You're making way too much of Harley's statement. I just don't think you can generalize about what connection is better across different systems with different digital components. The exact implementation of the interfaces can easily override any theoretical considerations. If you setup allows multiple signal paths, then take the time to try each one and determine which one you prefer.
Server to DAC connection
Robert Harley recently reviewed the top Aurender server, which offers several choices of connection to a DAC. He preferred USB via a Berkeley Alpha USB converter. By adding a cable and complicated piece of hardware, this seems to go against the 'simpler is better' philosophy. But, I wonder if there might be an overall gain with the Berkeley. I have the Aurender N10, and I'm currently using the SPDIF connection, as my DAC does not have a USB input. I'm thinking of trying the Berkeley Alpha USB. Has anyone else compared the Berkeley to AES or SPDIF? For those with a USB DAC, how does the Berkeley compare to a direct USB connection?