UHA-6S MKII Portable USB DAC and Headphone Amplifier - Black Four types of input: USB, optical, digital coaxial, and analog. Connect to just about any analog or digital music source out there. Low-noise and low-distortion amplifier output. Drives most types of headphones and earphones, from low-impedance IEMs to high-impedance cans. Works with Mac, PC, iOS, and Android. Stream digital audio directly from your computer or compatible mobile device. Small, lightweight, and portable. Internal battery charges over USB. Charging can be disabled for operation from the battery only. 30-day audition period and 2-year warranty. If youre not completely satisfied with the UHA-6S MKII, just send it back for a refund.