Sure…
First the external source needs to be set at a healthy level, which makes the LEDs go orange and possibly flash red here and there, definitely above green.
A trick I found is to use the noise gate which gives you a db reading, and crank it up until your signal disappears, this will tell you what the OT thinks the input level is, hitting at -20db to -12db seems good to get a healthy signal and still have headroom for OT to sum.
You can also open the audio editor while recording and watch the waveform, changing your source volume until the waveform is around 70 to 90% of the available height in the display…
Since one might often be monitoring a source elsewhere and reroute to OT for sampling, the following settings will ensure the same volume is heard when switching from the other monitoring to monitoring through the OT:
For all:
Master volume: 19
If using a master track: track level 127
Mixer direct monitoring: dir 127
Flex playback of buffer: track level 127
PU: track level 127, monitoring level on rec pg2: 127
Thru: track level 127, amp vol +49
Any values not listed: default
I’m sure there’s other ways to go but this setup works great for mixing and matching monitoring of external gear for sampling/looping/fx processing and maintaining constant volume… 