I don't normally post experimental layouts here, but I'll make an exeption and put this out there for general comments.
This layout as 1/3 octave spectral EQs added on the Rears in the ArcTan Method. See the new check boxes at the very bottom of the ArcTan controls.
These Spectral EQs are really pushing Plogue's limits and I had LOTS of crashes getting these installed so I can't swear to these being very stable. 64 additional sliders! Save Often!
The idea here is not to boost wanted sounds in the rears but to cut unwanted sounds. You may also want to try cutting out stuff below 200 Hz, if that's not adding things to the mix. Sould result in tighter bass and cleaner sounding rears (we Hope).
I'm going to keep exeperimenting along some of these lines but would appreciate feedback on what we have so far.
As an expeiment, I did this in the most simple SPEC layout, rather than the more complex, so this may not be sutied for actuall conversions with ZAG/PTA etc. but is just meant to listen to and see if we're headed in a good direction.
One last Caveat, I normall don't save layouts for posting with controls open on 2nd or 3rd monitors, but I did in this case (again,

this is an experimental layout

) Plogue is supposed to not open things on monitors you don't have but if you can't see the contorls on this layout let me know and all re-post on one monitor.
SPEC4.3.2 Simple Rear EQ Test.rar