BDs

[brad1138]

I have a 7.1 system. I recently upgraded to a preamp with HDMI. Some of my BDs are DTS-MA others are DD TrueHD. Some are 7.1, more are 5.1. If I want my rear speakers to have sound with 5.1, I need to use some sound processing. I have been told to just use PLIIx for everything, but PLIIx is a "Dolby" format, is it right for DTS-MA movies?

I have been reading about PLIIx and some places say it is just for turning 2.0 into 7.1, other places say it is basically for anything that is not 7.1, to turn it into 7.1.

Basically, there is a lot of confusing and contradictory info out there, I am just trying to get the "real" answers.

thanks