The UD-01, KingRex’s mid-priced USB digital audio converter, offers a sizeable leap in sound quality over a PC’s on-board sound solution, but you’ll need an equally high-quality system to take advantage of it.

In the world of audio, the personal computer is something of a black sheep. Long reviled by audiophiles as a source lossy, low-quality music fed out through noisy internal circuitry to cheap speakers, the PC is starting to slowly make itself heard as a legitimate digital audio hub.

Central to the process of outputting audio is a computer’s sound card. It’s the device that turns a digital avalanche of ones and zeros into an analog electrical signal that goes on to be amplified and blasted out through speakers. The problem with sound cards is that, by their very nature, they’re sensitive to electrical noise. The two simple ways around this are either to lower the card’s sensitivity, to block background noise — compromising sound quality — or to use higher quality components — raising prices and not fixing the problem entirely.

The only sure-fire way to eliminate digital noise is to physically separate the sound card from the computer enclosure. That’s the KingRex UD-01’s modus operandi — attached via a USB cable to the PC, it sits in its own enclosure and uses high-quality components to decode audio signals.

Working natively on both Windows and Macintosh systems, the UD-01 is simple to set up. A power pack is supplied as well as a USB cord, which uses a traditional USB-B plug to connect to the unit. Output is through stereo analog RCA ports, so it’s perfect to connect to a dedicated amplifier. Chances are that if you’re using anything that requires another type of connector (like entry-level PC speakers using a 3.5mm headphone jack, for example) you won’t benefit too much from the UD-01.

For our testing, we compared the UD-01 to the on-board sound from a Gigabyte P35 DS4 motherboard, as well as a Creative Xmod and Sound Blaster X-Fi Surround 5.1. The UD-01 is only capable of stereo output, so if you need surround sound the other systems' various digital and analog outputs might suit you more.

To establish digital noise levels we conducted a simple test. With the system connected to our test setup of a KingRex T20 amplifier and JohnBlue JB3 speakers, we cranked volume levels to max and listened for higher frequency hissing. Using the on-board sound system it was noticeably audible; it was less so with the consumer-level external solutions. With the UD-01 connected, however, we were pleasantly surprised by the lack of any audible hissing or interference — a testament to the high quality of the internal circuitry in the device.

Sound quality was stellar. Background noise aside, we did notice a slight difference in the timbre and clarity of sound with the different systems. The UD-01 reigned supreme throughout our test, with a more expansive sound range and a slightly warm signature.

The only problem with picking up a quality DAC like the UD-01 is that you’ll need to have equally high-quality components to be able to take advantage of the additional clarity and sound quality. If you’re currently getting by with a high-end system directly connected to your PC, consider this product carefully.