I'm using Mac OS X with Pure Music as the software player. Since Pure Music integrates with iTunes, you can use the "Remote" app for the iPod/iPad/iPhone and it works really well. You can browse through your library of artists, albums, songs and playlists etc from your mobile device.
Simple to setup. Setup iTunes with all your music and have your mobile device detected by iTunes (just install the app on your mobile device and it will search for a host when you add a Library).
That's what I use and I have no USB devices in the Mac Mini except for the DAC and have no display connected to the Mac Mini either, for a headless, optimal operation. All focus is on the sound quality and ease of operation.
Hope that helps.
Best,
Clayton