X26Pro is a delta/sigma dac which - all other aspects of the device being equal - is the technically superior method of conversion.
R2R dacs tend to sound softer, less accurate, even though I think the R26Pro has a decent analogue stage. Also I haven't seen any information that leads me to believe it corrects for the low level linearity issues that discrete ladders suffer from (accuracy of the resistors for is a massive challenge for correct conversion of small signals).
I know many people will disagree with the brief dismissal of R2R