My old Mac Mini running Ubuntu was also running its fan almost endlessly, so I ordered a CanaKit replacement Raspberry Pi 3 B+ kit. All in one: board, case, power supply, heat sinks. $55. You need an 8GB MicroSD card, too. This morning I downloaded Etcher and RoPieee, flashed RoPieee to the card with Etcher (trivial, couldn’t be simpler), assembled the board into the case (trivial; 2 minutes), put the heatsinks on the board (a small tweezers came in handy), slid the card into the SD card slot at the bottom of the case, plugged the case into Ethernet and power, waited 5 minutes for the autoconfig, logged into the build-in web server and configured the timezone and name, plugged in my Liberty DAC, went to the Roon Remote, which saw it fine, and enabled it. Now playing Mozart through it with full MQA “authentication”. So $60 for a Roon USB endpoint.
Shout out to @spockfish for making the software side of this so painless!