Hi-Res Amp DDA-DAC1U is a USB DAC and headphone amplifier corresponding to the playback of high-resolution sound source. We realized in a simple system the music playback from a high-resolution sound source in high-definition sound quality. We aimed at a design, which is expected to be high-quality sound, while everybody is looking at its appearance. We considered ease of use and made frequently used volume button the central design icon. In addition, seamless aluminum housing deadens excess vibration.