Sunrise Ray DA-P1 Headphone amplifier & DAC @ techPowerUp
 

Sunrise Audio's newest DAC / amp gets put to the test. The Ray DA-P1 is built with Android devices in mind and works with devices that feature USB Audio in the kernel. It is also a very capable small form factor DAC / amp that won't give you any problems with Windows.

http://www.techpowerup.com/reviews/Sunrise/Ray_DA-P1/