I have been using the analog output from my Mac Pro into a Yamaha R-9. I connected the headphone output with a good quality cable to my receiver. Sound was good. I had no complaints. I've been looking for a DAC, but was hesitant to spend the bucks without knowing if there would be noticeable improvement. A few days ago my R-9 went KABLOOIE! The main fuse popped and I don't have time to troubleshoot it. So I replaced the R-9 with a spare Yamaha RX-V793. The 793 has digital inputs and I just happened to have an optical digital cable that fit my Mac Pro and the Yammie. Plug in the cable and change the audio output of the Mac Pro and I have music. I notice a marked improvement in SQ. The bass is punchier, the highs are brighter and crisper. Overall, the sound is very much better. I often wondered how well the DAC was in my 2009 Mac Pro, which is a 2 processor high end Mac often used for pro audio work. Now I know. The Mac Pro DAC is not nearly as good as the DAC in my Yammie.