KingRex UD-01 USB DAC
KingRex UD-01 digital to analogue converter
It is a fact today that many audiophiles are now choosing to use their home computer as their music source, but the computer environment is very noisy and not ideal, hence KingRex came up with the solution of this off board sound card DAC that will give a very impressive sound boost for very little outlay.
The very stylish UD-01, is KingRexs entry level
USB digital audio converter, it offers a dramatic boost in sound quality
over your PC's on-board sound card, this is all good news for the
audiophile that uses a basic PC audio set up. KingRex have the solution
for you with this DAC, so good in fact that you'll need an equally
high-quality system to take advantage of it.
Central to the process of outputting audio is a computers 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 cards sensitivity, to block background noise — compromising sound quality — or to use higher quality components — raising prices and not fixing the problem entirely.
The best cure for this dilemma is to eliminate digital noise is to physically separate the sound card from the computer enclosure and t's very noisy environment. 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 very high-quality audiophile quality components to decode audio signals.
The KingRex UD-10 works on both Windows
and Macintosh systems, the KingRex UD-01 is extremly simple
to set up. A 12V 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 such as the KingRex T20. 
The KingRex UD-01 is of better quality than the onboard DAC found in the T-20U amplifier. Also you can tweak the UD-01 to suit your tastes by easily swapping over the OP amps.
Its strongly musical 'non-digital-sounding' presentation is largely derived from the Burr-Brown OPA2604 which acts as an output stage preamp removing digital nasties and smoothly sculpting the analogue stream. The primary chip is the Burr-Brown PCB2702E mated with a large internal buffer for audio packet storage.
Please contact us here at Eden Audio, we are here to help you make the right choice, we have these units on dem for you to listen to and enjoy.
A few review snippets
"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.
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.
To establish digital noise levels we conducted a simple test. With the system connected to our test setup of a KingRex amplifier and JohnBlue 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." - Good Gear Guide
"If I was beginning to think that USB DAC's were not for me as they sounded a bit 'light', the KingRex changed that idea straight away. But it's not just in the bass department that it works well, it's very impressive in all departments.
The sound is a long way from the old 'digital sound' that was associated with many CDPs. I won't say it sounds like a turntable, but you would have to be very fussy to complain about it sounding 'digital'. Like the SuperPro, the sound stage is massive, and there is great detail that brings out the ambience on certain recordings. The amount of detail is fantastic! I don't recall hearing the Q -sound effects on 'Amused to Death' (Roger Walters) quite so clearly, and as 'detached' from the speakers. The music just flows from the speakers, helping you forget the equipment and enjoy the performance. The balance is very good with plenty of bass and a good top-end. No need to 'tune' your system to fit the UD-01 in! Everything that I played through the UD-01 sounded great. And it didn't get tiring with extended auditioning.
I've read that some people don't rate the UD-01 very highly when powered from the wallwart PSU. However I was still quite impressed, possibly due to running the whole system through a very good power conditioner. I've found in the past that the cheaper wallwart PSU's (particularly the switched-mode type) can be affected by how good (or bad) the mains supply is. Unfortunately, I didn't come across the wallwart comments until after returning the UD-01 so couldn't listen without the conditioner.
The obvious next step was adding in the KingRex power supply.
The price of the PSU at around 165 UK pounds may cause some to ask if it is worth the extra outlay, given that it costs more than the DAC itself. I've had similar questions about power supplies for the Logitech SB3 but the bottom line is, power supply quality is absolutely crucial to sound quality, and good power supplies are not cheap. In this case, the addition of the power supply to the UD-01 clearly makes an improvement. Macro detail is increased and the bass gets tighter and a little deeper.
The next step was to try Item Audio's 'SE' version of the UD-01. Item have replaced both the opamps in the UD-01 after auditioning as many opamps, and combination of opamps, that they could get their hands on. Their 'winning' recipe was to use two pairs of OPA627 opamps (on adaptor boards) in place of the OPA2604 (not a great opamp in my experience), and the TL072. And this is clearly an improvement on the stock configuration, sounding better in almost every department. It simply sounds more sophisticated than the stock UD-01.
USB may not be the best way of getting music from a computer to a hi-fi system (Firewire is reputed to be better) but what you can get now, with items like the KingRex UD-01, and (to a lesser degree) the Devilsound, is a level of performance that is on par with CDP/DAC's costing well over a 1000 UKP.
And I suspect that even those with very expensive CDP/DAC's would be tempted to buy something like the UD-01 'SE'/PSU/Polestar cable.
OK, you can tell that the KingRex UD-01 was my favourite out of the USB DACs tested here. More accurately, I should say that the UD-01 'SE' was my favourite." - Nick Whetstone, TNT Audio
This is another review from the very popular head fi forum, he says.....
With the PSU, the KingRex UD-01 was actually pretty special - it was a big improvement over the USB DAC built into the Sweet-2, and much better than the UD-01 with the wall wart. MUCH better. With the PSU, The UD-01 provided a smooth, transparent, highly enjoyable sound. I was very impressed. Aside from the fantastic but very expensive RedWineAudio Isabella DAC, this is the best sound I personally have had coming directly from my PC. The UD-01, with the PSU, really doesn't have a "sound" which is a GOOD thing - it simply provided a very transparent hand-off from the hard drive to the Amplifier. And that is the nicest thing someone can ever say about a DAC.
I have felt many USB DACs were very grainy sounding, and were NOT transparent. Not so the UD-01 with PSU. The combination sounds excellent. I cannot recommend the UD-01 alone with just the wall-wart. However, the UD-01 with PSU gets an enthusiastic recommendation. It also reminds me just how important a good power supply is!
Bundle offers from eden audio!
KingRex UD-01 DAC + PSU 328€uros
KingRex UD-01 DAC + PSU Oyaide NEO USB cable 377€uros
KingRex UD-01 DAC + PSU Oyaide NEO USB cable John Blue JB3 727€uros
Please click here to purchase KingRex