Mini Mac, Sonos and NAS HELP

I was reading some of post here about using a Mini mac amd boy do I need some assistance! I currently have most of my CD's ripped into itunes in AIFF about 400mb (i have about another 300 Cd's to go and probably another 100 albums to digitize as well........I'm listening to then using a Sonos connect and ipad/ipone remotes with the Sonos app.
So far so good, but I can only play CD quality... I want to be able to play 24/96; I just bought a Wired 4 Sound Dac-1 it sounds great but I'm pulling the tracks from a PC w/vista using itunes....I'm out of hard drive space so considering adding a Mini Mac to store all my music and high rez files. This allows me to plug th Mini Mac directly into the Wired 4 sound dac with USB.
My other thought is to add a NAS so Sonos can pull the songs directly without my conmputer being on...I should of mentioned that i will have 2 set-ups the sonos for ambient whole house use and simplicity and the mac for my dedicated listening room...
Here's my current set-up:
Prima Luna Dialouge 2 intergrated
Wyred 4 Sound Dac-1
Golden Ear Triton Threes
Oppo 93
Sonos Connect/90
Any insight or advise would be appreciated!
Thanks
Robert