The debate around the value / importance of USB cables is a tense one in the audiophile world with some people swearing that the cable makes no difference and others believing it does. I personally sit in the second camp. I believe, based on listening to many different USB cables, that the cables do actually make a difference. I have also found that the cost of the cable has no bearing on whether or not it sounds better and personal preferences will also play a part in this question.

This review is a bit different to some others I’ve done. This time around, the wonderful crew over at AudioQuest have loaned me one of each of their USB cables from the entry-level Pearl all the way to the top of the line Diamond that costs more than most headphones, amps or DACs. I have also thrown into the mix some cables I already own just to make sure there is some multi-brand, market context to this test.

You’ll find links to the various cables after each write-up. If you enjoy what you’ve read and are looking into buying one of these cables (or some other alternative), please click through my links to help support this blog. Many thanks and happy reading and listening!

Preamble

Before I get into any details about the cables, let’s cover off on how this review was done. I don’t believe in A/B/X testing for this type of test. For one, it is very difficult to quickly switch between USB cables without having two identical setups and I don’t have those kinds of resources. Secondly, I find that ear fatigue kicks in way too quickly on those types of tests leading to good results early in the test and rapid declines later in the test. This adds an additional variable to the test and negates the value of the A/B/X testing.

Instead of A/B/X testing, I have approached this subjectively. Each cable received a solid 10-15 minutes of listening time with me taking notes and making observations about the qualities of the sound that I noticed for each cable. At each changeover, I repeated the same song in order to hear similarities and differences from one cable to the next before allowing a range of tracks to play so as to reveal wide-ranging characteristics in the sound of each cable.

When it comes to testing cables, I always look at it in terms of which cable(s) I want to go back to after extended listening. It’s easy to get caught up in what one does better or differently to the others, but what really matters is which one is the most enjoyable (and by what margin) so that’s my ultimate test – which cables are the most enjoyable additions to my already immensely enjoyable setup.

One final point: if you are a dis-believer that USB cables could make a difference because USB audio is digital, please check out the video I posted on that topic before continuing as it will help to clarify why some of the cable technologies used by various manufacturers should actually make a difference.

Test Gear

The following setup was used for this test:

• Acer Aspire V Nitro laptop
• AudioQuest JitterBugs on each USB socket (one for my USB dock and one for the USB audio cable)
• Matrix X-Sabre DAC
• Tara Labs Prism RCA cables
• Bottlehead Mainline amplifier
• AudioQuest NightHawk headphones

For all cables, I will list their price (as new from Amazon) for a 1.5m cable.

On with the test…

Generic Cable #1 (black)

• Cost:  free with every USB device ever purchased
• Connectors:  standard metal (I’m not actually sure what they use for generic cables – nickel?)
• Technologies:  none

It’s important to start off by saying that the sound from this cable is completely fine. If this were the only cable I had, I would still be happy, but I know from past experience that there are benefits to be found with upgraded cables so I’m using this as a baseline for what follows.

Generic Cable #2 (clear)

• Cost:  free with every USB device ever purchased
• Connectors:  standard metal (I’m not actually sure what they use for generic cables – nickel?)
• Technologies:  none

This cable is another generic cable that came with a printer or similar device, but this time it has a clear insulation that shows the silver-coloured shielding underneath. I definitely didn’t expect any difference between two generic cables with no special technologies to speak of, but I was shocked to find that the sound from the clear cable was actually more enjoyable than the black generic cable. Instantly, the clear cable had a sense of clarity and definition to it that was more appealing than the black cable. The black cable sounded a bit flat and blunt in comparison.

I didn’t really trust myself on this one so I switched back and forth on the same track and each time I found myself enjoying the sound from the clear cable more than the black cable. The guitars sounded a bit crisper and more tactile, the vocals sounded a bit smoother and there was a slightly greater sense of space between me and the music which made the music overall more enjoyable.

Lesson: if you have multiple generic cables, try a few difference ones – you might find one that sounds better than the others!

AudioQuest Pearl

• Approx. Cost:  $30 (USD)
• Connectors:  gold-plated
• Aesthetics:  black with white pinstripe, fairly stiff

Technologies

• Solid, long grain copper conductors: designed to reduce interference created within multi-strand conductors
• Directional conductors: designed to optimise the flow of noise away from the DAC towards earth
• Solid, foamed polyethylene insulation: designed to hold the conductors firmly in place within the outer insulation. This is important to create an optimal magnetic field between the signal leads and therefore prevent interference between the conductors. Foamed polyethylene is a very efficient and cost-effective insulation because it creates very little interaction with the conductors

At this price, the Pearl might as well be free – it’s very cheap for an aftermarket audio USB cable, but I have to say that the difference is striking when compared to the generic cables. First and foremost, the Pearl recreates the sense of space that I enjoyed on the clear generic cable. It still has a sense of clarity, but it’s not quite as sharp as the clear generic cable. At first take this could seem like a negative, but the clear cable’s sound actually became a bit fatiguing after a while whereas the Pearl was consistently enjoyable even after long periods of listening.

To summarise the sound from the Pearl, it is smooth and clean with a good sense of space. It instantly proves itself to be a better option than the generic cables and is a no-brainer if you’re looking for a budget upgrade to your USB audio system.

AudioQuest Forest

• Approx. Cost: $40 (USD)
• Connectors:  gold-plated
• Aesthetics:  black with green pinstripe and plug accents, fairly stiff

Technologies (over and above the Pearl)

• Solid, 0.5% silver plated conductors: designed to reduce interference created within multi-strand conductors and improve conductivity at the conductor surface (where most of the signal travels) through the use of silver plating
• Hard-cell foam insulation: further improves the stability of the audio signal conductors. This appears to refer to the internal conductors as the website refers to foamed polyethylene on the cable overall.

The jump from the Pearl to the Forest is a little less significant than the jump from the generic cable to the Pearl. That said, there is an improvement in the sound. What I heard was a slight increase in clarity, particularly around the treble, but it doesn’t get edgy like the clear generic cable. In fact, the Forest presents a sound that is at once crisper and smoother than the Pearl. It’s a subtle improvement, but it’s there and for only $10 more, the Forest seems a better option.

AudioQuest Cinnamon

• Approx. Cost: $80 (USD)
• Connectors:  gold-plated
• Aesthetics:  black weave with dark red accents, fairly stiff

Technologies (over and above the Forest)

• Solid, 1.25% silver plated conductors: designed to reduce interference created within multi-strand conductors and improve conductivity at the conductor surface (where most of the signal travels) through the use of silver plating – the higher quantity of silver means that even more of the signal travels via the higher quality conductor

So jumping from the Forest to the Cinnamon brings an increase in silver-plating thickness, but is otherwise only cosmetic. I was curious to see if that increased amount of silver would actually make any difference… and it did.

I don’t fully understand the physics behind it, but there is no doubt that the increased silver content in the Cinnamon created a more open sound with greater clarity, but not any additional treble / harshness to the sound – it just all got better – noticeably. There’s no significant shift in the sound signature of these cables, each one just builds directly on the sound of the lower model, improving it incrementally, but noticeably. It’s nice to see that, so far, every extra dollar you spend does bring noticeable benefits.

The Chord Co. SilverPlus

• Cost: $109 (AUD) – not available on Amazon
• Connectors:  gold-plated
• Aesthetics:  white with light blue accents on plugs, more supple than the AudioQuest cables

Technologies

• 26AWG twisted pair, silver-plated conductors: it’s hard to say if this is a pair of solid core conductors or a pair of stranded, silver-plated conductors in a twisted configuration. The twist would help to prevent noise, but if it’s stranded that can actually add noise internally
• High speed low-loss gas-foamed polyethylene insulation: high quality insulation for cables that has less impact on the signal and insulates the conductors well
• Dual layer high frequency effective shielding: not really described in depth anywhere, but ideally this will prevent external noise from getting to the signal conductors

The SilverPlus sits fairly close to the AudioQuest Cinnamon in both price and features. The features are different, but at a similar overall level as far as I can tell from the somewhat lacklustre descriptions available for the SilverPlus. On that note, kudos to AudioQuest for being so transparent with their designs – they tell you exactly what is going on inside each cable and what features each cable has over the next – you know what you’re paying for (regardless of whether you believe it makes a difference).

The SilverPlus has been my permanent audio USB cable for a couple of years now and I’ve not heard a USB cable better enough to compel me to invest in anything more expensive (or cheaper). I completed a full review of the SilverPlus ages ago so you’re welcome to go read it if you’d like a stronger baseline for this comparison.

Switching from the Cinnamon to the SilverPlus was eye-opening. My beloved champion was instantly trounced! The sound from the SilverPlus suddenly sounded a little soft around the edges. There was a slightly better sense of space in the soundstage, but it came at the cost of a noticeable loss of clarity and resolution. I was heart-broken and my wallet was instantly terrified. The SilverPlus is still a great cable – don’t get me wrong – and I would choose it over many more expensive competitors on the market, but not the AudioQuest offerings. In fact, I would choose the ‘cheaper’ Cinnamon over the SilverPlus at this point.

AudioQuest Carbon

• Approx. Cost: $170 (USD)
• Connectors:  silver plated
• Aesthetics:  black weave with charcoal accents – very stealth, fairly stiff

Technologies (over and above the Cinnamon)

• Solid, 5% silver plated conductors: even more silver means that more of the signal travels via the higher quality conductor
• Carbon-based, 3-layer noise dissipation system: shields the shield of the cable to further prevent the ingress of noise (RFI, etc.) into the ground plane

The research I’ve done on DACs and digital audio has made me very aware of how important a clean ground plane is in digital audio. Because it acts as the reference for every calculation of voltage in the digital audio system, the cleaner you can keep your ground plane, the cleaner your audio will sound thanks to the prevention of significant amounts of jitter and noise. The Carbon USB is a big step in theory because it not only ups the ante on the AudioQuest technologies so far, but it introduces a whole new technology. So, does the doubled price tag bring a double increase in sound quality?

Now, it’s impossible to measure quantities in sound so that was a poor choice of words, but I’m not going to edit it. Instead I’m going to answer it by saying that I can’t measure the sound, but I would absolutely buy the Carbon over the Cinnamon if I had the cash. There is no doubt at all in my mind that the Carbon is a noticeably superior cable. In fact, the jump from the Cinnamon to the Carbon is easily the biggest increase I’ve heard so far, including the jump from generic USB cables to the Pearl / Forest cables.

Connecting the Carbon USB to my system brought a depth and timbre to my music that I haven’t heard before from my system. It was like going from an average MP3 rip to a beautifully mastered, lossless high-res file – I was instantly addicted. There was more space in the sound, both in the overall size of the soundstage, but also in terms of the space around each instrument / sound. I can only assume that this is a result of the better isolated ground plane allowing every sound to be more accurately rendered by the DAC with no hash / background noise to muddy the end signal.

Once again, the signal is unchanged in its overall character / signature, but everything just got clearer and more open.

iFi Mercury

• Approx. Cost: $250 (USD)
• Connectors:  gold plated
• Aesthetics:  black weave with silver plugs and black silencers, supple like the SilverPlus

Technologies

• Heavy OHFC continuous cast copper: the many terms for various types of copper become confusing and interchangeable after a while to the lay-person (like me) and unfortunately, this description doesn’t clarify if the Mercury uses a stranded or solid core for each conductor. Continuous casting is good because it means there are no “boundaries” where one copper crystal ends and the next one begins, but it doesn’t stand out as better in any way than the cables we’ve looked at so far
• Dual copper and aluminium shielding: designed to maximise the range of frequencies shielded to prevent as much noise as possible
• Metal oxide ceramic RF noise silencers: adjustable silencers designed to maximise cable noise resistance
• Foamed polyethylene insulation: as per the other cables in this comparison

The Mercury is another USB cable that I personally own and it comes at a higher price tag than the incredibly impressive Carbon, but it does offer some interesting features that are unique in this comparison. The adjustable silencers are an interesting feature. In my experience, the silencers always end up in the exact same positions – one at each plug (as recommended) and the middle one dangling pretty much in the middle of the cable where the weight of the cable hangs. Moving the silencers has no noticeable impact on the sound. Given that there are very definite differences caused by some of the features already discussed, I would expect to hear at least some subtle changes as I move the silencers along the Mercury, but the reality is that nothing noticeable happens.

Other than the apparently redundant silencers, the sound from the Mercury is quite nice, but very flat. As soon as I switched from the Carbon to the Mercury, I felt like I’d lost the realism of the sound – everything became 2-dimensional and lost the “soul” that was so exciting to hear through the Carbon. In fact, I have for some time now preferred the much cheaper SilverPlus over the Mercury for this very reason. There’s no doubt that the Mercury is a good upgrade on generic USB cables, but I believe it’s outclassed in this particular comparison. Some people will really like the slightly brighter sound of the Mercury and it’s emphasis on width over space, but I would personally stick to the SilverPlus, Cinnamon or Carbon before the Mercury.

AudioQuest Coffee

• Cost: $350 (USD)
• Connectors:  silver plated
• Aesthetics:  black weave with dark brown (coffee) accents, fairly stiff and with a fairly bulky DBS unit hanging from the type-B (DAC) end

Technologies (over and above the Carbon)

• Solid, 10% silver plated conductors: even more silver means that more of the signal travels via the higher quality conductor
• 72V Dielectric-Bias System (DBS): creates an electrostatic field to stabilise the insulation for uniform impact on the signal. All insulation has some effect on the signal, but a non-stabilised insulation can effect different frequencies differently and can ‘smear’ the sound. The DBS aims to prevent this.

So, another doubling in price and another entirely new technology (in addition to higher silver content). Will the results be equally as impressive?

Before I answer that question, I want to state that I am going in sceptical. The DBS seems a little gimmicky to someone like me without the physics expertise to fully appreciate how significant the interaction between insulation, conductor and electrons may actually be. I guess what I’m saying is that I was expecting a subtle difference or no difference as I swapped from the sublime Carbon USB to the Coffee.

So, the answer to the question is a very unsatisfactory “maybe” when it comes to whether or not the improvement from the Carbon to the Coffee is as impressive as from the Cinnamon to the Carbon. This is a much harder one to pick which, in itself, suggests that the improvement isn’t as dramatic. But… as I flicked back and forth (as quickly as is possible) between the Carbon and the Coffee, I couldn’t help but feel like the Coffee brought with it a slight increase in resolution thanks to a smoother overall sound. Signature-wise, the cables continue to be identical, but the Coffee seems to sound just a little more effortless and a little more lifelike than the Carbon.

At this point, the extra money starts to become harder to justify I think. If you have the budget I would probably recommend the Coffee, but if you needed to save your clams for other purchases, I believe most people would be completely happy with the Carbon and an extra $160. In fact, that got me thinking… is it better to buy a Coffee USB or a Carbon USB with a couple of JitterBugs?

AudioQuest Carbon + JitterBug vs AudioQuest Coffee (only)

• Approx. Cost of Carbon USB + 2 x JitterBug: $270
• Approx. Cost of Coffee USB:  $350

I reviewed the brilliant little JitterBug separate from this review and while I have used the JitterBugs for this whole review so far (to test the cables with minimal interference from the noise from my computer), but now it’s time to see if a step up in cables or a couple of JitterBugs make a better investment.

Moving from a JitterBug-free setup with the Coffee USB, I then swapped to the Carbon USB, but added a single JitterBug (with the Carbon connected to it). There’s no doubt that the addition of the JitterBug significantly reduced the gap between the two cables, but there is still a smoothness to the Coffee that the Carbon/JitterBug combo can’t quite match. The Carbon/JitterBug sound still has just a slight edge to it in comparison that makes the cymbals sound less realistic and masks some of the mid-range timbre you can hear when using the Coffee. Time to add a second JitterBug to the Carbon setup…

So now, with two JitterBugs plus the Carbon USB, things are sounding pretty great, but it still doesn’t quite catch up to the Coffee. When I switch from the Carbon/Twin-JB combo to the Coffee there is no doubt which sounds better, even with the extended delay of switching off the DAC, disconnecting, reconnecting and powering up again. The Coffee has a mid-range quality that the Carbon just can’t match, even with a couple of JitterBugs in support. The JitterBugs definitely help, they just can’t close that gap completely so the verdict here is simple. If your budget is sub $300, stick with the Carbon, but throw a Bug or two into the mix. If you can stretch to $350, don’t even hesitate – go for the Coffee and if you can add a JitterBug or two then all the better.

AudioQuest Diamond

• Approx. Cost: $700 (USD)
• Connectors:  silver plated
• Aesthetics:  black weave with white / silver accents, fairly stiff and with a fairly bulky DBS unit hanging from the type-B (DAC) end

Technologies (over and above the Coffee)

• Solid, 100% silver conductors: a pure silver conductor is about as good as it gets and this is a huge jump from 10% silver plating in the Coffee to 100% silver content in the Diamond

We’ve doubled the price again, but this time the added technology list is much shorter. That’s not a criticism of the pricing though because the increased cost of pure silver conductors compared to 90% copper conductors makes sense. The question though for me is whether or not the increased cost of the materials results in an equally improved auditory experience.

This is the most interesting comparison of all the cables I’ve tested I think because there is once again a significant change in the sound between the Coffee and the Diamond cables, but at first I found myself preferring the sound of the Coffee because it has a slightly greater sense of warmth and a beautifully focussed mid-range. Switching back to the Coffee though left me longing for the space I heard with the Diamond. With the Diamond USB cable, the soundstage stretches right out to each side whereas the Coffee brings it all in a bit tighter resulting in greater focus on the mid-range and the centre of the soundstage.

In a way I prefer the slight warmth of the Coffee, but then I wish for the same sense of openness and full-range clarity that the Diamond presents so it’s a really hard one to split here. I think the conclusion for me is that the Diamond is probably the cable I’d choose in an unlimited budget situation, but I could be equally satisfied with the benefits brought by the still-outstanding Coffee USB in the event that $700 seemed like too much for a cable. There’s no doubt in my mind after this comparison that the Diamond is the best cable of the bunch and is a worthy upgrade from the Coffee. The only question remaining will be budget and that’s a very personal thing.

Conclusion & Final Thoughts

This has been one of the longest reviews I’ve ever written (in terms of the time it took to write). It’s taught me a couple of interesting things that I thought were worth sharing:

1. Even a “cheap” cable from a reputable cable company can improve your USB audio. But…
2. Not all USB cables are better than the generic ones or cheaper options from other companies – do your research
3. Some of the technologies that can sound like snake oil and voodoo actually do work (and it’s best to let your ears be the judge even if you think it’s hogwash)

So, with all this said and done, let me wrap up by saying that my conclusions from this review are quite simple. Buy the best USB cable you can afford and justify because it will improve your system. I wouldn’t recommend spending more on the cable than the DAC / amp / headphones, but the cable can help to prevent noise from reaching your DAC so even a cheap DAC will benefit from a USB cable upgrade. In fact, a cheap DAC will generally handle noise worse than a better DAC so the cable may be even more important.

To my mind, a proportional spend on the cable compared to the DAC makes some sense from a purely financial perspective. For example, I don’t think I could justify the cost of the Diamond USB for my DAC which costs roughly the same, but I am quite happy with the idea of the Coffee at roughly 30-50% the price (depending on exchange rates, etc.) That’s a very personal equation so don’t take it as a rule so much as an idea. Having now had the chance to compare every option in the AudioQuest range I also have no problems fully recommending their USB cables. I started this test expecting to see a dramatic display of the law of diminishing returns, but I can honestly say that every cable in their range demonstrated a significant improvement over the lower model so you can safely spend whatever you’re comfortable with and know that you are really getting the best value for money with the AudioQuest range. I can’t necessarily say the same for some of the other USB brands I’ve tried over the years.

I hope this review has helped clarify the somewhat murky waters of USB audio and USB cables specifically. Please feel free to comment below if you have any questions I can help with.