Help with UR824 Signal Flow Path

Been using the UR824 for a few months. Works well - but I need some help in understanding the signal flow thru the device. I have an image of the operations manual block diagram attached to this post (hopefully its not a copyright infringement).
BlockDiagNotes.jpg
I have marked on the attached my understanding of where the controls are for each signal path. I tried to indicate which controls are available within Cubase and which are only available from dspMixFx. As you can see, I have one area of confusion. I don’t understand where the DAW return signal control resides or why it is needed within the 824. It would seem to me that Cubase already has its own output control in the mix console.

You all have much more experience with this equipment than I. Maybe someone can look at the markup and let me know where my understanding might be incorrect.