I recently bought a new 2012 i5 mac mini and added 16GB of memory to use as a music server with Audirvana 2.0.6. I unmounted the hdd and have the operating system on a 32 GB SD card. I run it headless via an ethernet cable from my 2009 macbook. The music files are on a 2TB external usb drive connected to the macbook.
I am probably going to modify the power supply and use an external Linear Power Supply to further reduce noise in the mini.
This set up is IMHO as good as systems that I have heard that cost 10x as much. Computer audio is the way to go. Oh, I am currently using an Emotiva XDA-2 DAC in conjunction with a NuForce J192 usb-spdif converter but I am waiting for a Geek Pulse to arrive once they get all the other crowd-fund backer's units
The computer audiophile rabbit hole is DEEP, endlessly deep, and you can find it by googling computer audiophile. Just sayin'.