REVIEW: KingRex USB DAC UD-01 and PSU

[Skylab]

I received a request from the manufacturer of this product to review it. The UD-01 is a little bigger than a portable headphone amp, and is built around the Burr Brown PCM 2702E DAC chip with a Burr-Brown OPA2604 low pass filter as the output stage. It comes with a wall-wart power supply, but there is an option for a much upgraded power supply, about which, more later.

Pics:

I reviewed the KingRex products being fed Apple Lossless files from iTunes via the USB output of my Dell XPS Core 2 Duo laptop, and with the DAC in turn feeding my Decware CSP-2 headphone amp. I used mostly my Beyerdynamic DT990/600, but also used my JVC RX900’s.

OK, I will admit it: I really was not excited about reviewing this product. I’m just not all that enthusiastic about the product category of stand-alone USB DACs. The UD-01 costs $209 with the wall-wart power supply - $340 when combined with the enhanced PSU. I have a TNS Sweet-2 that is a USB DAC, tubes headphone and speaker amp with remote control that I bought for $299! And the USB DAC in that sounds pretty good.

To make matters worse, the sound of the UD-01 with the wall-wart supply was nothing special. Competent, acceptable, and better than the line out of my laptop, yes. But it was also slightly grainy, slightly rough, and slightly aggressive sounding. I wasn’t in love. I was ready to give up.

I gave KingRex some comments, and they sent me their PSU unit to use in the review. And here I encountered a new problem – the PSU was sent to be without fuses installed, and arced and shut down when I went to plug it in. Bummer.

Undeterred, KingRex sent me some fuses. And so I installed them, which was actually no easy trick, as one is on the circuit board inside of the extremely well built PSU which requires both a Phillips X and Allen wrench to get open! I was really just about ready to give up.

But I am glad I didn’t. 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!

 

[kydsid]

Awesome. I have had this DAC as part of my travelling rig for a while. I wasn't aware there was a PSU.

I have the same conclussions you did with the dac and wall wart. Certainly better than the computer alone and the size and price is what sold it for travelling purposes. I will say that mine mellowed a bit with age and use in it's aggresiveness. That being said my brand new DacMagic is beyond it still.

I will have to give this PSU a try. Any chance they will send one to me to tryout.

lol

 

[dwong]

Nice review! Seems a bit pricey at $340, and if you need a bulky PSU like that for it to sound best, I would think it would just negate its use as a portable DAC.

 

[kydsid]

I don't think it was intended to be portable. It is small yes. But it takes a wall wart and only has RCA out.

Also keep in mind that all the opamps are socketed allowing you to change at your preference. And the unit can be found at audiomagues for $177.

PS: Skylab - What PSU did they send to you? I cannot find any info on their website about a seperate PSU.

 

[apatN]

Thanks for your work and contribution. Seems a bit too pricey. Might as well get the Musical Fidelity V-DAC instead.

 

[Skylab]

Quote:

Originally Posted by kydsid /img/forum/go_quote.gif I don't think it was intended to be portable. It is small yes. But it takes a wall wart and only has RCA out. Also keep in mind that all the opamps are socketed allowing you to change at your preference. And the unit can be found at audiomagues for $177. PS: Skylab - What PSU did they send to you? I cannot find any info on their website about a seperate PSU.

From that same site, regarding the PSU:

Audiomagus - high end not high priced audio products

I cannot vouch for that seller - never used them, but that is where I got the pricing.

 

[Bones13]

I bought an amp from Audiomagus. It is the Mardis V3.0, with a fair amout of their custom work. I did have to send it back for some channel balancing, but they handled it fine, and the amp is lovely now. Nice group of guys that sell pretty good imported gear, and their tweaked gear is really special, despite having pretty good prices. They were easy to work with, answered emails etc.

 

[Townyj]

Ive been wondering about this PSU for awhile.... Reading that it does wonders to the UD-01. May have to look into it

 

[poo]

I've been using the T20U with external power supply (the same used in your review) for over 2 years now with a pair of Quad 12L.

I have found it to be an excellent device worth many times its cost. The DAC provides clean sound and the amplifier does a fine job of driving the Quads. Would love a little remote, but regardless I am a very satisfied customer.

 

[hubsand]

Were you really using those cables for the test?!

 

[hubsand]

Quote:

Originally Posted by kydsid /img/forum/go_quote.gif Awesome. I have had this DAC as part of my travelling rig for a while. I wasn't aware there was a PSU. I have the same conclussions you did with the dac and wall wart. Certainly better than the computer alone and the size and price is what sold it for travelling purposes. I will say that mine mellowed a bit with age and use in it's aggresiveness. That being said my brand new DacMagic is beyond it still. I will have to give this PSU a try. Any chance they will send one to me to tryout. lol

A couple of us auditioned a UD-01 with the PSU just after the DacMagic came out and the KingRex was much better in every way (with 16 bit files, at least). It's just a different animal with the PSU.

 

[Skylab]

Quote:

Originally Posted by hubsand /img/forum/go_quote.gif Were you really using those cables for the test?!

Ha! No, just for burn in (and unfortunately, photography

).

For auditioning I used Audioquest IC's. They are nothing crazy-special, but I don't see using $300 interconnects with a $200 DAC.

 

[Skylab]

Quote:

Originally Posted by hubsand /img/forum/go_quote.gif A couple of us auditioned a UD-01 with the PSU just after the DacMagic came out and the KingRex was much better in every way (with 16 bit files, at least). It's just a different animal with the PSU.

It really is, isn't it? Surprising, perhaps, but true.

 

[hubsand]

Fair enough. Though I guess with the PSU, it's a much more expensive DAC. I notice that there are already some combination offers pairing the KingRex DAC and PSU. I got mine from there and just tried it with the CryoParts USB cable which for some reason manages to sound clearly a notch above the standard 99p ripcord. Then again, it's a lot more expensive . . . back to what you were saying about cables!

 

[hubsand]

It's all well documented how much difference a good clean PSU makes to amplifiers (which I suppose is why the PSU was designed for their T20), but it's shocking to see how much difference it makes to this DAC. I also tried the same PSU with a Monica 2 and 3 and a couple of other low-end DACs. It made them all better, but none were transformed to the same extent. Presumably it goes to show how good the UD-01 is - or how much it's held back by the switch mode stock PSU.