If music server is your future, then you should absolutely consider the Wavelength asynchronous USB DACs. They get around jitter (though not entirely) by having the DAC clock manage the audio stream instead of the computer - which is much less reliable.
Of all the computer based DACs I've listened to and owned, it is far and away the smoothest to my ears.
Of all the computer based DACs I've listened to and owned, it is far and away the smoothest to my ears.