For a desktop OS, I have been recommending Linux Mint to new Linux users. The UI feels familiar to a Windows veteran, and the initial setup is designed to be user friendly.
However, don't fret too much over it. Distros are mostly just a pre-configuration of the OS, all of them can do everything.
The $9 Apple DAC is unironically good. I can confirm it is plug-and-play with Mint.
Edit: To be clear, it is good if you just need an audio output (the core feature of a DAC). If you want crazy DAC features, it clearly isn't it.