Kind of frustrating that no one answered this, perhaps because it can only be done from inside your DAW and accessing it will be different for everyone, but still...
I am using Logic Pro 10.6.1 and have the Quantum selected as both my input and output in the Logic Pro->Preferences->Audio... then Devices tab. **If you have anything else selected as output (ie USB Audio CODEC, Built-In Output, etc) then you won't be able see the following information - Quantum MUST be set as your output device**
Next navigate to the Mix drop down menu and select I/O Labels, there you should see all the default assignments (procedures vary on how to get to this information depending on your DAW, but each should allow you to see/change these) :
Output 1 - Main Out L
Output 2 - Main Out R
Output 3 - Line Out 1
Output 10 - Line Out 8
Output 11/12 - Headphones 1 L/R
Output 13/14 - Headphones 2 L/R
Output 15 - SPDIF Out 1
Output 16 - SPDIF Out 2
Output 17 - ADAT Out 1
Output 32 - ADAT Out 16
Hope that helps.