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First Listen: AudioQuest Diamond USB cable

First Listen: AudioQuest Diamond USB cable

Once Hi-Fi+ Issue 123 hits newsstands in June, readers will discover that Nicholas Ripley has done a fascinating survey in which he compares three mid-priced USB cables—from AudioQuest, Gutwire, and Nordost—versus a standard, non-descript, freebie USB cable. I won’t spoil the fun I’m sure you’ll have when issue 123 arrives, but suffice it say that our Mr Ripley did hear consistent differences between each of the mid-priced cables, both in comparison to each other and to the freebie. So much for the ‘bits is bits’ theory, at least for high-performance audio purposes.

If we turn back the clock a number of years, I would have to confess that I was at one point a confirmed USB cable sceptic. My reasoning was that, since cheapo USB cables almost invariably manage to transfer data successfully from PCs to outboard USB hard drives or printers and the like, why would there even be a need for upscale ‘audio-grade’ USB cables?

I maintained that stance right up until, some years ago now, I was loaned a couple of specialty-grade USB cables, only to discover that, lo, higher-quality USB cables really did offer readily discernible sonic benefits (and not the kind you have to work to hear, but rather the kind where you wind up thinking, “Oh man, the sonic benefits of those USB cables seem pretty darned obvious…”).

, First Listen: AudioQuest Diamond USB cable

While the exact data transfer mechanisms at work might be subtle and difficult for those of us who are not engineers, physicists, and/or data transfer theoreticians to understand, the fact that good USB cables can and do improve sound quality is easy to observe and dirt-simple to grasp. You listen to your digital audio system with and without good USB cables in play, and note your own reactions to the music. If you’re at all like me, you may find you have a clear-cut, unequivocal preference for the sound with higher-performance USB cables in play. Case closed, end of story.


But, being audiophiles and therefore by definition being limit-pushers, who among us would not—sooner or later—think to ask, “If good USB cables make digital audio sound better, what would happen if I used truly great USB cables in my system?”  With that thought in mind I recently met up with AudioQuest’s Joe Harley, Senior VP of Marketing and Product Development, and—after explaining that my once highly advanced USB cables had at this point grown somewhat long of tooth—I asked if he might loan me a set of AudioQuest’s top-shelf Diamond-series USB cables so that I could assess for myself how much sonic progress had been made in recent years.

Mr. Harley obliged, and sent me not only two sets of top-of-the range AQ Diamond USB cables (1.5M, $698.75; and 3M, $998.75), but also two sets of third-from-the-top AQ Carbon USB cables for comparison (1.5M, $168.75; and 3M, $248.75).  

Why two sets each of the AudioQuest USB cables? The answer is that sometimes I run my system DACs from an AURALiC ARIES that resides in one of my equipment racks so that it needs only a fairly short USB cable, and at other times I run my DACs from a Lenovo-based music server, which is positioned across the room from my audio racks and thus requires a longer cable. (At Joe Harley’s recommendation, we avoided using 5M USB cables, even though AudioQuest offers them, as Harley felt sound quality might be better with the shorter cable runs.).

, First Listen: AudioQuest Diamond USB cable

Since AQ’s Carbon USB cables are among the models covered in depth in Nicholas Ripley’s soon-to-be-published survey article, I’ll set them aside for purposes of this blog. But, I have been very excited by my findings on the top-tier Diamond models and felt compelled to share them with you.


AQ’s Diamond USB cables pull out all the stops and therefore feature 100% perfect-surface silver conductors (that is, solid silver—not just silver-plated—conductors), which AQ suggests minimise “distortion caused by the grain boundaries that exist within any metal conductor, nearly eliminating harshness and greatly increasing clarity compared to OFHC, OCC, 8N, and other coppers.” Then, AQ gave its Diamond-series USB cables sophisticated foamed-polyethylene insulators chosen “because air absorbs next to no energy and Polyethylene is low-loss and has a benign distortion profile.”

, First Listen: AudioQuest Diamond USB cable

To further minimise the potential sonic effects of the cable dielectrics, AudioQuest fitted the Diamond USB cables with the same, patented 72V dielectric-bias system that is found on the firm’s upper tier analogue cables. The DBS system applies a bias voltage across the cable’s insulators with an eye toward minimising “both energy storage in the insulation and the multiple non-linear time delays that (can) occur.” The result, says AQ, is that “sound appears from a surprisingly black background with unexpected detail and dynamic contrast.”

Next, in the interest of “preventing captured RF interference from modulating the equipment’s ground reference” the Diamond USB cables use a carbon-based 3-layer noise-dissipation system. Finally, cable terminations feature ‘direct-silver’ plated pins and are attached using AQ’s proprietary solder (a type of solder said, oddly enough, to sound better and to provide more durable and reliable connections than conventional ‘silver solder’).

, First Listen: AudioQuest Diamond USB cable

As you can tell from some of the passages I’ve quoted above, AQ’s product messaging is some of the best going, but do the Diamond-series USB cables, which are obviously chock-full of technical features, actually sound as good in reality as they do on paper? In a word, yes!


I have been logging a great deal of time with the iFi Audio Retro music system that I blogged about last week in order to give the system some extra run-in time. This was in the hope that the system’s LS3.5 mini-monitor speakers would have a chance to loosen up so as to deliver a more full-bodied sound, and I’m pleased to say they’re coming along nicely. Throughout this process I had been feeding the Retro system’s USB DAC section from my Windows-based music server, using the USB accessory cable that iFi thoughtfully included with the system. I felt the system sounded good with the stock iFi-supplied USB cable, but when the AQ Diamond-series cables showed up on my doorstep, I just couldn’t resist doing a USB cable swap and the results were impressive indeed. Here’s what I observed.

, First Listen: AudioQuest Diamond USB cable

First, low-level details—and especially high-frequency harmonics, reverberant cues in the music, and other small textural and transient details—became much more audible, intelligible, and coherent with the Diamond USB cable in play. This wasn’t a small difference. But then, perhaps as a result of that first set of sonic improvements, another wonderful thing happened, which is that the system fairly exploded into a whole new realm of intensely holographic, three-dimensional sound. This one was one of those changes so dramatic that, figuratively speaking, it grabs the listener by the lapels and says, “Now please stop what you’re doing, sit down, be still, and pay very close attention to the way this piece of music unfolds.” Even from just a few feet away, the little iFi monitors—aided and abetted by AQ’s Diamond USB cable—began throwing beautifully and ridiculously expansive 3D soundstages. It was truly something to behold.

And then, I switched from speakers to headphones, which caused my jaw to drop yet again. The iFi Retro Stereo 50 amp had struck me from the outset as having good performance potential as a headphone-orientated amp/DAC, but the Diamond USB cables dramatically converted that potential into practical reality. Sonic images through my HiFiMAN HE-560 planar magnetic headphones suddenly took on almost sculptural qualities of shape, solidity, and dimension. In fact, in trying to think about the impact the Diamond USB cable was having on the music, the best analogy I could come up with was that regular USB cables give you something akin to a high-quality photograph of a sculptural object, whereas the Diamond USB cable enables you—figuratively speaking—to hold the sculptural object in your hands, to examine its contours, and to explore at length its variegated textures and surfaces. In short, with the Diamond USB cable installed, there is a whole different level of vital connection with the music.

, First Listen: AudioQuest Diamond USB cable

I realise that last paragraph probably sounds like hyperbole gone wild, but the sonic effects of the Diamond USB cable are pretty much as I’ve just described them, so there you have it. Let’s just say the Diamond USB cable either helps place you in the recording space, or else helps to bring a good facsimile of the recording space into your room (or to that oh-so-intimate space between the ear cups of your favourite headphones). Either way, it’s a very desirable sonic outcome, wouldn’t you agree?


Apart from the obvious issue of price, are there any drawbacks to the Diamond USB cable? I can think of only two and neither of them are ‘deal-breakers’. First, the Diamond USB cable is relatively stiff compared to many USB cables I’ve encountered, meaning you may need to take some time to bend it to the desired shape so as to fit with other components in your audio rack. Second, the power pack for the Diamond USB’s DBS system is comparatively bulky and is fitted on the ‘DAC end’ of the cable. AudioQuest deliberately leaves some slack in the cable that connect the DBS module to the main cable, so you can move the DBS module around to a point, but even so you’ll need to make sure the DBS module doesn’t conflict with other cables connected to your system. This is especially relevant in an all AudioQuest system, where the DBS modules of interconnect cables are at the source end: you could, conceivably, have three DBS modules very close together on the rear panel of a comparatively small DAC. But, once you’ve got these minor ergonomic issues handled, everything else about the cable is a pure delight.

Is it crazy talk to consider spending between $700 and $1,000 on a (gulp!) USB cable? Some would say it surely is. However, if you accept the Diamond USB cable at face value, plug one in, and then listen to what it does, you might conclude that you could easily spend an equivalent sum on other component upgrades and actually wind up with much less in the way of discernible sonic benefits. And just that quickly, it dawns on you that perhaps acquiring AQ’s über-expensive Diamond USB cable isn’t such a loony idea after all.

, First Listen: AudioQuest Diamond USB cable

Even if you think you’ll never, ever buy one, I urge you to go hear AQ’s Diamond USB cable in action if you get the chance. If nothing else, it will be an interesting learning experience. At the same time, let me caution you that prolonged listening to digital audio systems through AQ’s Diamond USB cable is potentially habit-forming (or at least that’s been my recent experience). After all, once you’ve experienced digital audio taken to the next level via a super-capable USB cable, its only natural that you might want to make such a cable your own. Hey, don’t say we didn’t warn you…

Happy listening. 


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