Thomas, I’m going to close this Support request because it’s more in the nature of a Feature Suggestion than a Support Request.
You are welcome to ask for Roon Labs to recognise the C510 as a Roon Tested device, complete with its own icon. However, I see that the C510 is no longer manufactured or sold by NAD; it’s a discontinued product. I feel I should point out that the likelihood that Roon Labs will devote resources to fulfilling your request are slim because of this.
However, as has been pointed out to you, Roon will play to your DAC.