The max volume on the earpiece is the same for all the files I edited (i.e. FFFF). It's how I handle ramping down from that max volume that's different between files.

See my EDIT4 though in opening post. Turns out there are other fields that are no where near max that also combine to set volume. Combinations are endless. You should try editing the file yourself. It's dead simple. Levels just vary from 0 to FFFF hex. 6 Levels exist.

It's easiest to view in Excel. But I edit in notepad because I want to avoid excel adding some junk to the file.

Speakerphone adjustment is up and difference on that is even larger.