Questions about using the signal from the Roon Core server direct to playback system

It depends. If you are connecting the endpoint and the DAC via AES-EBU or SPDIF then that is it, Roon just sees the endpoint, not the DAC beyond.

If it connected via USB, then there is a chance depending on the endpoint and DAC that Information about the DAC gets reported back to Roon.

For a thorough discussion, read this post: