Teunis,
It appears my .wav files were too hot.
They all had some clipping where mp3gain wished to reduce the overall value.
I had mp3gain set to the default (89.0 db) for the analysis.

I'm thinking at this point I should load some biab arrangements (say one of my sets), adjust the mix in biab to a lower level, output the mp3's the set into a folder and then let mp3gain adjust them all to the same gain.

I do have a problem with my sets in that some backing tracks are noticeably louder than others.
It would seem this effort would correct it.

I will be switching over from .wav to .mp3. I assume I should output normalized,mono at 320kbps.
I use mono tracks as my amplification is a single speaker.

Thanks

biab2024(Mac) Latest Build
Mac OS Sequoia 15.0.1
Apple M2 pro 32GB Ram
Logic Pro 11