Review sample supplied by CuriousCables.com
Retail price: $550 (0.8m/80 cm)
A little over a year ago I reviewed the original Curious USB cable following the suggestion of a reader and was pleasantly surprised by the cable’s performance. Very recently, I was made me aware of the new Curious Evolved USB cable and I decided to review it, and since I also have the original, I can make a direct comparison. Conveniently, this coincided with a request from Mike Lenehan (who builds the Curious Cables for Rob Woodland) to review his new FoilFlex cables and so these were sent along with the Curious Evolved USB cable. For this review, I will focus solely on the USB cables using reference components that I know well: the CH Precision C1 DAC, Aqua Formula xHD DAC, CH Precision L1 preamp and CH Precision A1.5 power amp. The speakers for this review are the Magico S1 MkII and Martin Logan ESL15A.
According to the manufacturer, the Curious USB cable has been designed with one thing in mind – to improve the sound quality of your computer audio system. But that was already the case with the original cable. What differentiates the Evolved?
That is a great question but, alas, one that will not be answered. All that I can see is that the same construction seems to be used with the same braiding and sleeving. Now, the shrinkwrap is blue instead of yellow and the connector’s conductive materials have more of a red/copper-like color instead of the original’s more regular gold-plating. In terms of stiffness, there’s not much between the cables and they seem to be braided in a similar manner.
Here’s what the Curious website mentions on the subject.
As the name suggests, the Evolved is an evolution of the Curious principles, with increased resolution providing more space, separation and three dimensional sound staging. Inner detail is improved, so you’ll hear more of the recording than ever before. According to the designer Rob Woodland, “The Curious Evolved is the best we can do, and will benefit audiophiles who want the maximum performance from their computer-based Audio system”.
So, it will come down to just listening to the cables. Now, I know that there is much debate about the audibility of differences among USB cables. I’m fine with that and you’ll find no attempts here at explaining the technical grounds for these differences. Instead, I will simply relay what I hear. A discussion on a different level is that of burning in or running in with respect to digital cables.
While some cables are more susceptible to this than others, this is a real phenomenon in the analog realm even if the differences can sometimes also be very small in this field. But is it also a thing in the digital world? You’d think not, and indeed, I don’t usually pay much attention to this myself. For example, I find that the Belden RG59 coaxial cables that I use a lot sound the same as they did when they were new and the same goes for most other digital cables.
However, there was one instance in which I was told by a manufacturer (See Antipodes review part 3) that I should pay special attention to the running in of a supplied cable. To put this to the test, I asked for two of said cables of which I laid one aside while I put the other to use. Then, after a period of time, I compared the used cable to the virgin cable and was stunned that there were indeed differences to be heard. It was not earth-shattering but the used cable sounded smoother and more relaxed. And here comes the rub: this concerned an RJ45-terminated network cable between a server and a renderer. Yes, I know. But trust me: I have no interest in hearing these things one way or another, I just do. And I know I’m objective because I test this regularly with friends and the differences heard can often be counter-intuitive or going against what I expect.
With the matter of burn-in in mind and following up on specific reader comments regarding the required burn-in for the Curious Evolved USB cable, I decided to also pay special attention to this aspect.
Although it is claimed that the Curious USB cable changes significantly with burn-in, I have only observed mild effects. After running in for 24 hours I did not find the balance to have changed at all or not enough to really notice. Then, I left it connected permanently between the Antipodes CX and Aqua Formula xHD while continuously playing music while the other cables were laid away and were not used. After more than a week (168 hours) the Curious Evolved had indeed become slightly richer and smoother but otherwise behaved consistently against the other cables. After running in another 100 hours (268 in total) I felt that the cable had not changed anymore and thus, the actual listening could commence.
Because I just finished a review that included the Aqua Formula xHD I am starting with this DAC connected to the CH Precision L1 preamp. The analog cables are two CH Precision Balanced Links and the source is the Antipodes CX Music Server outputting to USB via Core Direct and I’m starting with the Magico S1 MkII’s. To get started, I listened to my most-used USB cables one by one using the same playlist.
My favorite cable prior to the arrival of the CH Precision RoonReady Ethernet_IN HD board was the 747-euro Final Touch Audio Callisto and because I’ve been listening via an ethernet cable since October last year, I’ll start with this cable. The Callisto sounds familiar, not super-tight or ultra-dynamic but nevertheless well-paced and articulate while also fluid and ethereal. It’s a very nice balance between technical perfection and emotional involvement.
The 600-euro CAD USB 1 sounds considerably more robust and sonorous with classic-Wadia-like bass heft, a very convincing acoustical timbre and a darker treble. Teena Marie’s “The perfect feeling” on her album “Beautiful” that contains more acoustical sounds than the rest of the mostly electronic tracks sounded especially more convincing. The more electronic-drum-driven tracks, however, were delivered with less spaciousness and less of the dreamy quality that the Callisto has. But is this “dreamy” aspect supposed to be there? Is this on the album? That’s what I will try and figure out later using the Aqua La Diva CD transport.
The original Curious USB cable has a uniquely “fresh” sound, by which I mean it is fast and lively with an open treble and a communicative midrange. It’s less solid than the CAD and comparatively a little cool and clean. While very exciting, harmonic richness and texture are not the cable’s strongest points. This aspect is revealed now by the Magicos but was not obvious when I first reviewed this cable using the Wilson Watt/Puppy 8 speakers. The Curious is not as dreamy and free-flowingly spacious as the Callisto but it does have wider imaging than the CAD.
Of these cables, I tend to gravitate toward the original Curious and the Callisto. The latter has the most refined delivery and airiest sound and it deviates from the other cables in terms of spaciousness and, in this case by extension, imaging. The cable’s large soundstage leads to the impression that the vocals are more free and better focused than they are with the other cables. This is not actually the case but that’s stuff for psycho-acoustic experts. The Curious is not quite as refined but its focus is just as good and its PRaT and more upbeat and solid delivery make up for this.
Curious Evolved USB
Now it was time to start on the Curious Evolved USB cable. I plugged it in after having listened to the original Curious cable last. Oh, yes, this is something else! Smoother and richer, the bass is fuller and while it is not as solid as the CAD’s it has more body than the other cables in this test. Apart from the bass and the richer tonality, the treble behavior is quite different, too, cleaner and considerably more refined but also darker. Gone is the dryness and lack of tonal saturation. Teena Marie’s “The Perfect Feeling” has the same convincing “real-life” character as with the CAD while electronic tracks have more shimmer and subtle sounds float more freely in a wider soundstage.
Its smoothness does make the Evolved come across as less lively than the original Curious cable. Whereas the latter encourages the inner party-animal, the new cable encourages more introspective listening. More up-tempo songs with tight rhythms sound less impactful as if the transients are slightly rounded. I’m not really sure if this really is the case because the cable’s low-level resolution is actually very good. But to really get all the energy across from hard-hitting R&B, the Evolved is just a little too sweet.
Compared to CD transport
With the USB cables all sounding so differently, how does one know which cable’s delivery is closest to the source? In an absolute sense, this is pretty much impossible to determine but I’ll have a stab nevertheless. Since the Jay’s Audio CDT-2 MkII CD revived my interest in CD transports I have heard a not-inconsiderate number of CD transports and compared them all to the Antipodes music server. The most lively and engaging CD transport that I have heard so far is the Aqua La Diva. Fortunately, the unit that Marco Oudheusden of Hexagon Audio loaned to me is still here. For this part, I used the Martin Logans ESL15A’s.
I should note up front that the Aqua La Diva has a particular sound just like other transports do. And the Antipodes also has a certain character. That’s just the reality of the matter, in spite of what digital theoretics might want to believe. With that in mind, the following is not meant to draw hard conclusions from but more to put things in context.
Comparing the music server to the CD transport using the same album, the Original Curious cable is, in some respects, surprisingly closer than the other cables. Its bass performance is closer to the nimbleness of how the CD transport delivers the bass: fast and agile. The CAD is fuller and more sonorous but that’s deviating from the Aqua’s delivery. The server’s midrange with the CAD is a little static when compared to the more immediate and “springy” CD delivery and in this respect, as well as in terms of airiness and fluidity, the Callisto shows more resemblance to the CD transport. The Curious Evolved, finally, is indeed a little sweet and a little dark, as already noted earlier, but otherwise close to the CD transport in terms of overall balance. While not as lively and immediate as the other cables, it has a super-refined and highly nuanced sound that will never cause listening fatigue.
All of the cables had certain aspects that made the server approach the CD transport in certain areas but none of them made the music server sound exactly the same and I doubt that there are cables that do. CD will always sound different from a file on a music server which will always differ from analog LP playback. So, while these are interesting results, one should keep in mind that all that we are establishing here is how close the Antipodes CX comes to the Aqua La Diva CD transport by using a range of USB cables. There are no absolutes here. That’s why I always keep repeating that the audio hobby is all about finding the right balance for a given system.
But let’s zoom in some more on the music server part and now also involve a local ethernet connection using the CH Precision C1 DAC.
After the L1 preamp had gone back to the manufacturer I changed the testing setup from the Aqua Formula xHD DAC to the CH Precision C1 DAC which has integral hybrid analog/digital volume control and is connected to the A1.5 amplifier directly. The speakers for the remainder of this review are still the Martin Logan ESL15A’s.
The default listening method in this combination is via a direct ethernet cable using the C1’s Roon streaming board. Although all the aforementioned USB cables have their unique traits, the network connection gives me the best combination of speed and articulation on the one hand and natural flow on the other hand. However, this is not to say that network connections are always better. This depends entirely on the implementation and CH Precision has done this masterfully.
When switching from the network connection to the Curious Evolved USB cable, the initial feel is that the USB cable sounds a little bit more relaxed but not slow or undynamic. Listening closer I hear that the overall smoother feel has its origin in a slightly more velvety midrange and slightly darker, more rounded treble. But the real surprise is in how the Evolved USB cable approaches the natural flow of the ethernet connection while giving in only slightly in terms of directness.
Swapping to the original Curious USB cable the sound is more upbeat with sharper transients but it is considerably drier and has less of that alluring organic smoothness and, importantly, less of the natural flow. A cross-comparison with the Final Touch Audio Callisto confirms that this cable still has the most free-flowing delivery but the Curious Evolved USB counters with better bass, more realistic attack and more momentum.
It’s worth mentioning that the CH Precision C1 DAC turned out to be less sensitive to USB cables than the Aqua Formula xHD DAC. With the latter, I found the differences between these cables very easy to hear while with the C1 they are smaller and require more concentrated listening.
Ultimately, with USB cables we are talking nuances even in the case of the Aqua DAC but at this level, nuances do really matter. And as a perfectionist, I totally understand the importance of selecting the best-matching cable for a given system. With this review, I hope to have not only illustrated how the Curious Evolved USB cable sounds but also the importance of understanding how relative of a matter this is.
With the Evolved USB cable Curious has issued a very interesting alternative to the original USB cable. Whereas the original Curious cable is master of transient sharpness and dynamic slam, the new Curious Evolved cable has a sweeter and richer delivery with a more organic and free-flowing perspective while retaining a very large portion of the original’s drive and dynamics.