We came across Kingrex's product while searching for a power supply upgrade for another manufacturer's DAC. Kingrex's PSU MKII proved to be one of the most cost effective upgrade we can recommend to a USB or wall wart powered DACs. We weren't the only one, but also numerous favorable feedback from various internet forums.
At the time Kingrex also makes a very nifty USB to SPDIF converter (they prefer to call it DDCs - digital to digital converters) called the UC192 (still in the line up, firmware upgraded to 32/384 conversion through i2s). We were so impressed with the power supply that we contacted Kingrex for a review unit. Kingrex informed us that they were about to launch a new model, which is not only a DDC, but also a high resolution 32/384 capable DAC/DDC plus a dedicated power battery supply designed for it. So we decided to wait for the UD-384 and U-Power which are the subjects of our review here.
Dynamic Duo
The combo arrived and we are quite surprised to see how small they are. They are light (less than 200g each) and compact, each about eleven cm long, and made of anodized extruded aluminum. They are quite well made but rather light and 'casual' looking. The U-Power is optional ($179) and in such case the UD384 would be powered by a supplied generic 7.5v wall wart. You can then choose from two upgrade path - the U-Power, or the more expensive AC-powered PSU MkII, please do note that you will have to specified a 7.5v version for the latter. For those of you who are suspicious of how good clean power can do to the sound, you'll be surprised that for hifi equipment, a significant percentage of the overall sound quality depends on that. Basically you are what you eat.
The combo arrived and we are quite surprised to see how small they are. They are light (less than 200g each) and compact, each about eleven cm long, and made of anodized extruded aluminum. They are quite well made but rather light and 'casual' looking. The U-Power is optional ($179) and in such case the UD384 would be powered by a supplied generic 7.5v wall wart. You can then choose from two upgrade path - the U-Power, or the more expensive AC-powered PSU MkII, please do note that you will have to specified a 7.5v version for the latter. For those of you who are suspicious of how good clean power can do to the sound, you'll be surprised that for hifi equipment, a significant percentage of the overall sound quality depends on that. Basically you are what you eat.
The unique thing about the UD-384 (US$479) is that it is both a DAC and a USB to SPDIF converter. We think this is such a nifty idea since you may, in the future, want to upgrade to a more extravagant DAC which you can still use the unit's asynchronous USB conversion that works up to 24bit/192kHz (SPDIF's technical limitations prevents the UD-384 to output higher than 192kHz). There are however no other digital inputs except USB. Drivers are supplied for Windows, there are no drivers necessary for Mac users.
The U-Power internals are also well thought-out. There are two 3.7v Li-ion batteries supplying 2600mAh of power. Charging is done through the supplied wall wart, and a circuit disconnects noisy A/C supply during battery playback. There's also a USB power port on the U-Power, I was hoping this is a power input but it actually is an output which can feed 5v power to a USB device.
They rock!
How does it sound? In one word - impressive. If you do a blind test having your typical big shiny aluminum box high end DAC side by side and ask your friends to guess, they would surely have it wrong. What we are most surprised by is its ability to handle slam and weight. The resolution is also amazing with air and openness rivaling the best out there, both with normal 44.1k CD rips and native high resolution files. Having said that, this is not a DAC for detail freaks. It doesn't draw you into the minute details like some of the DACs do, but more the coherent message. It just excels on tempo and energy and plainly "boogie". Soundstage is spacious, precise and wide, with images being so stable you can reach out and touch them. Although the stage is not as deep as some, but enough for you to work out the layers without feeling a wee bit of congestion. This is not a hifi-sounding DAC, it is ever so smooth without edginess of lesser DACs. Pace Rhythm and Timing are excellent breathing down the neck of much more expensive units. The mid bass is tight but never bloated, which puts it on the clean and taught side of the scale as opposed to romantic and lush tendencies of tube peers.
Most of our listening was with the supplied U-Power unit. However, we did have on hand the dearer Kingrex PSU MkII for comparisons. The differences were quite small. You will have a slight better macro dynamic with music with big dynamic range swings, but the all else were excellent as it is. The synergies of the two units are there and is highly recommended you get the UD-384 and U-Power as a combo.
Conclusion
Once in a while you come across a product that are so deceptive simple in appearances. These little boxes proved to be so much for the price. If you are new to computer audio and do not want to spend a fortune on state-of-the-art converter or DAC, the UD-384 is a great future-proof USB/SPDIF converter with a superb DAC to boot. We think the UD combo is the best sounding DAC we have heard so far in its price range.
