Did you find any solution to the -6db problem you described? I’m having the same issue.
I’m recording to Pro-Tools with my 8 Channel interface, taking the signal straight from the direct outputs it has and inputting into the uTrack24 to have a backup.
When I open both audios on the DAW to compare them, the original always has +5, +6db than the backed up audio from the uTrack24.
If you have a solution, please let me know!