streaming audio data file through USB is not as simple as thought, as the PC clock and your network DAC clock has to be synchronize else you may have jitter data error. See the attachment file on how they implement USB audio streaming. Thus if you add any external clock it will improve sound quality, or a better USB cable that reduce interference noise also improve sound quality.
However if audio streaming is through a true asynchronous transmission, then clock timing is not that critical for data streaming. Guess they choose the easy way for consumer but not necessary best for audio.
"In telecommunications, asynchronous communication is transmission of data, generally without the use of an external clock signal, where data can be transmitted intermittently rather than in a steady stream.[1] Any timing required to recover data from the communication symbols is encoded within the symbols. The most significant aspect of asynchronous communications is that data is not transmitted at regular intervals, thus making possible variable bit rate, and that the transmitter and receiver clock generators do not have to be exactly synchronized all the time."
Absolutely true. Clock precision plays a key role in DAC operation. Computer is designed to tolerate high jitter transfer, but ensure data integrity. However, this is bad for audio.
IMHO, products with match high-precision clocks, such as Auralic Aries media bridge and Auralic VEGA DAC whosie femoto clocks lock onto each other, or integrated server/NAS+DAC such as Aurender A10, are good designs because they solve the clock issue.
