The easiest way to get great SQ is to use an Oct. 2009 Mac mini, because it has external power supply that can be upgraded to a good linear supply. This make a big difference in SQ. To do this on a newer mini, you will need to pay someone to mod the mini.
The 2009 also takes 16gigs DRAM and it is a good idea to replaced the HD with a SSD. See this for more details:
http://www.empiricalaudio.com/computer-audio/recommended-systems
The best power supply for the mini is a paulhynesdesign.com SR7-18.5 or SR5-18.5.
Steve N.
Empirical Audio
The 2009 also takes 16gigs DRAM and it is a good idea to replaced the HD with a SSD. See this for more details:
http://www.empiricalaudio.com/computer-audio/recommended-systems
The best power supply for the mini is a paulhynesdesign.com SR7-18.5 or SR5-18.5.
Steve N.
Empirical Audio