I have found that the USB DAC I am currently using (NAD M51) is not working properly with software using Core Audio such as Spotify or iTunes. The Bitperfect add on with iTunes is not working either. Audirvana+ using exclusive mode is still working although only on files with a bitrate of 96 kHz or less and there is something ever so slightly off about the sound. My B&W MM-1 seem to be working properly too. I now see that these issues along with my mouse not working have me understanding what beta really means. Be forewarned if you are using external audio gear.