The solution to the problem in connecting an external DAC to a MacBook Pro (Mac OS X) to pass the high resolution (hi rez) file at 24/96 audio out via the USB cable to the DAC:
"The trick is to set 24/96 for output, but 16/96 for input. It seems that OS X reserves the bandwidth on the UBS chain for input, even though the DAC will never use it"
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