Douk Audio K5 USB DAC & Headphone Amp: Featuring USB and SPDIF optical inputs, as well as optical, RCA and 6.35/3.5mm jack outputs, the K5 serves as a high-performance headphone amplifier, a USB DAC, a preamp, but also a USB to optical converter to transmit the high-quality audio from the computer to those audio devices only with SPDIF digital input such as CD players, amplifiers and active speakers etc.
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