
Black Holes and Revelations: KingRex UD384 DAC and UPower PSU
The new UD384 DAC from KingRex delivers music with an absolutely black background I have yet to hear from other DACs. From the first moment I tested the UD384, even with a humble HeadRoom Micro and Shure SE215 combo, I realized that this DAC has got the lowest noise level and the blackest background that I’ve heard in a while. I’ve listened to a lot of great DACs with black backgrounds, but they are not this black. The KingRex is so black, your monitor can’t reproduce it even if it was turned off.
The Black Background
Imagine an empty concert hall in an empty building in an empty town. The moment somebody walks in to that hall, you know that the sound of his steps is going to be very distinct, moderately loud, and crystal clear. If we were to take this guy and drop him in New York’s Fifth Avenue or Tokyo’s Shinjuku district, with thousands of other people walking on the same road, you can imagine that his footsteps will simply disappear, even if he tried stomping his feet twice as hard.
We’re talking about relative noise levels here. Another example is when you happen to be up at 1AM at night, when things are so quiet that you can hear the second ticking on the clock very clearly. If you turn off the A/C for a moment, close all doors and windows, and get under your blanket, then even the sound of your breath would suddenly sound very loud. It’s not because you’re breathing harder, rather because the relative noise level is so low.
This is what a black background is all about. When the relative noise level is so low, the slightest noise so clear and distinct, without having to boost treble levels. The result is crystal clear sound even at very low volume levels.
I’m totally in love with the KingRex, even not considering the superb 32/384 driverless USB capability. The sound is extremely natural, no treble boost, no fancy tricks, just simple pure black background. Vocals and instruments are incredibly distinct and real. There is no shrillness, no dryness, no nasty elements whatsoever in the sound. The tonality is quite dark, but then again there is no difficulties in seeing the details in the recordings because of the black background. Of course it’s recommended that the KingRex be paired with a good transparent amp like RSA’s Dark Star or Woo Audio’s WA5 so you can hear all that blackness in the soundscape. But even if you’re only using a relatively entry level amplifier like the HeadRoom Micro Amp or JDSLabs’ O2 amplifier, the blackness of the KingRex is still very evident.
USB to S/PDIF
I didn’t really test the UD384′s ability as a USB to S/PDIF converter, but my friend Drew immediately bought the UD384 and sold his Empirical Audio Offramp Turbo USB to S/PDIF after spending a few days with the KingRex. His comment was: “an incredibly black background”.
Minus the UPower
The Upower is a rechargeable, 2600mA battery pack designed to supply clean power to the UD384. But say your budget only allows for the UD384 without the UPower, what kind of a sound will you get? A weaker low bass is the first one I notice, though it still hits quite low. More subtle changes, however, includes a less distinct instrument presentation and body on the soundscape, as well as smeared transients though just a tiny bit. Without the UPower, the UD384 will still take on the DACPort LX any day of the week (not to mention the added 24/384 resolution and USB to S/PDIF converter function which the DACPort doesn’t come with), so this is still a very good DAC. But with the UPower, the UD384 suddenly is playing in a $1,000+ territory. Totally awesome stuff for the money.
I’m actually not such a big fan of the Ipod sized form factor. You have the USB cable coming in from one side and the RCA out from the other side. Then you have the power cable coming out from the Upower and into the UD384. Since this is a USB DAC, you’re bound to have it placed close to your laptop, and all that cables, especially the DC power cable that connects the UPower makes the KingRex pack looks like a messy piece of gear on your work desk. I would rather KingRex offer the whole package with the UPower in a one box package, perhaps a Schiit Asgard size enclosure, and even throw in a decent headphone out in the box as well. But regardless of how messy it is, still I’m using it every day of the week simply due to that blackhole-like dark background.If they had put the UD384 in a more convincing package, it probably can sell for a good $1,000 and still be a good buy at that price.
The UD384 is so amazing I’m intrigued to give their headphone amplifier a try. Who knows, it may be another winner.
Gear used for review:
MacBook Air, Audirvana+, Fidelia, Amarra, Ray Samuels Audio Dark Star, Woo Audio WA5, Minute 45, numerous headphones and other amplifiers.
The UD384 outputs both digital and analog signals, making it both a potent DAC and USB to S/PDIF converter.
When it's being charged, the UPower doesn't power the UD384, so it's essentially an on/off switch. Off = recharge, on = no recharge.


The Upower outputs 7.5V for the UD384, and 5V through USB for any other devices you may have.
You get one wall wart for each of the UD384 and UPower units. It is used either for powering the UD384 and/or for charging the UPower battery pack.
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