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Superlux HD-668 B


Pros: impressive price/performance ratio, giant killer sound performance, removable cable, replaceable earpads.

Cons: isolation and sound leakage due to semi-open design, not a typical removable cable.

The product was provided to me free of charge by Gearbest (thank you @George-gearbest) for the review purpose in exchange for my honest opinion.

Manufacturer website: Superlux, Available from Gearbest.

* click on images to expand.



Even so I have been focusing lately on testing and reviewing flagship IEMs and CIEMs, majority of which cost north of $1k, in this write-up I’m going back to my roots and will talk about sone of the cheapest pairs of headphones I’ve tested to date.  Keep in mind these are full size semi-open cans, not another budget pair of in-ears or earbuds where I have seen even lower prices ($5 Monk being the prime example).  But still, at $35 or sometime even down to $30, I haven’t heard full size headphones that cheap with a sound that good!  Don’t mistake this level of excitement for “OMG, this kills any $500-$1k pair of headphones”, let’s be realistic.  But I have no problem saying these $30-$35 headphones have a build quality of other $60-$70 pairs and sound quality that can go head-to-head with a number of full size cans up to $200.


3+ years ago when I started writing my audio gear reviews, my focus was solely on budget earphones, trying to find the next Giant Killer.  But you can’t judge something to be a “giant killer” without experience of testing more expensive mid-tier and flagship “giants”.  Now, I made a full circle which gives me a more objective point of reference for comparison.  I also made an interesting observation about this HD668B model while reading various impressions since its release in 2011.  Many of the negative comments I read about it are no longer applicable to this 2016 version, which makes me wonder if Superlux already implemented some of the fixes and improvements based on the received feedback.


The ironic part of this write-up is that I wasn’t even planning to review these headphones and was asked to take a listen to them in addition to something else I requested to review from Gearbest.  I probably would have dismissed them just on the basis of how much they cost, expecting the usual of “you get what you paid for”.  But I was proven wrong, and now would like to share with you about my experience with Superlux HD668B after spending the last few weeks testing them.


Unboxing and accessories.


Unboxing experience of HD668B didn’t feel at all like I was dealing with a cheap pair of budget headphones.  A sturdy cardboard box with a nice cover image, a very detailed spec and a description of the design, and a complete list of accessories with corresponding pictures – the packaging box exterior already carried a message of the product being too good to be true for $35 price tag.  But as you know, the writing on the box could be just a part of the overhyped marketing, so without further hesitation I proceeded to lift the cover.





I was greeted with a set of full size cans neatly packed inside of a cardboard insert and other accessories around it.  With everything out, I was looking at a generous size soft nylon carrying pouch/bag, two extension cables, 6.3mm adapter, a peculiar cable clip, and a printed manual/guide.  The nylon pouch felt neat and durable, branded with Superlux name.  I consider adapter to be a filler, but it could come handy with full size headphones when used in a desktop setup.  The clip made sense once I attached the cable to HD668B, realizing it does a great job securing the joint if you pull on the wires.






Regarding the cable, it was actually an extension cord.  First of all, the whole idea of a removable cable in $35 pair of full size headphones is impressive.  But it’s not a traditional cable with 3.5mm male plug on each side.  To keep HD668B earcups slim, Superlux brought out the connector to the outside with a male 3.5mm plug and a very short extension cable.  As a result, you attach the provided “extension” cable to this external connector.  Included was 1m short cable, perfect for a portable use, and 3m long cable for other applications. You can also combine them together to form 4m extra long cable to give you more traveling room around the desk.


This "extension" cable idea was quite unique, though it would not be easy to find an extension cable with in-line remote if you need to.  But you can also argue that majority of people would prefer not to carry a phone conversation with these on.  With connector placed on outside, the earcup housing was definitely slimmer.  Also, the attached earcup connector cable is very short with a heavy duty shielding and impressive strain relief.  Not 100% sure if the cable clip was really necessary since the mating of the cable was already secure, but it never hurts to add another level of protection.




Design & build.


The first look at HD668B brought back the memory of my recent review of ATH-A2000Z with a similar wire-headband design and 3D-wings.  Honestly, I was expecting a flimsy plastic construction, but surprisingly found it to be not bad at all.  Starting with a headband, you have minimalistic design with a support of 2 steel spring-wires, assuming one carries a cable going to the connector on the left side.  I have an average size head, and it was a bit tight at first but loosened up after a short time of being stretched over the soccer ball.


There is no height adjustment like in traditional full size headphones, and instead you have soft foam “wings” on a spring metal wire which self-adjusts as you put headphones on.  This could be hit-or-miss with some people who have big head or curly hair (the last comment actually came from my wife).  For me personally, it works quite well since I’m already accustomed to ATH-R70x and ATH-A2000Z, both of which have a similar “wings” headband support.


HD668B next to ATH-A2000Z


Though the headband spring-wire felt solid, these wings felt a bit flimsy in comparison, especially a thinner wire attachment - just have to be more careful when taking these headphones off you head.  Closer to earcups, the headband wires are held together with a plastic joint piece on each side, kind of reminding me of “y-splitter”.  These pieces look to be replaceable, if needed, and made of a solid plastic material.  I found HD668B to be relatively comfortable to wear, and with evenly distributed 220g of weight it felt feather light.


Moving on to earcups, here Superlux took a page right out of AKG240.  I have no doubt that Superlux engineers were inspired by AKG design, even bringing the connector to outside, though keeping a standard 3.5mm TRS plug for “extension” cable attachment.  The back of earcups also has a similar to AKG circular vents, intended for a semi-open back performance.  The inner middle part of earcups does pivots to adjust around your head, and it works quite well.  The pleather earpads are easy to remove and to replace, especially if you want something softer.  Since the earpads look universal and stretch over the top of earcups, I’m sure replacement alternatives won’t be hard to find.


The included original pleather pads are OK, but they do get a little hot after extended use.  It definitely makes sense to experiment with different earpads to hear how they affect the sound.  Just like eartips of in-ear monitors, you can fine tune the level of low end extension and impact as well as being able to control the top end.  In addition, once you remove the earpads, you can also experiment with different dampening foam materials to figure out how it affects the sound.  Here you will find plenty of room for modding experiments.









The fit.



Sound analysis.


Before jumping into sound analysis, I left HD668B on burn in for about 100hrs, making sure their dynamic drivers are properly conditioned.  Honestly, I didn’t have too high expectations for these, still being a bit skeptical due to the low price.  As a result, my surprise was more shocking when I discovered HD668B to be tuned with a tasteful V-shaped full body sound signature and warm detailed tonality.


In more details, I hear a deep low end impact, down to a textured sub-bass rumble and a tight mid-bass which has a bit of a hollow punch.  The bass is rather well controlled, articulate, and there is no spillage into lower mids.  The lower mids have a nice full body, but there is no muddiness or congestion, while upper mids are clear and detailed with an organic presentation of vocals - not too much upfront, just pushed a little back due to an elevated low end.  Treble is surprisingly crisp and detailed, with a good extension, and some nice airiness which helps with layering and separation of instruments and vocals and contributes to higher resolution of the sound.  If I have to nitpick, perhaps upper frequencies have a little shade of metallic sheen, but it wasn’t that bad especially when you pair up with different sources.


Soundstage has a good expansion in width, not super wide but definitely way above the average.  The depth is not too far out, but you still feel like a few rows in front of the stage, giving a soundstage perception of spreading left/right around you without going too deep.  Layering and separation was surprisingly good due to well controlled low end which keeps the sound clean from muddiness without spilling into mids and extra sparkle in treble which adds some air between the layers of the sound.


If you are looking for a good isolation, these are definitely not the best for listening on the bus or in the library, after all - this is a semi-open design.  But it wasn’t leaking as bad when you step away 2-3ft.  I’m sure some will find this semi-open design even beneficial since it could raise the surround awareness without losing too much of the sound details.


Sound comparison.


Considering 98dB sensitivity and 56 ohm impedance, I found HD668B to be a little less efficient in comparison to my other headphones, and as a result I had to push the volume a little higher.  Also, it’s clear that more expensive headphones have an edge in build quality and material selection.


HD668B vs ATH-MSR7 - HD soundstage is wider, while MSR7 has more depth.  HD has a deeper sub-bass and a little stronger mid-bass, while MSR7 has a more balanced low end.  I also noticed that HD has a little faster attack of the mid-bass while MSR7 is a tad slower.  Lower mids are similar, while MSR7 upper mids are more forward, balanced, and a little brighter in comparison to HD.  I hear treble as being similarly crisp and well defined, though MSR7 has a little more airiness and a better extension.  Overall, the biggest difference here is a more balanced signature of MSR7 versus lifted low end and slightly recessed mids of HD.


HD668B vs ATH-M50x - HD soundstage is wider, while M50x has more depth.  HD has a deeper sub-bass while mid-bass is similar, perhaps with HD having a bit stronger impact.  Mid-bass speed is also similar.  Lower mids are very similar, while upper mids in M50x are more balanced and more forward in comparison.  Also, M50x upper mids are a little smoother and a touch warmer.  HD treble is crispier and has more airiness in comparison to a smoother M50x treble.  While I enjoy M50x comfortable fit for extended listening on my laptop, here I actually preferred the sound of HD.


HD668B vs SoundMagic HP150 - HP150 soundstage comes closer to HD width, but not quite there, and HP150 has a little more depth.  Also, HP150 sub-bass reaches deeper to the same level as HD, but a little shy of HD quantity, and mid-bass in HP150 is a bit lower in quantity as well.  HP150 lower mids are leaner and upper mids are a little more upfront and brighter with an advantage of slightly improved retrieval of details.  Treble is rather similar, being crisp, bright, snappy, and with enough extension and airiness to make the sound more resolving and layered.  Actually, after closer listening I hear HP150 being a little brighter in upper mids/treble.


HD668B vs Oppo PM3 - HD has more width and both have a similar depth.  HD has a deeper sub-bass extension and faster mid-bass punch with more impact.  PM3 mids sound more congested in comparison to HD, though they are more forward in presentation.  Actually HD upper mids are brighter and more detailed and the treble is crisper, better defined, and with more airiness.  PM3 has a very smooth laid back sound while HD has a faster punchier brighter and more detailed sound.




Pair up.


Note 4 – Pretty good pair up, though have to push volume closer to the max.  The sound becomes more balanced with a little less impact in mid-bass and a softer sub-bass.  But mids are still detailed and treble still has a great extension.  I also found upper mids/treble to sound a little brighter.  Good soundstage expansion.


LPG – here you will find a great transparent sound, deep extended sub-bass, punchy mid-bass, clear and detailed mids, crisp and airy treble.  Soundstage had an impressive width.  It was a great pair up, and I enjoyed the sound quite a bit, definitely giving HD668B giant killer stamp of approval while driving this pair of $35 headphones from this $2k source.


DX80 – I found a surprisingly balanced sound with mids a little more forward instead of pushed back, but I think this balanced sound sig change was due to sub-bass and mid-bass being scaled back a bit.  Very clear and detailed sound, upper mids are a bit thinner and vocals were not as organic anymore, treble is crisp, clear, and airy.  Soundstage was wide.


X7 w/AM2 – in this pair up I found sub-bass and mid-bass scaled down a bit, making the sound more balanced.  But it also felt like upper mids came a little more forward.  In addition, the bass was tight and punchy, clear detailed mids with plenty of body, and crisp airy treble.  Soundstage was wide.


L3 Pro – here the signature was back to v-shaped, with a good sub-bass extension and a nice rumble, and tight punchy mid-bass with a decent impact.  Lower mids have plenty of body, and uppers mids are clear and detailed but also a little harsh with a metallic texture and a touch of sibilance.  Treble is crisp, airy, extended.  Soundstage was wide.


AK120ii – in this pair up I found a little bit less sub-bass, still tight punchy mid-bass with a bit of a polite quantity, lower mids had natural full body and upper mids were a little thin, bright, and quite detailed. Treble is crisp, airy, extended.  Upper frequencies have a bit of a metallic sheen.  Soundstage expansion was pretty good.




I’m starting to notice a pattern where many of my “giant killer” discoveries happen by accident, when I’m not even looking for another budget pair of headphones and instead just asked to try something new for fun.  Did I get spoiled by flagships?  It’s hard not to, and I’m being honest about it.  But sometime it’s refreshing to take a step back and to listen to these amazing gems that cost so little.  From $5 Monks to $10 KZs and now $35 HD668B – these are all amazing discoveries that show you how creative a manufacture can get by challenging themselves to squeeze every ounce of performance and sound tuning on such a small budget.  HD668B is a real deal Giant Killer, and either if you are on a budget or just want to humor yourself with another budget discovery – I have no problem recommending these semi-open full size headphones because they don’t just look cool and ready for modding, but they also sound great!


Pros: great value, removable cable, auto-adjusting headband, super inexpensive price but really great sound for the dollar

Cons: treble might be a little enthusiastic for some, clamping force might be a little high for some





Superlux – the Chinese/Taiwanese company really doesn’t need any further instruction for anyone who is at least just a little into audio and headphones. Being in the business for over 30 years, the company is manufacturing microphones, portable PA systems, conference gear, monitoring systems and of course headphones.
Especially their headphones and also in-ears were very positively received by the audiophile community and headphone lovers for delivering exceptionally good value for the money and sounding good despite being so inexpensive. A large part of this “secret” is the abandonment of large (or any at all?) marketing and ad campaigns and re-using the design of existing products.
Less commonly known, Superlux also acts as OEM manufacturer from time to time.

I jumped on the Superlux train quite late – it must have been around spring of 2013 or 2014. That’s when I thought it could be fun trying such an inexpensive circumaural headphone and therefore bought the Superlux HD681.
Not expecting much, the ~ €20 headphone surprised me a lot and delivered anything but a cheap and unrefined sound – yeah, it was actually quite enjoyable and sounded like it cost considerably more. Based on what I heard, I wouldn’t have hesitated to spend ~ €70 for the sound and likely even more if the treble was somewhat less forward and more even.

I also shamelessly admit that I reached out to Superlux not too long ago, asking if I could test some of their other headphones, but didn’t hear back from them at all.
So when George from GearBest recently reached out to me and asked whether I was interesting in getting a sample of the Superlux HD668B (http://www.gearbest.com/headsets/pp_279992.html) free of charge for the purpose of an honest, unbiased review, I didn’t turn down the offer but actually happily accepted it.

Technical Specifications:

Price: $25.99 (http://www.gearbest.com/headsets/pp_279992.html)
Type: circumaural, full-sized, (semi-) open
Drivers: 50 mm, dynamic
Frequency Range: 10 Hz – 30 kHz
Impedance: 56 Ohms
Sensitivity: 98 dB

Delivery Content:

Oh man!
Unlike the HD681 series, the HD668B arrives in an actual cardboard package that is even quite nicely designed and carries information about the delivery content, technical specifications and has got a couple of nice pictures of the headphone and its accessories.
Opening the package, I was even more surprised to find a manual, 3.5 to 6.35 mm adapter, the typical Superlux carrying sleeve, the headphone, no less than two cables (a short 1 m and a long 3 m one) and a clip to safely lock the cable.
At less than $/€30, that’s definitely not what I would have expected but extremely nice to see.





Looks, Feels, Build Quality:

The HD668B looks like some other Superlux headphones and also features an automatically adjusting headband that is definitely inspired by some of Audio Technica’s models.
There are side markers and the cable is attached to the left side which is pretty much the industry standard for one-sided cables.
The small piece that protrudes is a 3.5 mm jack, so instead of the included cables, one could also use any other cable extension with a 3.5 mm socket.
Strain relief is good on the cable itself and sufficient on the protruding piece and feels relatively sturdy and is adequately flexible.




The idea of the small clip that guarantees for a secure connection between the cable and the protruding piece is a quite clever idea in my opinion.


As expected and known from other Superlux headphones, the entirely black headphone is made of plastic but isn’t too badly built at all and appears sturdy. Only the pleather pads’ stitching looks a bit cheap, but that’s what likely most of Superlux’s headphones have in common (including my HD681).





Comfort, Isolation:

The circular ear cups swivel and therefore adjust to one’s individual head shape. The idea of the self-adjusting headband is also quite nice but I personally somewhat prefer the even pressure distribution of the HD681’s headband to the HD668B’s which distributes the pressure mainly to the sides of the top of one’s head.
Talking about clamping force, due to the headband but also in general, clamping force is on the stronger side and the HD668B sits definitely tighter on my head than my HD681. I don’t have a problem with that and also don’t mind my Sennheiser Amperior’s clamping force, but those who are sensitive to this might find the HD668B a little uncomfortable or tightly fitting after extended wearing periods although the pads are actually quite soft.
Microphonics are by the way pleasantly low even when using the headphone when walking.



With my HD681, I was quite surprised that it had something that could be called slight noise isolation, and with the HD668B, I can also report that there is a little bit of isolation, but it is not much at all and doesn’t mask my keyboard’s or the fan’s noise although noise isolation is very slightly more present with the HD668B than with my HD681, probably because of the stronger clamping force.


In case anyone of you is wondering about the last letter of the naming scheme of Superlux’s products, it is quite simple: of each product type, there are three iterations that differ in bass quantity. The one without any additional letter has got the most amount of bass, the one with a “B” at the end is right in the middle (“Balanced”) and the one with an “F” at the end is the one with the least amount of low-end emphasis (“Flat”).
So the HD668B sits right in between the HD668F and HD668 when it comes to bass quantity.

Just for your information, I am wearing rather bushy mutton chops at the time of writing these impressions (actually even a full beard at the moment), so the perception of treble might slightly vary for you if you are either mutton-chop-less or bald.
That facial and scalp hair has some effect on the treble is what I once found out in an experiment on myself when I shaved my entire head and face (I’m not sure about my moustache though, but of course it doesn’t matter for that) in order to find out whether my perception of my Sennheiser HD 800’s treble changed – but that’s an entirely different story.


The HD668B is a v-shaped headphone with a present upper bass punch, somewhat recessed but not sucked-out however slightly bright mids and a forward middle as well as upper and super treble.

The bass stays out of the mids and starts climbing from around 500 down to 100 Hz where the climax is reached with ca. 7.5 dB north of neutral and has a subjectively perceived strong impact. It doesn’t start rolling off until 60 Hz, so there is still a good amount of midbass and even some sub-bass although there isn’t that much going on anymore below 35 Hz.
As mentioned, the lows stay out of the mids really nicely. Speaking of the latter, they are a bit in the background and somewhat on the leaner, brighter side wherefore vocals sound a little brighter than what would be neutral.
Above 1500 Hz, the treble starts climbing, takes a small dip between 4 and 5 kHz and then rises even more, reaching its brightest point around 11 kHz although the rest below is definitely on the bright side, too. Above that, the highs don’t take a step back at all and maintain this amount of treble sparkle even past 17 kHz.

Overall, instruments and vocals don’t sound coloured by much besides the upper treble that makes cymbals sound somewhat metallic and unrealistic. Instruments like trumpets that play in the lower treble do however sound realistic. Vocals can sound a slight bit sibilant from time to time but it is nothing striking and I think the small dip in the middle treble around 4.5 kHz helps with that a bit, as the HD668B sounds a little less sibilant than my HD681.


No hype here, as you definitely shouldn’t expect a headphone that can fully compete with decent models above $150 or even $100 in every discipline, but to come very close.
However, for the little money the HD668B costs, you get a really good overall package, and just as with the HD681, I wouldn’t mind paying more than $70 for the sound quality alone, but just as with the HD681, the treble can be too forward and edgy at times and/or could be more detailed/better layered in order to keep the emphasis but not to sound somewhat obtrusive.

The bass isn’t slow at all but feels a bit soft and is not the most detailed or cleanest and sounds a little blunt, however I have a hard time realising that a headphone this inexpensive is producing a bass that has got definitely better speed and control than I would expect at the price point.
The mids don’t sound grainy or lack details at all and are pretty nice considering the price.
And while the treble doesn’t reach the separation and details of more expensive headphones, there is really nothing wrong with it at all although it would have probably sounded even more pleasant if either the upper-end resolution was a little higher or if it was less forward.

If you are familiar with some of the trash that you can buy for less than $30, you should easily hear that the HD668B is nothing like those models but sounds really decent for costing so little.


The soundstage is on the smaller to average side with almost as much spatial depth as width. Regarding size, it is circa as wide as the space between the ear cups and stops around where my eyes are located.
It is not the airiest soundstage but good overall and while instruments aren’t as cleanly separated as with more expensive headphones, they aren’t too blurry and don’t blend into each other by too much.
Regarding price, the soundstage is even quite good when it comes to precision although I couldn’t precisely make out two instruments that are very close to each other.


In Comparison with other headphones:

Superlux HD681:
The HD681 does definitely not really appear weak on the bass at all but the HD668B is the audibly bassier headphone. The HD681 extends slightly better by ca. 3 Hz which is not much and only audible when doing sine sweeps.
In the mids, the HD668B is slightly less bright than the HD681.
The HD681’s treble is more forward, brighter and more obtrusive and has got no slight dip in the middle highs, hence the HD668B is easier tolerable in the highs out of the two.

Regarding bass, the HD681 appears a little cleaner, less grainy and more detailed, but really not by much.
In the mids and treble, both are more or less on the same level with the HD681 only sounding airier because of its tonal tuning. The HD681’s treble is probably a slight bit cleaner however it is more aggressive as well as edgy.
Overall I would say both are pretty much on the same level with just a different tuning.

When it comes to soundstage, both headphones sound almost identical to me. The HD681’s might be a little wider but if this is really the case, it would be less than 0.5 cm.

Overall, it’s pretty much a draw with the HD681 having the slightly cleaner bass and the HD668B sounding more tolerable and less edgy in the highs.

Fostex x Massdrop TH-X00 (Mahogany):

Although both headphones are playing in a (totally) different price and sound league and one is (semi-) open and the other is (semi-) closed, they still have some things in common.

For once, the Fostex doesn’t isolate well at all for a closed-back headphone whereas the Superlux has got some isolation although it is open. Besides that, both sound v-shaped, are using dynamic drivers and offer really good value, both at their respective price points.

The bass starts about similarly extending on both headphones until 100 Hz with the Fostex being a little less full in the root, but below, the TH-X00 continues to climb and starts rolling off much later, so it has got considerably more sub-bass and midbass, making it more engaging and fun sounding in the low registers.
In the mids, the Superlux is the somewhat brighter and leaner sounding headphone.
In the lower and middle treble, the Fostex is less present and even slightly recessed in the presence range, hence vocals don’t sound sibilant or bright at all but tonally right to the point. And while the Superlux is the brighter and thinner sounding headphone in the highs, the TH-X00 has got the somewhat more present area around 12 kHz to my ears but sounds overall considerably more natural and realistic.
Overall, the TH-X00 has got the better made and more realistic v-shape so to speak.

You definitely won’t see me ever writing that both are playing even slightly in the same league but you also won’t see me writing that the TH-X00 totally smashes the HD668B and runs circles around it although the Fostex is better in about everything by a good bit and has also got a much more premium build quality. In fact though and realistically speaking, on the sound side, the TH-X00 is definitely even far away from being five times better than the Superlux but is still playing in an easily audible higher league.
When it comes to the bass, the Fostex is cleaner, more arid, tighter, better controlled as well as better layered and reaches deeper without softening towards the sub-bass. In the mids, it sounds more realistic and layered, and its treble is more detailed and refined as well.
In terms of soundstage size, both are about comparable although the TH-X00 feels a bit wider and deeper. When it comes to spatiality though, the TH-X00 is audibly better separated, generates more air and empty space arounds instruments and creates the more authentic imaginary room. It also doesn’t collapse with fast and busy music.

In my opinion, if you cannot/don’t want to buy the TH-X00, want a cheap backup or really cheap alternative that doesn’t sound like total crap but relatively decent for the respective price, the HD668B could be a really solid choice if you can let go things the Fostex’s deep bass extension or resolution and if you can live with a forward, sometimes somewhat overly-bright and edgy treble. Switching from the Fostex to the Superlux, while the latter is inferior in about everything, I however don’t screw up my face or want to throw up, which is a really good sign.


Less than $30? Indeed. For this little money, one gets a really decent headphone that could easily cost twice or three times as much based on the pure sound, but please don’t expect the HD668B to blow away some of the better headphones costing more than $100/150 or to be on-par.
And even though the headphone is strong on the technical side and still so cheap price-wise, it comes with a nice selection of accessories and a really nice package design.

The sound is more on the fun and v-shaped side with mids that are just slightly brighter than neutral and a treble that might be somewhat too edgy, forward and bright for some, however this bright treble is the only thing the HD668B does “bad” when it comes to tonal tuning. Besides the ambitious highs, it sounds overall remarkably natural for the price and above.
And in terms of resolution, while it is not perfect and sounds a little grainy in the bass, the HD668B plays definitely in a higher class than what you pay for.

On the bad side, we have the bright and sometimes too edgy treble that is definitely nothing at all for people who like to listen at rather high volume levels (not me) and the clamping force that might also be a little too tight for some.
On the good side however, there are so many things sound-wise for the price and even without knowing the price tag.

I am not 100% sure whether I should make this a 4 or 4.5 star review, as the HD668B is sitting somewhere in-between. Neglecting price and value, it would be a 4+ star product in my book, but including the value as I always do in my ratings, this headphone scores easy 4.5 out of 5 possible stars.

Yep, it is quite remarkable that Superlux has created a couple of headphones that don’t sound like the usual trash you would probably expect for such little money.


Pros: dynamic, deep bass, relatively balanced, analytical, good soundstage, very inexpensive

Cons: slightly recessed lower mids

I won´t repeat what everyone else wrote before - because it´s true. I´ve listened to a Beyerdynamic DT990 once and while I love my Sennheiser HD-600 a different cup of tea would be nice sometimes. But then, Beyerdynamic headphones are a bit too expensive for the sole reason of being able to listen to "another flavour". Thank God there is Superlux. You´ll get so much material for your money. You´ll also get very good, Beyerdynamic-like sound. You can even improve the sound if you replace the pleather earpads with the velour pads for the AKG K-240. I don´t know why but they sound a bit more balanced and refined with these earpads. Further improvement can be achieved by putting paper tissue between earpad and cup (increases the distance from ear to driver and will likewise improve comfort).


If you do these two things you´ll get a headphone that will rival headphones for 150-200 Euros: they are dynamic, precise, crisp, balanced with a very good soundstage. They are easy to drive but they will sound best with good amplifiers. They won´t be impressed by loud or harsh music, they will just play along with just the right amount of directness. Some people would argue that this makes them sound a bit "bored" - which sounds almost insulting to me because they are anything but boring. People seem to confuse balanced sound with boredom. Well, let me put it this way: if you want your headphone to colour the music you´re listening to... go and search elsewhere. The Superlux does indeed add a bit colour (around 7.000 Hz) but it´s not very much and it´s not distracting. However, lower mids seem to be a bit underrepresented - but I could be fooled about that because I´m accustomed to the comparatively (to the Superlux) warm mids of my HD-600.


All in all, very, very good for the money. A true bargain, thank you Superlux.


P.S.: before I forget... they need considerable burn-in time to sound their best.


Pros: Neutral, revealing, precise, lightweight, sturdy, cable features

Cons: Strong clamping force (gets better with time)

As the saying in the title goes, this has never been truer than for these headphones.

Thankfully, Superlux sells sound quality, not an overhyped brand name. Can you really get great sound for $40? Oh yes, and it's right here.


I was recommended these headphones by a fellow forum member and after a day or two of investigation I decided I really liked what I read about them and figured if it was true, then these would be the best headphones I could buy on my really limited budget. So, I did.


Before I give any impressions, a small disclaimer: My previous headphones were Trust HS-6200 5.1 USB, and Trust Multi Function Headset 310. The most "hi-fi" component I have in my house is a set of Logitech Z-5500's. They run via coaxial, while everything else runs from the motherboard Realtek ALC889 codec (best Realtek codec, but still onboard.) So, I have not had much experience with quality components, but I know how to trust my ears. Hopefully, this will be enough to make a relatively accurate assessment of these headphones. Let's take it from the outside in.


Design: Well, the first thing that surprised me is that they are relatively small. I expected them to be a bit larger from the pictures. The next thing is, they are really light, weighing only at around 200 grams, which is good as it makes them easier to keep on the head for longer periods of time. The build is fairly sturdy and the plastic is of good quality, they look like they will last long. I'm not going to comment much about aesthetics, aside from the "Studio Monitor" labels being a bit tacky, but I generally like the way they look.


Comfort: A bit on the tight side. Causes my ears some discomfort after having them on for a while (upwards of 2 hours), but after a few minutes break it's good. I've read some people claim it made their ears sweat and heat up, I haven't had those problems but I don't normally sweat much anyway.


Accessories: With these headphones you get a 3m cable (for PC use) and a 1m cable (portable use) which you can exchange and even combine together. You also get a 3.5 (1/8") to 6.3 (1/4") mm jack adaptor, which is a nice feature, and a carrying pouch to, well, carry them around.

I liked the cable flexibility the most, I think it's a great idea.


Sound: And here we go, the most important part. I'll try to refrain from analyzing these headphones in the typical fashion here such as how the "highs, lows, mids, etc." sound as I don't think I'm familiar enough with the terms here but I will attempt to describe their overall sound signature with my limited experience, so here goes. What you play through them is what comes out. A bad recording will sound bad, a good one great. They are really transparent, simply "passing on" the sound without leaving a hint of presence of their own. And honestly, I like this. I want to hear my music the way it was recorded, intended to be heard. I don't want headphones to change my music. Sure, colored headphones may make it sound more "fun", but that's not the way the artist heard or made the track. Well, to each his own I guess. To continue: they reveal a lot of detail. A lot. Background hiss, noise, breathing, coughs from artists and stuff I have never heard before in my music. I have to play through everything again, to rediscover all those tiny details I missed out until now. The frequency response doesn't have many spikes, and it corresponds with what you can see on the manufacturer's website.

Soundstage, well, it's generally good. Certainly better than the closed-back headphones I own. These are only semi-open however. Sound isolation is still OK, I can hear myself typing and my noisy PC case, but when music plays it's hardly audible. To sum it up for the Superlux HD668B: Add nothing, reveal everything.


Oh, one more thing: the bass. I've seen a lot of people claim the bass isn't strong enough, while a few claimed the bass was good. And I believe I know why. It actually depends where you plug them in. If I plug them into my PC case's front port, the headphone out on the Z-5500, my cell phone or MP3 player, the bass is overwhelming, in fact there is more bass than there is in the 5.1 headphones that had a dedicated subwoofer inside, and it certainly does not sound natural. However, if I plug them into the rear ports on my motherboard where there is supposedly a headphone amp the bass tames down by around 80%.


EDIT: After a bit of longer listening, I've realised that it's not the amount of bass that changes. It's the amount of mids and highs. The thing is, the output ports on the back of the motherboard are assignable. If I set the jack to "speaker out" they give a line level signal, and the headphones sound substantially less clear and you have to turn the volume up from 35 to around 80; this gives the impression that the bass is louder - it's not, it's only that the signal is not strong enough to drive the mids and highs up to point. When switched to "headphone" setting, the headphone amplifier kicks in and the higher frequencies -really- jump up, leaving the bass behind at the "normal" level. This is why it seems it has less bass. So even though these headphones are only 56 Ohms, they certainly benefit from amping, and well at that. Line-level won't cut it.


Overall, I am extremely happy with them, will keep them around for a long time. My next purchase is going to be an Asus Xonar Essence ST, I can't wait to hear what they will do then. Well worth the money I paid for them and more, and would recommend them to anyone in this price range, for sure.


Pros: Neutral sounding :-)

Cons: Neutral sounding ;-)

I recently got these headphones from a german online store after reading the raving review at headphonia.com. While it left me quite sceptical, I thought ca. $35 isn't that much of a risk to take and they'd even be worth the price if they just had a decent sound quality.

But they haven't. They have an incredible sound, just like the reviewer at headphonia and the previous reviewer here have described it. They are very detailed, very much extended into both directions of the frequency spectrum and sound just wunderfully neutral. The highs are brilliant but not shrill or sibliant, the bass is punchy but not muddy and overwhelming, the mids are tight and precise - it's just everything there as it should be, nothing added and nothing left out. If you prefer a more coloured kind of hi-fi sound like the Grados are known for, these cans aren't for you. If you prefer a neutral, "honest" kind of sound, I doubt you'll get any better cans below $200. Personally, I love the synergy the Superlux show on a crossfeed. It "warms" up the sound just to the right amount, giving a slight boost in the bass and further refining the headphones convincing soundstage. I prefer that combo to most much more expensive headphones I know.

The only thing, however, that constantly reminded me of wearing a headphone was the pressure of the pads, which made my earlaps hurt after an hour. I solved this problem by adding a little spacer (made out of paper tissue...) to the back of the earpads. Considering the headphones quality it would also be worthwhile to replace the "pleather" earpads with some higher quality AKG ones.

Another detail I love about this cans: they come with two sturdy, detachable cables (1m and 3m, combined 4m) to ideally suit your needs. Great idea!


Pros: (in context of price) detail ,resolution, soundstage, fast-taut bass

Cons: (in context of price) bright ... bright ... bright

Got 2 pairs for US$65 ... gave one to a friend who is a bass-head (plays video games and runs it through movies [ DVDrips]) and kept one for myself.


After a year, here is our skinny on these El-cheapos:


Get the ugly part out of the way --> These boys are unforgiving and bright and WILL show up your crappy music systems. If the recording was brightly mastered/crap, if your source is bad, if your cables are bright (esp. pure silver and silver plated stuff), if your amp/dac setup is too revealing THEN these babies are RUTHLESS. They will show up the brightness and amplify the crap out of the brightness to make ears bleed.


No .. they will not flatter anything. They just let you know something is really amiss in your chain of music production.


Hence: although easy to drive (low impedance, high sensitivity), these are NOT for badly ripped MP3s, not suitable for porta-ipod/phone/mp3 players and not for your cheap PC music cards.  Forget it, you will get better sound elsewhere. You have been warned!!


Now for the honest truth about these phones - look carefully at the reviews. The folks who have a decent setup, and putting thru good quality sources (properly done CDs/FLACS/SACDs --> decent DAC --> decent amp) all enjoyed them, or were smitten by their price/performance ratio.


They may not beat the big boys costing 5-10X more in price (certainly not the Denon D5000 or the Grado PS1000). But unlike the other cheap crap in the sub US$100 range, they don't get worse as you up the ante, they get better - and better to the point of lunacy. No cans priced US$ 30 should be giving owners of Senn HD 600/Denon D2000/AKG 240/Grado 125 (Yes between my friend and I, we have had all these for extended periods in the past) raised eyebrows ... but this one does.


Yes its still slightly bright, and its bass doesn't extend low enough, neither is its midrange meaty and alluring enough ...BUT ... it IS still impressive for US$ 30.


Its best you treat these as studio monitors, as they were intended by their creators. But if you ever want a really ruthless pair of cans to weed out a weak kink in your setup, then try these out. If your systme boogies on these baby, then you can try out any other more esoteric headsets and have something to smile about.



















Pros: Price, awesome sound quality for the price.

Cons: Bright and recesed mids

After a year with this amazing cans i think i can say a couple of things.


How the hell they can make this cans for this price?? China it's the answer...




This cans are amazing for only 20€, they do an unexpected sound quality for the price. It's not a Giant Killer but it's a Mini Giant Killer (MGK), i own a Sennhesier HD555 and -for sound quality- the HD668B are at the same level no doubt, but for 1/4 of the price. 

If you like the music and want to experiment audiophile sensations but haven't soo much money i can't imagine better 20€ on sound equipment. 


Audio Quality:


Taking appart the price and forgetting the price to loose the Hype i must to say that his quality sound it's good, at the same level of cans with my HD555. Differents sound signature but same quality level .


The very best sound of this cans cames when we burn in about 200-300 hours, recesed mid came more forward and don't miss it soo much, and the initial bright blows up a bit but don't dissapears. At his 56ohm and sensivity is not a requisite amplifier the HD668b to make it sound good but an amplifier make it push his best sound, resolution, instrumental separation, etc.

In other words they are more Mini Giant Killer with a good amplifier on the way.


It's supposed to be balanced cans for the B on HD668B but it seems to me it's not balanced flat, it's balanced on "V" like the Beyerdynamic DT990 -on the superlux website it's frequency response it's compared and it's very similar-, soo take in mind that, this cans aren't Flat at all.


This cans are very analitycal, very detailed with envolvent sounds and with a very good soundstage, all this make rediscover new things on music you use to listen; little sounds that wasn't before but appear with them, it's a good sensation rediscover your old music on it.

They are very transparet on the recording quality sound, if you find distorsion don't blame on cans, blame on bad recordings and mastering studios or the bad music quality music you heard. Most pepople says this cans are bright and i think it's beacause of it, if the recording it's bright the HD668b make you to know "screaming" to you :)


The bass its well extended and present, maybe a bit muted on the very low frequencys (20-50HZ) but much more present on middle low frequencys (50-150hz) and with a very funny punch on it. Many people will found it  short of bass but i think its the perfect quantity to feel it real and not overbass.

I found the punchy bass very very funy and enjoyable on it. But without amplification dont expect miracles... 


The mids are a bit recesed at first but after 200-300 hours it came a bit forward and you don't miss it anymore, unless you like very forward mids in that case you don't like it. They are very well balanced after the burn in, very detailed, with clarity and natural.


The highs are very very good for me -but i like crispy sounds!!-; some people found highs very very present on this cans and don't like it for this reason, it's a point to have very present on it. I think that the  bright highs dissapear a bit after the 200-300 hours of burn in but always be there.


The "timbre" it's not bad at all, is not the most realistic -my Sennhesier HD555 have a more crystalline "timbre"- but i like it soo much on cord instruments and female voices and acoustic concerts. Maybe not as realistic as my Senn but much more fun and enjoyable.


A good amplification cames to life many many things to this cans and make it a lot of better, don't miss this point. Not soo much ohms on the way but with his sensivity (98 db SPL) a good amplifier change many things.




Nothing to say that you couldn't see on the photos. They are a copy of AKG on design and Audio Technica on headband pads. They are really light, lot of plastics every where, but well built and support hard treatment on it without broke it. Mines has fall down many times to the floor and still survive!!!


The pressure on the head maybe its a bit hard to support many time continuisly on the head and hurts but with time it take the form of your head and will bee more confortable, but it's there.


The most criticable thing on this cans it's the ugly earpads that would you sweat on summer like an idiot, and maybe Superlux would take the point for next models... :)


They have a cuple of cables (1m and 3m), one jack adaptor 3,5mm to 6,3mm and a clip to swich with no problem the cable to headphone that it's a new great idea rom Superlux and would must copy other brands.




This it's a good cand, a very very good headphone for the price, i can't imagine a better 20€ expended on  sound equipment.


Pros: Cheap

Cons: Sound

The sound is nothing like great bang for the bucks read in the reviews on forums. It's rather cold, thin, dull .. On any genre, from DnB over Guitar Rock to Classical music. These earphones are no fun at all.

If I had to pin it down, I would say this:
The worst thing about these headphones is that they offer zero "stage" and so little "detail" that it doesn't make sense for to listen to any good music with them.

I'm not trying to be the "against" guy here, because as you can see, it has so many good reviews, but in comparison to my old Philips (which died just before I bought the Superlux), the 668B are just a huge disappointment in every regard.

It's like changing from a Ferrari to a Fiat - Somehow the same, but not really -.-


Pros: Sound quality - Soundstage - Transparency - Overall neutrality - Clarity - Light weight

Cons: Somewhat piercing highs - Uncomfortable stock ear pads - Strong clamping force (gets better with time)

I got the Superlux HD668B as a gift from my brother. These were my first better than average headphones, and boy, they are good!


The build quality is quite good. It is sturdy and flexible, with a removable cable.

They come with a short cable and a longer cable, a quarter inch adapter and a nylon (feels like nylon) carrying pouch.


As for comfort, it isn't that good at first, as it has quite a strong clamping force, but it does get better with time. After a while, you can't even notice you're wearing them.


The sound: The first time I listened to them I was shocked how transparent and clear the sound is, with somewhat piercing highs, but good punchy bass and neutral mids. I let them burn-in for about 130 hours, and noticed that the sound opened up a little. The highs became less piercing, but still very prominent. The bass acquired more punch and depth. As for the soundstage, I can say they have excellent imaging for a sub 50$ pair of headphones.


Superlux must have mistyped the price on them. Must be that, because they are an amazing bang for the buck.


I do highly recommend these if your are looking for budget headphones with great sound quality, soundstage and imaging.


Pros: Stunning clarity and balance

Cons: Comfort issues, build quality feels cheap.



I chose to review these with my FiiO E7 with my E3 LOD to my iPod Classic as they definitely need some juice. The E7 is able to power these to comfortable listening levels though without a worry.




The Superlux HD668b came packaged in a rather cardboard box which I actually found to be pleasing to look at on the front. It's not eye catching, but it doesn't need to be. It simply says Superlux on the front with the model number and "Professional Studio Standard Headphones," with a picture of the HD668b taking up the rest of the space. On either side of the box the included contents are shown with many languages present to tell the information. The back has technical specs in various languages with a serial number and contact information.


The packaging isn't flashy, but I actually really like it. It is classy and old school and has a charm about it I really like. The box is also rather thick cardboard, it doesn't feel cheap. 


Inside is an instruction manual, the Superlux HD668b headphones, a cloth carrying pouch, a 3m cord, a 1m cord and a 1/8th to 1/4 adaptor. Nothing excessive, but well packaged. I'm happy with the included items and couldn't really ask for more.


Design and Build Quality


When I read some reviews on these I thought they looked beautiful, a nice mix of Audio Technica and AKG. When I received them I noticed the pictures were very flattering, it's not that the Superlux HD668b look bad in person, it's just easy to see that they are rather cheap looking. They still look fantastic, but the plastic and rather cheap construction is apparent.


The feel of these is rather cheap plastic with faux leather pads and thin metal wires as opposed to the thicker ones on the Ad900. For $50 though I can't blame Superlux, they obviously can't spend a huge budget on the quality of materials in the way Audio Technica can, especially when they're focused on the sound. Overall though, while they look cheap, I don't see any problems with durability. The removable jack on the left earphone is a nice touch, 2.5mm female plugs into the headphones. The cable is a bit thin and cheap feeling, but there's no problems I have with it sound wise or durability wise so far. I will say that I wish Superlux included a medium cable as the 3m is a bit too long and the 1m is a bit too short. I like that it terminates into a straight plug though.


When worn they do get a bit hot, despite the semi-open design, which really feels like a closed design and offers decent isolation. The pads do get a bit hot and there's some clamping which has cause my listening sessions to be kept around 1 hour or so. The clamping isn't huge, but it's definitely apparent. Overall though they feel decent on the head, I'm simply used to open headphones, noticeably my Ad900 which are amazing in comfort.


Overall I feel like Superlux did a good job with obviously a small budget. They feel and look good for the price, but it's apparent they had to skimp somewhere when compared to my Audio Technica Ad900.


Sound Quality


I really couldn't believe my ears for these. I let them burn in for 30 hours as Kevin at Superlux has informed me and put them on. "Wow, these cost how much?" Was my initial reaction. The sound is fantastically balanced with amazing clarity and a natural sound, that rivals my Ad900. While these are labeled as Studio Monitors don't let that fool you, I'm having a lot of pleasure listening to these, they aren't as music as my Ad900, but are more musical than my Ad700 and HD558. The bass extends well and has a nice full warm sound, it does lack impact though for electronic music such as drum and bass. The lows do leak a little into the mids a bit, but only so slightly as to make them sound a smudge recessed. The mids are full sounding with excellent clarity. They don't have the forwardness my Ad900 have, but they do a wonderful job for rock music regardless. The highs are a little tame, but they extend well. By tame I mean that they aren't piercing or overly bright. They still extend well with excellent clarity. The soundstage is great, it's not as big as my Ad900 or Ad700, but it definitely gives the music some room to breathe. Time to listen to some tunes!


Modest Mouse - Doin the Cockroach


While this song is admittedly lo-fi, I chose it because of it's quick pace and distorted guitars. The bass line is something I don't think I've ever heard properly, in-fact on my Ad900 it's barely noticeable. On these I hear it wonderfully, without it muddling the mids. The vocals and guitar sound wonderful. The vocals sound astoundingly natural, the guitar is able to be easily picked out through it's hazy distortion and sloppy playing. The headphones are able to keep up with the tempo no problem. Everything honestly sounds absolutely wonderful and natural on these.


James Blake - Limit To Your Love


The vocals and piano sound wonderful on these, absolutely wonderful. The notes ring out with a nice naturalness and clarity, nothing artificial sounding here. The heavy bass definitely extends well, but there's no rattling in my ears. I hear the bass and the headphones are able to keep up with the quick pace, but there's no feel of it. These definitely aren't for bass heads, but they do reproduce the lows wonderfully without muddling up the rest of the frequencies in this song.


Feist - I Feel It All


I chose this because it has a lot going on and is a nice sibilance check. The drums, acoustic guitar, tambourine, electric guitar and vocals all sound wonderfully natural. There's no hint of sibilance, which is fantastic. This song is a good test for sibilance and the HD668b pass. Feist's voice simply sounds wonderfully silky smooth.


High Contrast - Return of Forever


I chose this liquid DnB track to see how the Superlux would handle a fast paced song. The song has a nice balance in it. The repetitive bass line sounds right where it should be, the quick drum beat is sound as it should it doesn't feel slow or bloated and the miscellaneous sounds are easily apparent. I definitely like the HD668b for electronic, though I feel the Ad900 have a little more impact than the 668b making me choose them for dnb usually.


Rolling Stones - Sympathy for the Devil


This song has a lot going on in it, a lot of instruments. The various hand drums and shaker sound wonderful at any part of the song and remain a strong backbone for the rhythm of this song as the bass piano and vocals come in. The song sounds very natural and no instrument sounds more present than the next, at any point of this song I'm able to easily discern an instrument from the next. I'm very impressed for this song.




While the build quality and comfort isn't superb it's definitely more than average for the price from my experiences. The build quality is about on par with the Audio Technica Ad700, for instance. The looks are fantastic, I love the AKG/Audio Technica hybrid look. The detachable cable is also a very nice addition. The sound quality is superb with these, they easily rival $100 headphones and I find myself reaching for them over my Ad900 at times, they completely make my HD558 obsolete in my opinion, I'll never reach for them again.


If you're looking for a cheap, good looking headphone with excellent sound quality to price ratio look no further. The only problem you'll run into is finding a place that stocks these.

Superlux HD-668 B

Superlux HD-668 B studio headphones, dynamic, semi-open, 98 db SPL, 56 ohms, 10-30.000 Hz, 300 mW, self-adjusting headband pads

Model Name/TypeMPNEAN/UPC
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