Can I suggest my alternative option, since it may help some users here.
If you need it to be out of the way, not seen, and certainly not heard.....
Why not use an older Wifi Router which supports OpenWRT or one of the many Thin Client PC's on eBay??
I actually have a Netgear WNDR3700 I never got rid of from many years ago which was given to me for free from my housemates at the time since something related to the Wifi stopped working and nobody could connect to it, but it worked fine wired and otherwise. This unit has a single USB 2.0 port; I use it to connect a bus powered DAC since probably 5 years now and run MPD on the OpenWRT OS.
You can use any MPD client to connect and control the device.
Simply turn off all radios in OpenWRT.
My music library is hosted via a USB SSD which is attached to my main router.
Very simple setup; the router shares the Music directory to the OpenWRT device, the OpenWRT device has this directory mounted to where MPD can see it, MPD cycles through my albums indefinitely as I've configured it to do and I can sign in from any browser or mobile phone app to change my song / album / settings.
Before OpenWRT was sophisticated with package management, it would have been a big pain to set this up. In those days I previously used a HP Thin Client, with some kind of Atom or Celeron CPU, which consumed a low amount of power, like 25-30W. But the Wifi Router with all radios disabled only consumes maybe 7W, and the DAC is not even consuming 100mA, and the SSD should not be consuming much power either so it's a very efficient setup.
With that said...
If you're the kind of person who needs this PC to be a desktop substitute, well obviously a repurposed wifi router isn't it. But if it needs to do music playback ONLY, and do so reliably and without noise or cooling, and you aren't scared of a little command line for setup, I think it's a great choice that is hard to beat in terms of efficiency, customization potential and reliability.