This is the current top of the line USB cable from Audioquest, featuring solid Perfect Surface Silver conductors and the mysterious 72V Dielectric-Bias System. This being a serious cable, my first thought was: how would it compare to the KingRex uArt?
The Audioquest Diamond was brought in to be reviewed in combination with the Audio Aan Zee Ultra Flow Music Server but I couldn't help my curiosity and compared the cable with 2 other cables using 3 different USB DACs. As an added bonus, the minuscule Audioquest DragonFly USB DAC was also brought in to offer some perspective, but I'll report about that in a separate review.
As always, all units and cables were well warmed up and ran in and circumstances (placement of the unit, position in power extensionblock, phase, powercable used, interlinks used, input on the preamp, volume level etc) were kept as close as possible amongst comparisons.
iTunes most recent version used with default settings, no plugins
PureMusic and BitPerfect were also tried but this review focuses on iTunes in native form.
Cardas Hexlink Golden 5C XLR (DragonFly and PWD MKII)
Cardas Hexlink 5C cinch (V-Dac and UD384)
Comparisons using the Musical Fidelity V-DAC
First up was the standard no-name USB 2.0 cable, connected to the Musical Fidelity V-DAC. This was a familiar sound: a bit thin and light, but very open and airy and not at all bad. But for me it was clear that this was computer-sound. There was no fooling me that there was no computer at work, evident from an electronic, synthetic signature and a small soundstage that stuck to the speakers both horizontally and laterally.
Then the standard USB cable was swapped for the KingRex uArt. Boy what a difference: much bigger soundstage, much more beefy sound with more solid, fuller bass and a much more acoustical presence. Treble however was slightly less airy and a little drier. Overall though this was much better and clearly much less computer-esque.
Finally the Audioquest Diamond was connected. It is very different from the KingRex: more open and airy, cleaner, thinner in the bass and with quite a smaller soundstage. Seen this way it more closely resembles the standard cable than the KingRex and yet there was this difficul-to-put-a-finger-on rightness to the sound. This was a sound that you can quickly come to terms with. It wasn't shouting out, but the longer I listened the more it sank in: this cable just sounds right. There is no artifice to it and none of the emptyness that the standard cable has. Between the KingRex and the Diamond I'd say it is a tie. Both perform very well, but in different directions. The KingRex has more colour and acoustical fulness; the Diamond has better resolution and coherence and more open, more fluid treble. The choice will depend on the system used, and of course, taste.
What is evident is that a good USB cable can significantly upgrade a USB DAC. Silly as it sounds, even a cable costing more than the DAC still seems a worthwile investment to me if the end result is this good.
Comparisons using the KingRex UD384
The same cablerounds were performed using the KingRex UD384 DAC and the differences among them were consistent, however, the KingRex sounded best with its stablemate cable. The no name cable was clearly below par and the Diamond made it sound a little dull. Mind you this isn't the Audioquest's fault, rather the UD384 DAC which is really meant as a USB-SPDIF interface with a DAC thrown in. The UD384 as a DAC sounds ordinary and the Diamond does nothing to conceil this.
Comparisons using the PS Audio PWD MKII
You'd be forgiven to think that the PWD, with its built-in twin digital lense, would be immune to USB cables. Alas, it isn't. The differences between cables are just as clearly audible as with the cheaper dacs. The standard USB cable this time sounded fine. Already the soundstage was bigger and deeper than with any of the above combinations. Also the bass was just KING: solid, deep, visceral, articulate. I make no excuses for loving the PWD's bass qualities, that are very akin to the typical Wadia sound. Speaking of which, another Wadia quality is acoustical reality. Here, too, the PWD excells. Even with a standard cable. But then the swapping started.
First up was the KingRex. Yup, once again there was a deeper, fuller, more colourful sound that had even greater acoustical believability. Suspension of disbelief (it is not a computer) was already there using the standard cable, but now it was almost like listening to a Wadia CD player. Almost that is, because the treble was just a bit coarse and lacked some air. Strangely, the standard USB cable had more air!
Naturally this called for the Diamond and indeed it provided the same amount of air as the default cable, but with better acoustical qualities and overall more coherence and better low level detailing. The standard cable sounds a bit empty by comparison and there was no going back.
Overall I think that I prefer the KingRex for its larger, more 3D soundstaging, but it depends on the music played. I also like the Diamond a lot for its capability increasing the PWD's apparent resolution and treble extension. At this stage I haven't made up my mind just yet as to which is better. The KingRex increases on the PWD's inherent qualities yet adds to its weaknesses by having low-res treble and the Audioquest Diamond does the opposite: to compensate for the PWD's weakness in the treble while taking away a little of the PWD's character in the nether regions. Which is the better performer? I can't say, but boy is there ever a lot of audible difference between USB cables.