Thanks for the suggestion. So the audible diffrences between DX and these models could be very subtle??  

Hello.    My devices are AKG K612 pro(K601), Objective2 amp, a desktop PC.     I've narrowed down my DAC choices to these 3 models.   1. Odac ( $150 new)    2. Asus xonar essence ST ($140 used)     3. Audioquest dragonfly ($200 new)      Which one do you think I shoud get?    I...