I think the answer to Simon’s question depends upon how the DAC is connected to his endpoint. If he uses S/PDIF (coax or optical), then Roon’s RAAT protocol definitely has no way to know about the connected DAC, and all DAC specific settings must be done manually at the corresponding endpoint’s device setup in Roon.
If, on the other hand, he connects his DAC via USB to his endpoint, then RAAT has the possibility to discover and interrogate the USB-connected DAC and configure automatically the DAC’s capabilities in the device setup.
Take for example my current system path. It shows a non-Roon Ready DAC, connected via USB to a RPi4 running RoPieee. Some other DACs can report their make and model, without need to be Roon Ready certified:
