I just picked up the Xduoo XD-05 from Massdrop a month ago. I think you can find them on Amazon for $170 ... man was I impressed. I ran HD tracks from my Samsung phone to the XD-05 via the OTG cable (digital to the DAC then the headphone amp). Tested the setup out with my Sennheiser HD-650's and Grado SR-60's. Holy crap! Well worth the cost ...