Testing 18.0.178 on both Mac Mini and MacBook Pro with 10.8.3 OS. Each machine has 16 GB RAM. Identical results on both computers: Media Center works well with all tested DAC's: Wadia model 121 DAC, Ayre QB-9, Cambridge Audio DacMagic and many others. System plays .m4a and FLAC from 44k up to 192k with no problems on all DACs. However, using RME Babyface which has both ADC & DAC, same problem as earlier, when 'Play' is executed with all variations of sample rate and file format, output audio consists of a burst of white noise for about 1 second then Media Center exits memory. I tried all three choices of 'Buffer size' and tried various 'Channel offset' values to no avail. If there is any other configuration that I may test, I will be happy to help. I have access to a wide variety of DAC's and a broad range of content. Thanks.