Source file: WAV44/24bit/Mono
If I wanted to do a basic cleanup/sweeten in Audition of this mono voice recording, would I perform the edits BEFORE converting to stereo or AFTER?
Thanks in advance.
The decisive step for answering this question is the "converting to stereo" step. You are adding another dimension not present in the original after the step.
If this step is done with a specialized convert-to-stereo filter (like there are special ways to add color to black-and-white films), your preprocessing in mono should be focused on improving the match of this process' assumptions with the presented material.
That is, you are going to try equalizing artifacts of the microphoning and equipment, then do your mono-to-stereo conversion, then do the work focusing on improving the quality to the listener.
If your mono-to-stereo conversion is just "make two copies of the mono channel", then it's pretty much all the same what you work with apart from filters with explicit stereo output like most reverbs and stuff like Leslie simulators.
So basically you first do work in mono for the sake of the mono-to-stereo conversion, then you work in stereo for the sake of the listener.
When the mono-to-stereo conversion is trivial, the point where you go to stereo is somewhat arbitrary, but don't go back to mono after explicit stereo effects.