How does a computer with Roon from another room work with a DAC? It sends control info via wifi to router then this sends via ethernet cable (or maybe thru wifi, depending DAC) to DAC? What is the noise issue?
Here’s how I do it. I assembled a fanless Intel NUC i5 and I stalled Roons proprietary OS called ROCK they offer this for free but it only runs on certain NUC’s. It will save a lot of money over buying Nucleus mine cost about $700. If you have a DAC that takes USB you can attach the NUC to the DAC to your preamp. There is no problem with noise on USB from a NUC at least none I can hear. USB noise is another audiophile neurosis any modern DAC will filter it. Since you said your router is in the same room that’s the route I would take.
Router ethernet >NUC>DAC>Preamp. This is all controlled with an app on a tablet or phone I would use a tablet larger screen helps. The NUC runs the Roon core and also functions as a streamer. If you want the NUC in another room you can use something for an endpoint like a Node2i or even raspberry pi connected to DAC.
I have tried both ways and can’t tell a difference, at the moment I use a raspberry pi4 endpoint, NUC in my office they are both on the same network and I have a drive connected to the NUC with my ripped CDs on it. Roon shows them all in a library structure.