Hmtc - you can get Toslink out of an AirPort express and with a good glass cable, it is not bad, but dont expect it to be as good as a CD transport. The chip and clock in the AE are just too jittery.
One solution to this is to use a Pace-Car reclocker from Empirical Audio. This allows you to drive the toslink from the AE to the PAce-Car and then an ultra-low jitter S/PDIF signal is driven out of the Pace-Car to your DAC. The jitter from the AE does not matter. You can even use a really cheap plastic Toslink cable. The Pace-Car output will outperform even the best transports. No mods to the AE are necessary. You can even select a variety of clocks, including the new Ultraclock.
Steve N.
Empirical Audio