CDC2,
super curious, do you work for the center for disease control? If so, we may have a friend in common!
my Mac mini is also old - vintage 2010, las of the onboard optical drives. I also struggled with it for a while, trying J River, Audirvana, pure music, etc.
Roon was the game changer. No need to do the shared screen thing, Roon works with a controlling device (phone, laptop, tablet) which in turn communicates with the source Mac mini. I leave the Mac on at all times, and set it to restart once a day at 4am, and install any updates automatically. I upgraded the internal hard drive to solid state, and maxed up the ram. Solid!
roon is the best app/software for music that I have ever seen. Sonos has a great app. Roon is better. The fact that they are a software company is significant. They have to keep customers! A hardware makers app doesn't require the level of development and improvements that a software subscription will require. I challenge anyone to use Roon for a month and find better software.
i adore my dac. It is the PS Audio Perfect Wave Dac mkII with Bridge 2. Hard core stuff. $4800 new, can be found for way less of course now as it is showing it's age a little.
The Roon - PS Audio Bridge 2 combo is deadly. Bridge 2 is also available on newer PS Audio products. It allows one to bypass "playing" the music on the computer and instead the Bridge network card "plays" the music. ( need Bridge 2 for Roon). The connection is via Ethernet.
Feel free to call me, I'd be glad to share more details