Me thinks this could be a nice match with the PAW Gold. PAW Gold has a great DAC and line out. And it already has a superb DSP-based PMEQ so no reason to do the ADC>DAC internal conversion in the Shure amplifier if you want to tweak the sound.
Alas $3,000 is too rich for me right now. I would love to hear it though!
(The iPhone capability is interesting too. It would be nice to know more about the internal DAC chip.)
mmm.....+1 on the Paw Gold as a possible match-up with this Shure. It is an awesome DAP that packs quite a punch SQ-wise (including the line-out).