Darn!... So perfect! A S/PDIF input would really seal the deal here in making this worthwhile to getting over an Android Smartphone + a portable USB DAC/Amp. Since either way you'd be carrying your phone around + an extra device, why not simply use your phone as what stores the media and a cheaper (perhaps even better sounding) USB DAC/Amp of choice (like the E18 for instance precisely for this purpose)?
Adding a S/PDIF input would truly give this device something which no phone would have and would increase it's application significantly, making it worthwhile to carry around and/or buy instead of simply a portable DAC/Amp.
The only things which the X5 currently holds over the alternative seems to be the rare cases where you might want to daisy chain another DAC through S/PDIF, for the small market of users who may actually utilize the DSD functionality, and/or if you really need more than 128GB of space for portable use... Am I missing what the reason would otherwise be to invest in this DAP?
Excellent sound quality without external amplification at a very reasonable price? Just throwing that out there as something that some of us might find relevant as a reason to "invest in this DAP".