Description of the problem: when the computer is connected to the DAC, extraneous sound from the speakers appears. The sound resembles the work of the operating system (squeaking and crackling). This sound is heard at a volume higher than average if you put the song on pause, and also heard in the song, when there are quiet moments in it.
Welcome to the forum.
Do you have another USB cable that you can temporarily try using?
What happens if you connect the USB to another of the ROCK ports?
Is the NUC and Amp plugged into an outlet with a surge protector?
Restart/Reinstall the Roon App to generate a new Roon folder
This sounds like it could be due to one of the devices in your chain, have you tried removing or temporarily replacing either the DAC or PreAmp with another one as a test? Do you have any other ones around the house you can give this a try with?
I tested three DACs: Cambridge Audio CXA-61, Exposure XM5 and AUDIO RESEARCH DAC-9. There are no extraneous sounds when connecting Cambridge Audio and Exposure. AUDIO RESEARCH + Marantz PM10 - there is an extraneous sound. AUDIO RESEARCH + Prima Luna Premium HP - there is an extraneous sound. Prima Luna EVO100 + Prima luna Premium HP - there is an extraneous sound.
Was your laptop on battery power at the time or plugged in? Noise in the system is often related to grounding issues/EMI noise from PC.
Since the issue occurs without Roon running, we can’t really advise further on the hardware aspect, you should reach out to your Roon dealer if you have one or your local audio store to investigate the grounding issues.