What ever the case is the wadia i170 or the ipod it still has a very high measured jitter from the digital output
This may not be a reflection purely on Wadia...it seems that ALL digital interfaces suffer from it to some greater or lesser degree. This is WHY it is so important to use a DAC which has some effort made at reducing jitter other than the old and to basic PLL method (various schemes exist form buffering to asynchronous upsampling etc. etc, - pick your posion)