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COMPARISON: Clou Red, Stefan AudioArt Equinox, Cardas Prototype

post #1 of 86
Thread Starter 
Clou Red Jaspis, Stefan AudioArt Equinox, Cardas Prototype:
Audiophile-Quality Headphone Cables for the HD-580/600

Well they say that time loves a hero
But only time will tell.…

-- Little Feat in "Time Loves a Hero"

The last time I performed a search of the "headphones" field of the member profiles at Head-Fi, the Sennheiser HD-580 and HD-600 headphones (together) were listed more than any other headphones by a pretty wide margin. These headphones (especially the HD-600) have earned their place as audio legends, not just in the world of headphone hobbyists, but in the hi-fi world in general. A lot of new headphones will be tried, praised, loved and then discarded as trendy models whose times have passed -- few will earn the longstanding stature accorded the HD-580/600's.

< looks around and sees a bunch of people with other headphones on leaving the room with disgusted expressions on their mugs >

Okay, HD-580/600 fans, by now we're the only ones left reading this review, and we're the specific target audience of the products I'm reviewing here: replacement cables for the HD-580/600 headphones. On hand are the Clou Cable Red Jaspis, Stefan AudioArt Equinox, and a prototype cable by Cardas that should be available within a month or two.

When you consider how much research, time and money we put into our audio systems -- source component, interconnects, headphone amp, power conditioning, power cables, tweaks, and, of course, headphones -- it seems sorta silly that headphone enthusiasts are pretty much always stuck with whatever cable the manufacturer decided to include with the headphones. For reasons obvious to audiophile types, many of us refuse to settle for the interconnects that come wrapped with wire ties, and bundled with our components. And, c'mon, how many of us would be thrilled about buying a set of speakers with captured speaker cables? Not me. And my headphones are essentially my primary speakers.

Look & Feel

Clou Red Jaspis. Last year I started my aftermarket Sennheiser HD-600 cable adventure with what was then one of only two choices on the market, the Clou Red Jaspis (the other choice was the Clou Blue Jaspis). Constructed of 99.7% pure copper conductors plated with 99.99% pure silver, and triple-shielded, the Clou Red seems well constructed; but the fit-and-finish, though good, is not up to the standards of the Cardas or Stefan AudioArt cables. Both the Clou and the Equinox use the Sennheiser earpiece plugs from a stock cable, which means there's a splice just aft of each of the two earpiece plugs. On both of these cables the splices are covered up with heatshrink. Whereas the Equinox has a nice, straight flow through the splice, with what feels like a very clean soldering job underneath the heatshrink, the Clou is more bumpy underneath the heatshrinked splices, and the juncture doesn't flow as straight as on the Equinox.

Aesthetically, the Clou Red Jaspis is definitely an attention-getter. The first thing I noticed was the shocking red color of the outside jacketing -- I mean, it's about the reddest looking red I've ever seen. This red jacket is also somewhat grippy, which is far from ideal to me for a headphone cable. This grippiness means the Clou tends to snag on things that a more slippery outer material might mercifully slide out of. But the red color and the grippy outer surface are tolerable. What isn't tolerable to me is the stiffness and weight of the cable. The best analogy I can think of is one that Head-Fi member/moderator Apheared shared with me -- physically, the Clou feels like one of those stiff gag "invisible dog" leashes. This stiffness and weight would be acceptable for an interconnect, but for a headphone cable it's just not practical for this HD-600 owner. At the end of the day, it was the stiffness and weight that had me selling my Clou cable, despite the fact that I preferred it sonically to the stock HD-600 cable. Luckily, Head-Fi member roll-man was kind enough to offer to let me borrow his Clou Red (since I sold mine almost a year ago) to compare to the Equinox and Cardas directly (thanks again, roll-man).

The Clou Red retails for US$119.00.

Stefan AudioArt Equinox. The Equinox is far more flexible than the Clou, not quite as floppy-flexible as the stock cable, and a bit more flexible than the Cardas. In addition to being the most flexible of the three aftermarket cables, the Equinox is clearly the looker of the bunch. Yowza. It is significantly better in terms of fit-and-finish than the Clou Red to my eyes and hands, and at least the equal of the Cardas in this regard, with one exception. As I mentioned earlier, the Equinox, like the Clou, currently uses the earpiece plugs from the stock Sennheiser HD-600 cable. In other words, they have to splice in order to connect their cables to the pig-tailed ends of the stock earpiece plugs. Given that this was likely Stefan AudioArt's only option, they did a good job with the splices. The heat-shrinked connections feel much smoother, and look significantly straighter and neater, than the Clou's.

The Equinox's black woven Techflex outer jacket is downright gorgeous to look at. It's also very slippery, making the Equinox far less likely to snag on objects like drawer pulls, chair arms, etc. The white heatshrink accents and white Teflon insulation on the twisted earpiece cables combine with the black outer Techflex covering to give the Equinox a decidedly classy appearance. I can't imagine anyone objecting to the way this cable looks. Unlike its two competitors, the Equinox is not shielded. It uses a quad-braid design for RFI rejection. The braid feels very tight and uniform underneath the Techflex covering, breaking into a pair of two lightly twisted conductors per side.

The Equinox that Stefan AudioArt sent to me came terminated with a nice mini-plug, with an included ¼” adapter. I would have personally opted for ¼” termination, and may order a custom length Equinox configured just this way.

The Stefan AudioArt Equinox retails for US$ 189.00 in a standard 9-foot length.

Cardas Prototype. The Cardas prototype is very flexible (though a bit less so than the Equinox), and has the smallest overall diameter of the three. It comes covered with a smooth blue outer jacket that is neither slippery nor grippy -- it’s smooth enough that it doesn’t snag easily. This cable is much easier to manage and handle than the Clou. Though not as pretty as the black Techflex-covered Equinox, I find the Cardas cable much more attractive than the obnoxiously red Clou.

The Cardas cable uses Cardas’ famous and patented Constant-Q construction and Golden Ratio conductor configuration in a shielded design. It came terminated with a Switchcraft ¼” plug, but is expected to come to market with a new plug developed by Cardas to specifically help eliminate crosstalk.

Build quality of the Cardas cable is superb. This cable trumps its competitors in at least one very significant build aspect -- Cardas used their resources and know-how to come up with custom earpiece plugs. These custom plugs obviate any need to splice factory connectors from a stock cable onto the conductors. As is the norm with Cardas, the fit-and-finish impresses, despite the fact that the unit I have is just a prototype.

The Cardas cable for the Sennheiser HD-580/600 is expected to be priced around US$ 149.00.

Sonically Speaking

I should first establish a quickie opinion about the stock HD-600 headphones. To me, the stock HD-600s have a superb tonal balance, with deep bass extension not typically associated with headphones of open design. In the rigs I've tried them in, the HD-600s are almost invariably smooth, laid back, and reproduce soundstage in a way only a couple of headphones I've heard can top. In stock mode, plugged into a good rig, the HD-600s are highly resolving to my ears. They give vocalists and instruments alike a concrete sense of physical space if the recording does (and if the equipment earlier in the chain passes it along). In stock mode, microdynamics are an overwhelming strength of the HD-600s. Macrodynamics are better than average with stock Sennheiser HD-600s to my ears, but certainly not the biggest strength of these headphones.

So how is the Clou Red sonically to my ears? Good. Better than the stock Sennheiser cable overall, in my opinion. Bass weight was subjectively improved, though bass control didn't seem to be much improved (if at all) versus the stock cable. I didn't experience much midrange improvement with the Clou Red through my rig, which, given the midrange strength of stock HD-600s, is a tall order anyway. High frequency reproduction is significantly altered, and to me this is where the both-blessing-and-curse syndrome afflicts this cable. Treble extension is subjectively higher with the Clou Red, compared the stock cable. The problem to me is that, at times, treble reproduction with the Clou Red Jaspis can be "splashy" (a word typically reserved for the domain of professional reviewers, but the most appropriate audiophile adjective I could think of to describe it). I made a few comments about the Clou’s sonic characteristics in an earlier preliminary Cardas review, and those comments still stand. The Clou (to my ears) has a slight sense of tonal disjointedness -- as if the highs are takin’ off and leaving everything else slightly behind. Though I prefer the Clou to the stock cable, its performance is clearly not as refined as its newer competitors to my ears.

The Equinox sounds to me like the cable the Clou Red aspired to be. Bass extension seems subjectively better, and so does overall bass control and solidity. Treble extension seemed to improve after a couple of weeks of use, but still not much further to my ears than the stock cable. What has happened to the treble, though, is that it is now significantly more refined than the stock cable, and also much smoother than the Clou -- it never gets splashy. As I stated in my preliminary impressions of the Equinox, triangles ring clearer, cymbals hold on to their shimmer better versus the stock cable and the Clou. I do wish, however, that the Equinox provided more treble extension to go with the increased treble resolution. Unlike the Clou, the Equinox also provided notable midrange improvement. The tonal balance of the Equinox is definitely more “together” than the Clou to my ears. This is a very smooth-sounding cable.

Whereas the Clou neither hurt nor helped the HD-600’s already excellent soundstaging, it is without question an Equinox strength. Stefan AudioArt brags about soundstaging on their web site, and it's not fluff -- it is noticeably better and more room-filling (or should I say "head-filling") than the stock cable. This is something I noted in my preliminary impressions, and thankfully something that has remained consistent since then.

The Cardas is the least like any of the other cables, including the stock one. As I stated in my preliminary review: on a scale with “warm and soothing” on one side and “hyper-revealing/unforgiving on the other”, I’d place this prototype headphone cable squarely between the midpoint and “hyper-revealing”. I think it’s maybe the perfect foil for the HD-600’s laid-back presentation -- perfect in that it opens up the detail across the audible spectrum, but with such even-handedness as to keep the wonderful, very musical HD-600 character intact. To my ears, there is absolutely no sense of tonal disjointedness with the Cardas headphone cable prototype. With it installed, my HD-600’s aren’t overly bright, and not overly warm -- they’re so just right with most of my recordings.

Upon first listen, the first specific sonic thing I noticed about the Cardas cable’s sound was the increased treble extension. While I wasn’t previously of the opinion that the stock HD-600 was in any way treble deficient, I’d have a hard time going back to it now. The Cardas cable really manages to convey greater high frequency extension than any of the other cables, reaching in and scooping out treble information I had no idea my HD-600s were capable of delivering. And it’s good treble -- not hissy or splashy in any way. I will go so far as to say that the Cardas cable coupled with my HD-600s in my rig sound somewhat -- dare I say it? -- electrostatic in their ability to flesh out the most finite details.

For the purpose of this review, I listened to several CD’s with all four cables.

David Gray's White Ladder CD (RCA 07863 69351-2) is one of my favorite recent pop/rock albums, and is a good recording with mild, smooth treble, and an unmistakably chesty sound (a bit too chesty on some tracks). On the slightly mid-bass-thick track (and the album’s biggest hit), “Babylon,” the Clou booms a bit too much (particularly at the beginning of the song), and poor David gets pushed back a little too far as a result. However, the album's already smooth treble (maybe even rolled off at times) actually plays well with the Clou. The Equinox exhibits better bass control with this track, reining in much of the boom the Clou presented. It also projects a much fuller soundstage than the Clou or stock cable, and maybe even a wee bit bigger than the Cardas. The Cardas cable goes even further than the Equinox in terms of keeping this track together. This recording’s overly soft treble is allowed to pass more freely and effortlessly through the Cardas cable. The Cardas cable also did the best job of moving David Gray’s vocals closer to the front on this track. Overall, this track sounded best to me by a significant margin through the Cardas cable.

Maybe my favorite pop/rock album of all time, Radiohead’s OK Computer (Capitol CDP 7243 8 55229 2 5) is, unfortunately, not a reference quality recording. It’s a good recording, but it definitely has an edge that isn’t screaming for cruelly unforgiving playback. Phil Selway’s cymbals in “Subterranean Homesick Alien” and “Let Down” can sound ill defined at times, almost completely smearing on some of the notes. These tracks certainly don’t benefit from the Clou’s concomitantly splashy treble -- I actually preferred the stock cable to the Clou for these tracks. The Cardas cable wasn't particularly friendly to this recording either, opening the door wide open to this recording’s mild (and sometimes more than mild) faults. However, the Cardas never lost its composure like the Clou did. The milder, more forgiving Equinox favors recordings like this, and also recordings that are downright bad (like at least half of the pop/rock CD’s from the 80’s I’ve got).

Miles Davis’ Kind of Blue SACD (Columbia CS 64935) is, in addition to containing great music, a phenomenal album for evaluating audio gear. I’ve heard the version of “So What” on this album countless times, so I know it well -- very well. How beautiful is that opening with Bill Evans’ piano and Paul Chambers’ bass greeting each other politely before they walk lock-step together very briefly afterwards? In that very brief passage at the beginning, after the “greeting”, when the piano and bass are taking the exact same steps, the Clou seems to let loose the bass just a little too much, resulting in a light masking of each instrument’s space, when compared to the Equinox and the Cardas (but still bettering the stock cable). The Equinox does a superb job of keeping them separated. It also adds a bit of sweetness to an already sweet Coltrane sax, and puts an even softer leading edge on Miles’ horn. Whereas this might be good to some, detail freaks might want just a little more reed and spit. If that’s what you want, the Cardas is probably what you’re looking for. In that brief passage, the Cardas makes it easier to mentally pick out and isolate the piano and the bass if you want to, as they’re carved out individually with much precision, but still flow well together when listened to as a whole. The Cardas cable also pays the most respect to the full life cycle of a Jimmy Cobb cymbal touch -- I’ve never heard such lovely decay of that instrument in this recording as I have with the Cardas cable between my Max and HD-600s. As far as conveying the band’s space and soundstage, the Cardas and Equinox seemed about equal, both besting the Clou and stock cable. Overall, this track sounded best to me through the Cardas cable. But there are times I could see myself wanting the softer side of this recording, and I’d favor the Equinox when experiencing one of these moods.


The Clou Red and Blue used to be the only choices in town if you wanted to replace your HD-580/600’s cable. Despite the fact that I found the Clou Red to be a sonic improvement over the stock cable, it wasn’t enough of an improvement to my ears to make dealing with its stiffness, weight, and tacky outer covering worth it. Faced with what I feel are two much more able competitors in the Stefan AudioArt Equinox and the Cardas cables, I can’t recommend the Clou Red Jaspis in its current version.

Based on my preferences and my experience with these cables in my rig, I’d recommend the Equinox for those who listen to a lot of poorly mastered CD’s -- yeah, I’m talking to you, 80’s pop/rock fans. I also recommend the Equinox to those who simply prefer their music with a warmer, more polite presentation. Let’s face it -- some folks just don’t dig the brutal honesty of totally revealing. The Equinox also presents a large, open, airy soundstage if the recording and the rest of the equipment permits. I will likely buy a custom length Equinox for my second set of HD-600s for when I need the soft, forgiving touch of this cable.

Overall, the Cardas cable is my first choice of the three for my main rig. It is very revealing without sacrificing musicality. It also throws a mighty soundstage, if not quite as cavernous as the Equinox. The Cardas' treble extension is truly something to behold -- it really takes the HD-600s to the another level in terms of high frequency extension and timbre. The Cardas would be my first recommendation to those listening mostly to good to reference quality recordings. I also think HD-580/600 owners who listen primarily to classical and jazz should give the Cardas a try first. I've already got my name in the hat to buy a production model the moment it’s available. Keep in mind that the prototype I reviewed did not have the new, fancier crosstalk-fighting plug that Cardas is developing, so Cardas fully expects production models to be even better still -- I'll report on the production version soon after it arrives.

If you’ve read this lengthy review this far, you must be a dedicated HD-580/600 owner. Just remember, friends, that the cable comes off our headphones, and you do have choices.

Associated Equipment
  • Digital Sources: Sony SCD-C333ES SACD/CD player
  • Headphone Amplifier: HeadRoom Max (2001 model
  • Headphones: Sennheiser HD-600
  • Cables: Interconnect: Cardas Neutral Reference, Acoustic Zen Silver Reference. AC: Acoustic Zen Tsunami, BPT C-7, Tara Labs RSC Air
  • Miscellaneous: Price Wheeler Brick Wall PW8R15AUD series mode surge filter / power conditioner. BPT (Balanced Power Technologies) BP-3 dual balanced power isolator.

post #2 of 86
Thread Starter 
Tomorrow I'll post some pics I took of these cables. Keep in mind that my digital camera is sub-par by today's standards, but still decent.
post #3 of 86
Thanks for your impressions of the 4 cables, great info. I must say I love the bright red color of the Clou (just like a bright red porsche) but these matters are individual taste.

The real issue I guess is since you can buy Senn 600 for $250 or less does it make sense to spend $150-190 for the connecting cable? (I am afraid I know what the answer is for me)
post #4 of 86
First, I'd like to represent Team Sennheiser HD600 and thank you jude for the relief we've all been waiting for. Excellent shootout.

I'm leaning heavily on the Equinox cable, however, I have a question to ask. Do you think that the Equinox would benifit at all if Cardas were to sell their proprietary earpiece plugs to outside cable builders and Stefan utilized them into say Equinox version2? Are there any side-effects of splicing? Oh and would the Equinox be suitible for portable use (light enough, flexible enough) as well? . BTW, 9-foot length is fine for me. I'd like to add that I'd opt for ¼" plug as well.

Also, could you post close up pictures of the earpieces of both the Equinox and the Cardas prototype?
post #5 of 86

Thanks for the excellent review.

However, it's just what I was afraid of. My wallet said "ouch" as soon as I heard that Cardas was coming out with a cable for the Senns
post #6 of 86
great review!

being in the market for some cables (once I get the money!) this has been very thought-provoking. I look forward to the pictures, that will probably be the decision-maker for me (I unfortunately have too many badly recorded cds!)

post #7 of 86
In his review of the Sennheiser hD600, Wes Phillips claims that "female singers" and "solo instruments" "tended to sound a tad distant throughout their lower ranges. ... In fact, wide-ranging instruments such as piano ... sounded slightly bigger and warmer than life in their lowest registers (a seductive additive coloration) and then sounded slightly less present throughout the midrange and presence region, before popping into sharp relief for their upper octaves and overtones."

Judge, do you agree with this observation? And if so, do any of these cables correct the situation?
post #8 of 86
Originally posted by shivohum
Judge, do you agree with this observation? And if so, do any of these cables correct the situation?
Judge. A Freudian slip? Actually quite appropriate here
post #9 of 86
Originally posted by shivohum
In his review of the Sennheiser hD600, Wes Phillips claims that "female singers" and "solo instruments" "tended to sound a tad distant throughout their lower ranges. ... In fact, wide-ranging instruments such as piano ... sounded slightly bigger and warmer than life in their lowest registers (a seductive additive coloration) and then sounded slightly less present throughout the midrange and presence region, before popping into sharp relief for their upper octaves and overtones."
This is what made me dislike both the HD580 and HD600 when listening through a number of headphone amps, including the Wheatfield HA-1, Holmes Powell DCT-1, Headroom Max, and Headroom Blockhead. When I heard about the new Cardas and Stefan cables (mainly the Cardas) and that the Cardas was more revealing and honest to the signal than the stock cable, I went out and purchased a used HD600. Should be coming my way soon -- can't wait for the Cardas to come on the market!

Judge. A Freudian slip? Actually quite appropriate here
Freud didn't wear no stinkin' dresses!
post #10 of 86

Thank you for a good posting. Very helpful. I was considering the Clou Red cable until I saw your posting. Can't wait for the Cardas cables to be available. I am basically a tweak freak and upgrading the cables for my HD-600 and HD-580 seems like the next logical step.
post #11 of 86
Judge. A Freudian slip? Actually quite appropriate here
Heh. Whoops.

Freud didn't wear no stinkin' dresses!
Lol. My sentiments exactly.
post #12 of 86
Freud didn't wear no stinkin' dresses!
I don't get it.
post #13 of 86
Very nice review, jude. Have you found any songs where the singer still seems too distant, no matter which cable you used?
post #14 of 86
jude, great review! I'm actually not even done with it yet, but I'll finish reading after my classes. I just wanted to point out what appears to be a sight mistake:
Cardas cable really manages to convey greater high frequency extension than any of the other cables, reaching in and scooping out treble information I had no idea my HD-600s were cable of delivering
an understandable mistake given the subject matter and a profound lack of sleep . that should be "capable" right?
post #15 of 86
I don't get it.
It's a pun on slip, where slip in one context means mistake and in another means a woman's undergarment.
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