Low level imput recording from a Digico S21 using USB port

[Juan Libertella]

The previous Saturday I had to record a live show and I had to connect to a Digico S21 mixer through the USB port (UB Madi), I recorded 32 channels without problems using the ASIO driver that I downloaded from Digico. The problem is that the audio signal coming from the mixer arrived with a very low level and very different from the level indicated by the mixer's meters. Does anyone know why this happened? Reading the manual I didn't find any reference on this subject, thank you very much.

[John Vere]

The levels are always set at the audio interface before heading off through the USB connection. The DAW has no control over this level but one can most certainly check it by arming the tracks and observing the DAW’s track meters. 
Some interfaces do have a software mixer in line which you also need to check. 
The good news is because it’s digital it should not matter and all you need to do is apply gain or normalization to the tracks. 
I’ve had plenty of low level tracks from live quick mixes and what was easiest was highlight the whole project and apply Normalization at -8.0db.