Thank you both for responding. I think you both answered my question, though in different ways. I also think I worded my question confusingly; perhaps my question should have centered on the optical rendu.
I don't have a streamer. I have had a couple streamers that worked with my dac but I replaced them with the optical rendu, running Roon. My dim understanding is that the rendu is a bridge and connects "directly via usb to the dac." So my question is really: if a dac has a usb input for the rendu, then does it matter if it's "Roon ready" or knows anything about Roon? I take @audiotroy's response to mean that it doesn't; I just need a usb dac.
I don't want to confuse things but one reason I'm asking is that I'm curious whether I can connect my rendu to a portable headphone dac/amp that has only a micro-usb input and doesn't appear to be roon ready. More generally, I'm curious what I need in a dac to run roon from the optical rendu, other than a usb input.
Again, thank you for taking the time to respond!

