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Definition: USB DAC

(USB Digital-to-Analog-Converter) A D/A converter (DAC) that connects to a computer via the USB port for music playback. The USB DAC has become popular because people like to organize their music on the computer with software such as iTunes and Windows Media Center and play it on their stereo system.

Digital to Analog
The USB DAC converts digital audio signals from the computer to analog signals for the amplifiers and speakers. Although an analog connection can be made via the outputs on the computer's sound card, purists maintain that external USB DACs provide superior conversion and better sound quality. In addition, an external DAC may be the only way to play high-resolution music files that are not supported by the computer's hardware (see high-resolution audio).

USB DACs are available in a wide price range from a couple hundred dollars to several thousand. The 2010 CES Las Vegas High-End Audio exhibition showcased a hand-crafted USB DAC for $37,000. See headphone amp, D/A preamp, D/A converter and CES.

A USB DAC in Action
In this example, the Audirvana app in a Mac is playing high-res digital audio files from HDtracks, and the Meridian Audio Explorer DAC is converting them to analog for the receiver's AUX inputs. The three LEDs denote the sampling rate. For more information, visit www.meridian-audio.com, www.audirvana.com and www.hdtracks.com.

An Audiophile USB DAC
Ayre was the first to offer an "asynchronous USB DAC," which puts the master clock in the DAC to regulate the data transfer. This Ayre QB-9 is a high-end unit with XLR audio outputs (arrows). The 44 refers to the 44.1 kHz CD standard sampling rate. (Images courtesy of Ayre Acoustics, Inc., www.ayre.com)

A USB DAC and More
The inputs on Oppo's Sonica DAC include digital audio from a computer's USB port as these examples in the user guide illustrate. For more information, visit www.oppodigital.com.