Oddly enough, I am having the exact same problem. The difference is that I am using an external USB DAC (Fiio E07k) on a Mac Mini. I thought the DAC was the issue, but it is flawless on other computers. The Mini has a 180GB Intel SSD and the original 500GB HD acting as a fusion drive. I'm wondering if it could be something I else I have connected that is causing the issue.
8/27/13 at 4:48pm