Good afternoon, Matt. If your optical out sounded a bit "cloudy," you might want to check your MIDI setting to see that they match your medium you're playing. On every restart in the Mac OS, MIDI setup defaults to 96/24 which controls the iTunes playback settings. Assuming you're playing 44/16 files, if you've not reset MIDI to 44/16, iTunes will "upsample" the files to 96/24, which will then be resampled down by your DAC to 44/16. Repeated resampling has been reported to have an audible effect on the sound. Just my 2 cents, but might be worth a try. Cordially,