HELP with MAC MINI and PS DIgital III DAC

New to this , so here goes-(and i looked for this question, couldn't find).
Have new MAc mini, just added PS Audio Digital III- now I cant play any of my HDTrack downloads- 9600?- Take it easy on the new guy- Using Itunes into Amarra Mini software--Any ideas?.also my $80 Rad-Shack works fine with this set up. Thank i advance-s