[Review] KingRex U-Craft(Y) cable and uPower PSU

KingRex U-Craft(Y) USB cable and uPower battery power supply

[KingRex U-Craft(Y) cable cable and upower PSU]

Super USB cable and battery power supply

Product name: KingRex U-Craft(Y) cable
Manufacturer: KingRex - Taiwan
Cost: 599 USD. (Currency conversion)
(YMMV)
Product name: KingRex uPower battery power supply
Cost 189 USD. (Currency conversion)
(YMMV)

Reviewer: Nick Whetstone - TNT UK
Reviewed: June, 2013

I think that it's fair to say that KingRex have established themselves as suppliers of good quality hi-fi components, not only sounding good, but looking great too. Like others, they have progressed from making class-T amplifiers to covering a range of amplification, both power and pre. It was a logical step to add a USB DAC to their range. In fact they now have a range of USB DACs, some of which we have reviewed here at TNT. The latest hi-res offering, the UD384 is their top-of-the range DAC and was reviewed by Andy Norman last year. To compliment that, KingRex have brought out two accessories: the U-Craft(Y) USB lead, and the uPower battery power supply.

The U-Craft(Y) cable gets the last part if its name from its configuration. It's a comparatively long cable (2 metres), and as cables go, quite heavy. I would guess that it is substantially shielded. It uses metal connectors, and another aluminium block where the two inputs join with the output. The review sample connectors/joiner were anodized in a red colour while the cable sheathing was an attractive blue (although I believe that other colours are available). All in all the cable looks substantial, and expensive. Looks aside, some thought has also been put into its design, and apart from the high quality connectors, the whole assembly is cryogenically treated to 'smooth out' the grain structure of the conductor material. And as usual, this KingRex product comes beautifully packaged.

Now while all this looks quite classy, in use, I wasn't quite so impressed! The cable used is rectangular in section meaning that it will only bend in one plain. As the cable is rather stiff to begin with, this makes it rather difficult to get it to go where you want it. And keeping in mind that most USB DAC's are small and lightweight, this isn't a marriage made in heaven.

Despite my reservations over the practicality of the U-Craft(Y), I installed it into my system. I only have the UC192 that I still can't get to work no matter how hard I try to get it installed. So (using an adaptor) I connected the U-Craft(Y) to an M2Tech USB DAC, and used a few different power sources. If you haven't got the idea of the U-Craft(Y) yet, let me explain that the two 'input' cables allow the signal and power to travel along them separately, rather than in close proximity along the same cable. This allows the user to connect the signal cable to the computer, and the power cable to a power source of their choice (that could even be a separate USB port on the host computer). But looking at the U-Craft(Y), one question came into my mind, ie having separated the signal and power lines, why does it then join them into one cable again for the last metre to the USB DAC? Surely the advantage gained in using the two input cables is (at least partially) lost by joining them back into one.

Despite my doubts, I carried on with the experiment first up trying this set up with a simple 5 volt plug-top PSU. The sound was slightly different compared to the supply coming from the computer but I couldn't decide which was best, or which I liked more. I then swapped the plug-top PSU for a Paul Hynes SR-5 and tried again. This time I felt that I slightly preferred the sound to that of the M2Tech DAC run through just a standard USB cable. At that stage it was time to take a look at the uPower battery supply that had been charging up overnight.

KingRex uPower battery power supply

Many people believe that their mains power supply is now so polluted, that the only way to get a 'pure' supply is to use batteries, and be isolated from the mains supply. For items that require comparatively low levels of power, batteries are quite practical. Not too long ago I reviewed a USB converter and DAC from Human Audio, and very much enjoyed the sound of that battery-powered set-up. USB DACs and converters require little power so batteries are ideal, and I have experimented with various batteries in the past. Arguably the best battery for this type of work is the Li-Ion type, and that's what is in the uPower . It comes with a wall-wart charger supplying 7.5 volts, and it has two outputs, one supplying 7.5 volts, and the other the 5 volt supply as used by most USB equipment. The batteries, and the recharging and regulating circuits are housed inside a smart metal housing 80mm wide, 95mm long, and 22 mm thick. The brushed aluminium finish is classy, and the whole unit feels reassuringly solid and well-made.

On one end of the uPower is a socket for the input supply (7.5v in) and next to that is located a switch that selects either charging mode, or DC out mode. On the other end is a USB socket for 5v out, and a round socket for 7.5v out. The 7.5 v in and out sockets are of a different size to prevent the user accidentally connecting them up the wrong way round; a nice touch. In between the output sockets sit two LEDs to show which mode (charging or supplying) is active.

With the U-Craft(Y) cable already in the system, I connected up the uPower module and sat back to listen. The results were consistent with my previous investigations into battery power. There is a 'magic' about the sound with batteries, relaxed, clear, detailed with an inky black background. The music sounded more emotive, and was very enjoyable to listen to. But it wasn't perfect for every type of music, and on rock music for instance, it could sound a little too laid-back, and I found myself wanting to put in the Paul Hynes SR-5. It really was a case of one supply being better for some types of music, and the other winning with other genres.

So where does this all leave us with the review of these two items? First the U-Craft(Y) cable. I did find it a little impractical to actually use. OK, if you don't review hi-fi, and don't mess around with your system much, you will probably install it once and leave it alone. Did it improve the sound quality on it's own (that is, simply taking the signal and power from the same computer)? I find the differences between USB cables to be minute anyway, and the best I could say about the U-Craft(Y) would be that it is one of the better USB cables. With a separate power source, when I compared it to the Elijah Audio cable that does the same job, I found that there wasn't any discernable improvement when using the U-Craft(Y) despite it costing considerably more.

Things are a little bit easier to judge with the uPower module. It's a very well made item, easy to use because you can simply switch between charging and powering the USB DAC. The sound it produced (with the 'right' type of music) was excellent, and as Li-Ion rechargeable power supplies go, it's as good as any that I have heard (with the bonus of a 7.5 volt output should you require one). So I would recommend the uPower but not really the U-Craft(Y) unless you have an all-KingRex system and want a matching USB lead. (or a USB cable with plenty of bling).

Manufacturer's reply

First is your question, "one question came into my mind, ie having separated the signal and power lines, why does it then join them into one cable again for the last metre to the USB DAC? Surely the advantage gained in using the two input cables is (at least partially) lost by joining them back into one"

As you can see, our Y cable is like this

[KingRex diagram of U-Craft(Y) cable.] You can see that two cables combine together into one by our aluminum case, and this case’s function is like a filter to eliminate noise and rearrange the signal, we eliminate the noise from PC to make sure that we get a clean data due to this case. Then we use U-Power to connect to UD384 to provide 7.5V by a small cord. We try our best to remove any possible distortion during the whole process, that’s why we call "Power for Silence" for this cable.

Basically, these USB cable are not very suitable for small and portable USB DAC, they are for Hi-End USB DAC, why?

The limitation performance of DAC.

Because what the USB cable bring is a "CLEAN SIGNAL", the signal needs to be interpreted by DAC, and maybe get a limitation due to the performance of DAC. For example, this cable is more expensive than some USB DAC, for a small DAC. It can meet its limitation easily, you can increase the performance by this Y cable, but you don’t think it’s worth for this increase.

It can elaborate a bigger and more expensive DAC much better than it was. For UD384, because it has U-power can supply pure battery power for use. It would be much better too.