I read a review in Stereophile which highlights the following issue: as the AE doesn't have a local clock circuit, when the incoming data is interrupted, as it is when you change songs in iTunes, there is no longer a digital output to feed the DAC, which loses lock as a result. Not all DACs deal gracefully with the lost lock and are quick to unmute when the new song is sent to the AE thus the first seconds of a song might be cut off.
I intend to use a Cambridge Dac Magic with an Airport Express: do you know whether this DAC deals with this issue?
Thanks, js