if your DAW gain stagging is correctly set, the D/A should output the same volt level the A/D saw when tracking.
if your DI out and Reamp In has basically 0db level change, you should be set.
I have the interface levels on my converters set to -10dBV
the way I test my system is I track a short clip recording the Mic and a DI. I reamp the DI and record that. then I compare the RMS levels. another way would be to run a test signal from the DAW out and back in thru your Reamp-DI box. But since I only have one Redeye box I can't do that because it's either DI or Reamp, not both at the same time.