[amathie]

Hi Joachim,

That's brilliant! It works like a charm.

SUMMARY OF ISSUE AND SOLUTION FOR FUTURE REFERENCE:

BACKGROUND: I want to be able to process the front stereo pair (L and R) and/or the rear stereo pair (Ls and Rs) of a 5.1 mix, independently from the rest of the channels, with stereo processing. It is not possible to achieve this using an insert on the 5.1 channel which must be either a 5.1 or multi-mono plugin.

METHOD USED:
Take the 5.1 aux (the channels of which you want to process independently) and send it to another 5.1 aux using a 5.1 bus. Create subpaths of this bus corresponding to the channels you want to selectively process. So, for example, I created two stereo subpaths, the first for the L and R channels and the second for the Ls and Rs channels. Next create a Master fader and allocate it to the subpath you want. The Master fader now allows you to insert a stereo plugin to process that stereo subpath independently.

COMMENT:
In effect, rather than putting a plugin insert on a 5.1 channel strip, you are creating inserts on selective subpaths of a 5.1 bus between two 5.1 auxes. These inserts are provided by Master Faders. This works really well and allows a lot of flexibility.
Being new to Pro Tools I thought that a Master Fader, with its post fader inserts, should only really be used on an output. In this use, it is ACTING AS AN INSERT in the subpath of the bus between the two aux channels.