Suggestions on Better Server Setup than Mac Mini

@cdc2 .. many of us have dumped our computers for dedicated streamers. There are some very good options at every price point. IMO a streamer is a more elegant solution. After years with a Mac mini based audio system I bought a Bluesound Node 2. It’s been over a year now and I’m still very happy I went down this road.

I agree that dedicated server is more "elegant" solution, but Mac Mini, that I use, is not bad at all.  It is pleasure to use IMHO, at least for me, have very little software issues, is very secure and rock solid (in comparison to Windows).  I assume that USB on the Ultra Fi Dac is asynchronous.  In such case computer timing is not important and it can be used as home computer for other tasks at the same time.

Consider an RPI3 with a Digi hat to read the data from a NAS or USB hdd.  I assure you, it will sound better than a Mac Mini or USB out from a PC to your dac.  Use Rune, Moode or equivalent as software.  This is all very cheap but fantastic sound quality.  Rpi plug-n-play players are out there and they should play ALAC files.

wouldn't he have to move all files to a Pi?

BTW, OP how many files are involved?

Mac mini using iTunes sucks! When I switched to audirvana 2.x I switched from an iTunes library to the audirvana library, much better. 
I thought it was very good until I heard and evaluated dedicated music servers, and ended up getting the Auralic Aries, much better than the Mac mini / audirvana setup. I converted the Mac mini into an OS X server with 20TB of raid disk to store my audio music and other shared data. 
After the Aries, I moved up to the ps audio directstream with bridge ii and it is much better than the Auralic Aries and with my other dac using USB. The bridge ii uses the i2s interface internally between the bridge and dac