Superlux HD-668 B

I have written a review in danish at the danish head-fi-forum, which is called Hoved-fi.dk, and I'll now do my best to translate it into english:

I have on a few occasions heard of Superlux, and that their headphones, despite being low cost, aren't the worst one can buy.

A few days ago, I had the opportunity to buy a pair of HD 668 B's for what equates to roughly 21.50$, including the cost of shipping and a pair of velour earpads.

Naturally, before recieving the headphones, I had seen quite a few written and video reviews of the HD 668 B, but since I do not seem to share sound preferences with a whole lot of reviewers, I am never quite sure what to expect from a headphone.

Finally: The arrival of the HD 668 B's! I removed the stock "leather" pads without even trying them with the headphones, as all of the reviewers mentioned that the stock pads were awful. The velour pads are very comfortable, and because the headphones weigh next to nothing, they are also comfortable for longer listening sessions.

The build quality regarding the rest of the headphone can best be described with the words: "You usually get what you pay for"

Except for the headband and the holders for the "wings" that rest on your head, the headphones are made of plastic. They dont squeak or rattle when handled, but apart from that, there aren't many more nice things to say about the build quality.

Not that they are going to fall apart with everyday use, but on the "nice-materials-scale", I'd give them a 2 out of 10 - because there at least is some metal included in the construction.

The headphones are sold with (I believe) a 10 foot and a 3 foot cable. I got mine secondhand, and only got the longer of the two cables.

The cable is rather thin, but is at least detachable, so if you happen to step over the cable, it should just come right off - if not, the cable can be replaced as described.

The 668 B's make use of what I'd describe as "wings", that rest off the top of your head, and prevents the headphones from sliding down. The concept is fine, but you might have to bend the wings (carefully!) a bit, in order to adjust the clamping pressure on your head.

The sound:

I have owned a pair of Hifiman He-350, that I'd - before owning the 668 B's - describe as being bright. HD668 B is, however, even brighter, and a bit more aggressive.

If you'd like a bit more lowend, you can try adding more layers of foam in front of the drivers.

If you one day find yourself with 30$ you don't know what to do with, I'd recommend you try out the 668 B's - If my description of the sound seems like something you'd like.

I am not going to go more in-depth about the sound, as I do not consider myself to be experienced enough to properly describe other sound characteristics - and I do not want people to be mislead by improper descriptions

First, off the Superlux HD-668 B are a great value for what you get. I recommend modding them for better listening sound and comfort.

Mods:

• Added electrical table inside the cups covering the holes. This lowers the sound stage but not too much and helps control the sound.
  
• Removed paper inserts in the cups because not needed with 1st mod
  
• Removed foam inserts. Clears up the sound, helps to tame the treble, and also, bringing the mids forward.
  
• Replaced stock earpads with Tranesca leather Angled big overear earpads. This gives comfort over the cheap stock pads
  
• Resoldered the poorly done wires for better lasting connection.

Fixed the clamping by stretching the headphones out.

Testing:
Equipment Used: SMSL sApII headphone amp running through an SMSL M2 USB DAC using Digital Output mode in Ubuntu MATE 18.04 (Linux) with PulseAudio.
Method: I listen to a wide variety of genres from Jazz, Rock, Metal, Electronic, and Classical/Orchestra. So I tested a bunch of songs from each different genre and they all sounded great without anything missing from them.

Sound:

• Treble is way too hot and have a harsh sound. To fix this is to trim back the 4khz - 10khz rage in an equalizer but I have fixed this by modding these cans.
• Mids are not pronounced and are covered up by the harsh sounding Treble. This can be fixed with an equalizer or mods.
• Bass is punchy and not overpowering that it will blast your head off.
• Lows are not missing anything in their range. They sound accurate and are very responsive.
  
• Vocals are very clear and natural.

Bulid Quality

Superlux HD-668 B is not the best bulid quality but at this price point I wouldn't expect it too be. Its made of plastic but nothing is wrong with that. The stock earpads are cheap and uncomfortable. I recommend replacing them with a good quality pair of earpads. Also, the wirering inside is poorly done. The head pads are not bad and can be adjusted. They are lightweight so they can to be worn for long periods of time.
​

Intro (important)
Before you continue reading, you can and should read my ‘about author’ page on head-fi to get a taste of my sound preference and test tracks. I bought these for $42 AUD ($30 USD) on sale at Gearbest. I bought these after reading all the raving reviews, even some comparing it to the Sennheiser hd600 but I guess they were all hype.

Listening and tests were mainly done with my Xiaomi 4X phone using Spotify's extreme quality (320Kbps, 24bit, 48Khz?). Note, my Xiaomi 4x output is slightly warm sounding and bassy (a solid 3-5dB more bass) compared to audio from my Ipod 5th gen and my computer (I5 core). The 4X output also sounds noticeably clearer and has better imaging than both my ipod and computer.
I usually listen at a low to very low volume. When using my Xiaomi 4X I listen at 20% of max volume (3 notches). Thus why I prefer a slight L or V shaped sound signature as bass output decreases with lower volumes. This also means my evaluation of the bass might not be as accurate.



Sound

I have listened to these headphones for roughly 24 hours accumulated over a month. I initially burned them in for half a day. The headphone still sounds the same, maybe just a very slight decrease in treble. Volume is quite soft, I need to turn my Xiaomi 4X volume up to around 30-40% to be as loud as my Sony MDR-ZX600 at 20%.



- Treble is way to Hot, particularly the highs. This could be attributed to the multiple relatively large peaks which are present at around 2k, 6k, 10k, and 15k (thanks to Rtings.com frequency chart). The biggest peaks are present at 10k and 15k. As a result the headphone sounds very unnatural and harsh. I would not consider myself a treble sensitive person but the super boosted highs just make it sound so unnatural. Like Tyll from Innerfidelity said, I have to admit these do sound pretty decent IF you EQ everything from around 1.5kHz gradually down to 5dB or even more.

I see some people being shot down (even comments being hidden What?!!) for saying the highs are too hot as though there’s some kind of cult following thanks to the headphones hype. Believe the hype if you want but just take a moment to think about it. Tyll from Innerfidelity is at his retirement age meaning his ability to hear highs is hampered, yet he says the highs are way to hot, like “razor blades”. Doesn’t that ring any bells? Maybe at very high volumes the bass might come out more thus balancing out the treble but even then I did not find the bass to be strong enough to mask the treble. Regardless, you shouldn’t be listening at high volumes, unless you enjoy accelerating your hearing loss.

Anyways, below is my EQ setting. Even with my EQ setting treble may still be hot for some. I’ve also attached a picture of a frequency curve versus age graph for those who do not know about age-related hearing loss (Presbycusis).






Otherwise like I said, these will sound very unnatural and extremely harsh. Although mids are already quite forward, I experimented with removing the foam screen in front of the driver to further boost the mids. Mids did become even more forward but it also lifted the already super elevated highs. I have even swapped the stock pads with Velour pads which only reduced the isolation. Thus the bass was reduced which brought forth the hot highs even more.


- Mids are a bit forward but nowhere near as much as the highs. I find it okay, some may say it is a bit recessed which could be attributed to the relatively more prominent sub-bass and super elevated highs.Personally i did prefer a little more of the mids hence why i experimented with taking out the dampening foam positioned in front of the driver.


- Bass is okay or a little bad with stock pads and very bad with Velour pads. With stock pads (plastic pads) I have to say bass gave more than what I first expected given that it is a semi-open back design. Sub bass is quite decent, nearing the amount that my Sony MDR-ZX600 puts out though doesn’t go as deep. Mid-bass is tight and has good quality but is a bit soft especially when compared to the mdr-zx600. Overall, I’d say bass is quite coherent and neutral besides the elevated sub-bass.

With Velour pads, bass was pretty much non-existent as the velour pad could not create a seal since it is made of fabric. As I said before, this brought forth the mids and already elevated highs even more.



Soundstage and imaging

I hear quite a few people say that these have a very wide sound stage but I do not think so. There is a difference between having a big soundstage and sounding diffused. I don’t know if it’s because the bad implementation of the semi-open design and/or the bad tuning but the 668 sounds quite diffused like listening to a concert from 100+ metres away. Good soundstage should sound like being surrounded by musicians a few metres away. If you want to know what very good soundstage and imaging is like then try the Sony mdr1A, you will tell from comparing that the 668B is diffused. Imaging on the 668B is pretty much on par with my mdr-zx600 if not a little worse due to the diffused soundstage.

Isolation

Pretty much non-existent due to the semi-open back design.

Design and comfort

It is mainly made of cheap feeling plastic with visible joint gaps. The headband consists of a rigid metal wire structure and has two probes with pads that rest against the top of your head. The plastic pads made me sweat quite a bit and was uncomfortable since the two small head pads could not distribute the weight of the headphone sufficiently. As expected from a semi-open headphone, there are holes at the back of the housing which act as vents. The worst thing about the 668B was the stock pads which I just could not describe as pleather but rather as plastic. The plastic pad was very rigid and made my ears sweat quite a lot. It was so uncomfortable that I had to make a permanent switch to velour pads even though that meant near non-existent bass. Apart from all the negatives, I must commend Superlux for implementing detachable cables on such a cheap headphone and providing a 3m cable.
Below is a picture of the headphone with velour pads on.





Summary

The 668B is just not worth it. You could have better headphones for roughly the same amount of money (such as the Sony mdr-zx600) or even better to invest in a slightly more expensive headphones under $100, that way you don’t need to think about upgrading for a while. There is no excuse for EQ, any headphone put through a good EQ software can sound decent. It’s like strapping a jet engine on a Toyota Prius, of course it would out speed a Ferrari, but will it perform and drive as coherently? No. Plus I do not want to waste time switching my EQ pre-set every time I want to listen to the 668.

I could only recommend the 668B to the elderly or anyone else who has hearing loss. Or for anyone who is on an extremely tight budget, want a neutral sound, does not mind spending time switching EQ pre-sets, and are willing to spend extra on better ear pads. Even then you’d still have its diffused soundstage and near non-existent isolation.

I’m way late to this party but you know what? I’m glad I came. Have you been looking for a super affordable headphone but are overwhelmed by all the choices out there? Let me simplify it for you; The Superlux HD668B is exactly what you’ve been looking for.

Superlux was started in an apartment building in Taiwan over 30 years ago. They have continued to grow and now have a huge facility in the industrial zone at Lan-Yuan port, China, where they make headphones, speakers, microphones and a bunch of other electronic gear.

At the time of writing, the Superlux HD668B is listed at $34.99 and is available at Gearbest here.

This product was provided for the purpose of an honest review. I’m not affiliated with the company and all observations and opinions here are my own.

Pros

• Punchy, articulate bass
• Clear and detailed sound
• 2 cable extensions included
• Price!

Cons

• Stock earpads are a bit thin

SPECIFICATIONS

• Drive Type: Semi Open Back
• Frequency Response: 10-30kHrz
• Sensitivity: 98 dB SPL/1mW
• Maximum Power Input 300mW
• Impedance: 56 Ohm
• Weight 7.8oz (222 grams)
• Cable: Removable 1M & 3M
• Plug Adapter: 3.5mm to 6.5mm (1/4 inch)

Package and Accessories
The Superlux HD668B comes in a large but simple box with an image of the headphones and model number on the front. On the back and sides are some features and details of the included accessories.

When you open the box you see the provided cloth carrying/storage bag. The headphones are secured in a cardboard cutout which holds them in place. It’s a simple presentation but it’s practical and the basic materials used help to keep the cost down.

Included in the box are:

• 1x Superlux HD668B headphones
• 3.5mm to 6.35mm adapter
• 1x 3 metre female to male 3.5mm cable
• 1x 1 metre female to male 3.5mm cable
• Carry bag
• Cable clip
• Instruction manual

That’s not too shabby considering the price you’re paying. Having the two cables provided is really something I wasn’t expecting but it’s very appreciated and also a very practical addition. At this point, just seeing my first glimpse of the headphones and the two cables, I was already thinking what great value this is.



Build Quality and Design
To be honest, I wasn’t expecting much in terms of build quality. I mean, heck, I consider $35 cheap for earphones but for a full-sized over-ear headphone? C’mon! As I lifted the headphones out of the box my anticipation grew.

Why, you ask? The answer is simple; Because they feel pretty good! They’re very light but not at all loose or flimsy. Everything feels pretty robust a solid.

At the heart of the build are the spring steel wires that form the headband. They run from the top of the headphones all the way down to where the earcups are attached. Partway down the wires is a plastic joint on each side which adds some rigidity and also holds an additional pair of wires that are attached to the self-adjusting “wings” that sit on the top of your head.

The earcups are large and made from a light but robust plastic. There is a series of concentric circular holes, covered with a metal grill, place around the centre of the earcups. These give the headphones their semi-open back characteristic.

The inner part of the earcups pivots slightly in and out, while the spring steel wires twist back and forth, so the headphones naturally find the right position on your ears.

Looking at the earpads, they’re quite large and easily fit right around my big ears. The pads are made from a PU leather with a foam interior. There’s also a sheet of foam covering the drivers so there’s some padding between your ears and the driver covers.

These pads are easily removable, so you can replace them if they get worn or you can get some third-party alternatives for added comfort.



Comfort and Noise Isolation
I find the Superlux HD668B extremely comfortable to wear. The clamping force is sufficient to hold the headphones securely on your head and you can move about easily without fear of them falling off.

Thanks to the large diameter of the earpads, any pressure is spread over a large surface area so they don’t cause any discomfort at all. The only thing that might be an issue is the earpads becoming quite warm, due to the firm pleather covers. I imagine if I were to upgrade to some third-party replacement pads, the HD668B would be every bit as comfortable as my Beyerdynamic DT990 Pro.

Being a semi-open back, the HD668B does not have much passive noise isolation. I can still easily hear the clacking of my mechanical keyboard as I type this, as well as the television in the background. This is normal for this type of headphone and if you’ve had open or semi-open back headphones in the past you’ll know exactly what to expect.



Cables
Finally, there is the external cable connector that differs from the usual female jack type on most headphones. The HD668B has an external 3.5mm plug, onto which you connect a female 3.5mm cable extension.

Both the 1-metre and 3-metre extensions terminate in a straight 3.5mm plug which is perfect for connecting to a mobile phone, portable DAP or computer. There’s also the included 6.35mm adapter if required to plug into a desktop amplifier.

As for the cables, they have a smooth, black rubberized sheath. They’re fairly supple and don’t have any kinks or unruly bounciness. Another bonus with the cables is that there is almost no microphonics at all, even when walking around. In fact, holding the cables in your hand you might wonder again – how can they provide all this for so little cost?



Sound
Any scepticism I had vanished as soon as I heard the first notes coming from the HD668’s transducers. These things sound ridiculously good (in the context of their price). I was greeted with a mildly V-shaped signature with a touch of warmth, along with clarity and detail.

The tonality is superb, the balance is just right – not analytically boring, nor overly fun coloured. There’s a healthy dose of bass impact, clear and intelligible midrange (albeit a touch recessed) and airy, crisp treble.

GEAR USED FOR TESTING

• ATC HDA-DP20
• Acoustic Research AR-M20
• PC/MusicBee > Topping DX7
• Samsung Galaxy Note 5

BASS
This is one of the most surprising aspects of the HD668B. The bass is well articulated, textured and doesn’t show any sign of bloat or woolliness. Mid-bass has nice impact with a fairly fast but natural decay. There’s no noticeable bleed into the midrange. I love the quantity of the bass in relation to the mids and highs. Clearly, the person who added the B (for balanced) to the model number knew what he was talking about.

Sub-bass also has a satisfying goodness. There’s a nice weight to it and a fast, controlled rumble which, similar to the mid-bass, does not intrude over the midrange. The HD668B revels in its control here, bringing the party without the associated hangover.

MIDS
The midrange has great tonality throughout. Lower mids are a hint lean but still have enough body so as not to sound hollow or too distant. The upper midrange is a little more upfront and can be a little edgy on occasion but having said that, it’s an area my ears are particularly sensitive to.

Vocals sound natural and come through with clear intelligibility. The HD668B renders voices with just enough warmth that they sound organic but maintain clarity and texture.

TREBLE
The treble is light and airy with a hint of sparkle. Detail retrieval is very good and for the most part, the treble is non-fatiguing. On brighter tracks, some sharpness can be detected but that’s mainly due to the HD668B’s transparency; it doesn’t try to smooth over the treble but rather aims to faithfully reproduce the recording.

SOUNDSTAGE
The Superlux HD668B presents a soundstage with above average width and plenty of height, accentuated by its airy characteristic. While the depth is fairly ordinary, instrument separation is still good and maintains some space between various elements.

Comparisons
BEYERDYNAMIC DT990 PRO – 250 OHMS ($160)
The DT990 Pro is more heavily V-shaped, with more accentuation in the treble. The Superlux HD668B has just a little more weight in the mid and sub-bass areas. Both share a similar width in the soundstage but the DT990 Pro has more depth and roundness to its stage.

Vocals are a touch more recessed on the DT990 Pro, however, it does have a slight edge in tonal accuracy. The DT990’s vocals are a little richer and vibrant, where the HD668B is somewhat dry. It’s really amazing how similar these headphones sound, the biggest differentiator is the treble. On the DT990 Pro, the treble has more sparkle but it’s also more strident and fatiguing.

In terms of comfort, the DT990 Pro is superior. It has slightly less clamping force and of course, has those lovely velour earpads that are thicker and softer. I’m fairly certain though, that if I were to put the Beyerdynamic pads on the Superlux, the comfort level would be near identical.

MSUR N650 ($90 – $100)
A bit of a hidden gem, the MSUR N650 has a warm and inviting sound. It’s got more mid and sub-bass than the HD668B but doesn’t have the same masterful control. Bass on the N650 carries more weight and has greater impact, giving the overall signature warmer overtones.

The N650’s midrange has denser notes, making vocals more intimate and closer to the listener, even though the N650’s midrange is more recessed.

The N650 shares a similar treble to the HD668B, which is crisp and airy. Its soundstage is not as wide but it does have more depth and superior imaging.

Comfort-wise, the N650 has softer earpads but they sit more on the ears rather than around the ears like on the HD668B. Both headphones are initially comfortable but I find my ears need a rest with either one after 1 – 2 hours.



Superlux HD668B Conclusion
The Superlux HD668B is simply brilliant for such a low-priced headphone. Even today, it still holds its own against products costing double or triple the price. The balanced, airy and transparent sound will surely surprise you and likely exceed your expectations.

In light of all this, I’m stumped as to why there are so many 4 star reviews for this headphone. Sure, that might be accurate if you were looking at it purely based on sound quality alone. But when the cost is taken into consideration it’s a no-brainer. Add to that the comfort, build quality and the fact that you get 2 cables as well, the HD668B is easily worth full points, IMO.

So, if you’ve been looking for a really inexpensive headphone to start your audiophile journey, look no further. Get yourself some of these today.

*This review was originally posted on my blog. You can see my other reviews over at Prime Audio.

It's hard to review products that are at either end of the pricing spectrum. It's hard not to be critical of products who's high price makes you expect the best. By the same token, it's human nature to root for the underdog.

So please take it with a huge grain of salt when I say: "These are the best monitoring headphones ever".

First, see above. The low price makes it hard to find fault with something that costs so little and yet delivers so much.

Second, if you like bass, you won't like these. It's all about a clean and even clinical sound. Sound that makes you dissect music instead of listening to it. The B in the name of the HD 668B's stands for balanced, but they are not balanced at all. There is a clear preference for highs that gives the headphones a "live" sound in audiophile lingo. Most audio engineers I know would probably call this kind of balance: "good for analytical monitoring".

Any small mistake will be exaggerated and you will wince at any off note. Sound compression comes through loud and clear as well, and your favorite mp3 will sound broken.

Switch to a better sound source (high bit-rate or lossless files) and this particular problem goes away instantly. Instead, you will be surprised to find that despite their elevated highs they are not overly sibilant.

Apart from being cold in their presentation they do have one more definitive trait to the sound: Open. The box proudly proclaims a "Semi-Open" design, but don't believe that for one second. There is no stopping air from getting in or out of these particular cans. However, that does give them a wide sound-stage, and one that I have never heard at this price-point.

You don't get enveloping sound with them. Imagine sound laid out inside an infinity symbol rather then a circle. Any sounds that are far in front sound like they are either above you or in your brain though things that are slightly off to the sides are well positioned.

Before starting the review, I had plans to compare them to AKG 240's, ATH M50x's and other such studio or DJ headphones. They don't compare. The sound is wide, it's open, it's clear, but they lack refinement both in the low end and the boosted treble.

This raw sound will not make all music sound heavenly through them, but listening to live and especially orchestral performances from a good source makes you feel like you're in the pit with the rest of the orchestra.

Bottom line, if you want to listen for errors in music, these will help you find them. If that doesn't sound appealing to you, I'm not surprised. I do think that's what they're made for though, and they do a damned good job of it.

NOTES:
1) Testing was done on both laptop/desktop/portable devices and an Onkyo T8020. Sound sources were mp3, flac, vinyl.
2) About 50 hours of active burn-in were done, and the low end did loosen up a bit in this time, so they do benefit from it.
3) They are almost identical to the Superlux HD 668B and on a blind test you cannot tell the difference between the two reliably.

Available for right around $40, the Superlux HD668B is hands down my favorite entry level open back headphone. As some one who started out with a Beyerdynamic DT 990, my cost of entry to the world of audiophile headphones ran me right around $250. That was for both my headphone and the little amplifier I needed to power it properly. What makes the Superlux HD668B so amazing, is that it offers a similar sound as the DT 990, clean, clear and wonderfully detailed without sacrificing bass, for significantly less money AND without the need for an amplifier! 
 

​

You can purchase here on Amazon for $39.95
 
 
 
Specifications

 

Drive Type: Semi Open Back
​

Frequency Response: 10-30kHrz
​

Sensitivity: 98 dB SPL/1mW
​

Maxium Power Input 300mW
​

Impedance:  56 Ohm
​

Weight 7.8oz (222 grams)
​

Cable: Removable 1M & 3M 
​

Plug Adapter: 3.5mm to 6.5mm (1/4 inch)
​

 ​

 
 
 

 

The Superlux HD 668B comes in very simple packaging. Cardboard box, with the brand and product name on the front. Specifications are listed on the back side, and the left panel has depicts what is included inside.
​

 
​

 
​

 
​

 
​

 
 
​

Accessories include a 1M and 3M female to male 3.5mm TRS along with soft plastic cloth carrying bag. Given the cost, I'm very happy to have the addition of the adapter and two cable lengths! 
​

 
​

 

 
​

 
​

 
 
 
The design is simple, reminiscent of AKG, and more importantly it fits almost every one. I've never personally had an issue with the wing system, though I've owned a few Audio Technica Headphones myself so I'm used to it.
 

​

 
​

A detachable cable, and easier to power driver make it easy to pair the Superlux HD 668B with a variety of sources. I've enjoyed it with my LG V20, my Audio GD NFB10ES2 and even my New Nintendo 3DS. With each, the quality of sound and total volume was beyond sufficient. For music play back I've primarily used my HM 601, and I will be using that as my primary source for the sound portion of this review.
 
I also purchased a KetDirect 4.5ft BlueCloth cable terminated to a right angle 3.5mm, I happen to prefer a right angle 3.5mm for my needs and if you need something different you're free to upgrade and swap cables how ever you see fit!
 

​

 
 

 
With a $40 cost, I'm satisfied with the build quality of the HD 668B, the plastic is sturdy with some flexibility to it.
 
 
 
 
 
 

 
The wing system bends and allows the cups to place themselves just over the ear, and the ear cups also flex and rotate to further help with the fit.
 
 
 
 
 
 

 
 
My only qualm with the HD 668B is quality control, sadly my first pair had a very loud resonance on the left driver from around 230-250hrz. I simply returned that one and repurchased another pair from amazon. Thus far I haven't had any problems with the replacement.
 
 
 
 
 
 
 
 
​

 
 
On the plus side, the pads are also removable and easy to swap out! I've yet to change mine out, but doing so does offer changes to the overall sound, so for this review I'm using the stock pads.
 

​

 
​

I find the stock pads to be plenty comfortable, even in the heat and humidity that's common here in the south eastern United States. Being semi open, the headphones do block out some central to higher frequency noise, things like fans and traffic. However you can still hear people speaking, vehicles and the rumble of heavy to light machinery. I've walked around my house while cleaning, or working with no issues. I've also spent some time at the gym with them, and while the sweat from the pads was problematic, the lack of noise was not. I was able to focus on my music, while still having enough audible awareness of those around me.
 
 

​

 ​

Sound​

For the purpose of this review, I paired the HD 668B with my Hifiman HM 601.​

 
​

The overall tone of the Superlux HD668B is Cold and Dry, I find it's presentation to be very Bright and the overall sound signature is a fun neutral. Measurements show that it has a slight v shape to it's frequency response.
 
I really love the bass of the HD 668B because it gives a wonderful speed and texture to a variety of drums. It even stays true to the power of an electric bass and the warmth of a stand up bass. My favorite moment with them, was finally getting to really HEAR the bass line in Metallica's The Shortest Straw, in addition to some intimate fret action added into one of my favorite bass solo's. Synth Sub bass lines are the only draw back to the HD668B bass presentation in my opinion. I enjoy the extra speed and hardness that the HD668B has to it's bass response.
 
The mids are very dry, however out of my HM 601 I found a wonderful timbre to many brass wood winds. Trumpets, the sax and even flutes all had a very life like presentation, trumpets maintained a metallic edge without sounding tinny. The Alto and Tenure Sax both had excellent body and bite. The bright presentation of the HD668B also presented the quick breath taken in-between each note. It is problematic with stringed instruments. Heavy Metal riffs had a nice crunch, but not real bite to them. Acoustic guitars, while having great timbre in the lower notes, had a very uneven sound overall and the same can be said for almost all stringed instruments. The harmonics of many of those instruments were lost in the overall presentation of the HD 668B.
 
Top end clarity is another pleasurable quality of the HD 668B, high hats, cymbals and the brightest guitar solos all have a wonderful sense of clarity and air. While some may find the treble to be too hot, or too bright, I really do like the shimmer that the HD668B brings, really makes you feel like you're walking on air.
 
Sound stage presentation is very wide, but lacks some depth. Left, right and center separation are excellent and though it lacks depth, the Superlux HD 668B holds you more or less equidistant from each instrument. On tracks with a very strong sense of depth it is audible, but it is by no means top of the line.
 
It's lack of depth is often overshadowed by it's amazing mirco detail or transparency, it's a headphone that will certainly add a sense of atmosphere and ambiance to your music. An let you really hear EVERYTHING.  With the Superlux HD668B the devil, is certainly in the details! Good or bad, the Superlux HD 668B brings detail, if it's captured, chances are you'll hear it. This is also true of the equipment that you pair the HD 668B to, my HM 601s warmth helped to improve the tone of the HD668B, it softened a very stiff bass, and helped balance out the low to central mids.
 
In conclusion, the HD 668B is an incredibly transparent and fast headphone. While it's a tad drier than neutral, it pairs very well with a lot of entry level source and amplifiers, so chances are you'll probably not notice a lot of what I have,  and best of all it's $40!!! So not only is it a total steal for this level of transparency, but it's also a fun headphone to own! There are so many ways that you make little adjustments to how the HD 668B sounds, from the cable you use, to the pads, to your source, to your amp, and if you own tubes I'd imagine it would be a blast to listen to tubes with! All in all, I highly recommend the Superlux HD 668B.
 

Comparative Music/Cinema Break Down ​

Click here for a look at my review process ​

 ​

The Zephyrtine - A Ballet Story [ Fundacao Orquestra Estudio, Rui Massena]  #09 Dance of the Zephyrtine 

• Superlux HD 668B ​

  1. I really loved the width of the sound stage, but the lack of depth got to me.Often times I found I couldn't appreciate the soundscape as a whole it constantly felt like something was missing. With my HM 601 as a source, I really loved the tone of the trumpets, they had a nice edge to them. I found the flutes to have a good shimmer to them, along with excellent clarity and decay from the bells. The high hats and snares sounded excellent as well, with a good crisp sound. Though the big timpani drums sounded very boomy with no real deep bass body to them, the rolled off sub bass response was pretty obvious with this track. 
• Switching to the Nhoord Red V1

  1. The Timpani drums don't sound as boomy, or forward, and there's a nice low end rumble and natural body to them. I do miss some of the shimmer in the high end with the Nhoord though, it's a tad mellower than the Superlux HD668B. But the more balanced mids on the Nhoord Red V1 add a playful quality to the flutes, that was missing with the Superlux HD668B.
• Switching to the HE 4

  1. Finally some DEPTH, while both the Nhoord and Superlux both had good width, the HE 4 brings a more holographic or 3D sound scape. In addition, that extra space presents mirco detail a lot more naturally. It's not as IN YOUR FACE, as with the Superlux HD 668B, not to mention there are a few details that the HE 4 brings to light, that neither the HD 668B nor Nhoord picked up. 

Kind of Blue (2015 Mobile Sound Fidelity Labs Re-release) [Miles Davis] #01 So What

• ​Superlux HD 668B ​
  1. The double bass has a really cool, smokey mellow tone. Though, it sounds a little uneven, the lower notes overshadowed by their harmonics, and the upper mid bass notes are just too... forward. But nitpicking aside, the bass line is very chill, very laid back and enjoyable. Still, the horns really steal the show, of all the wood winds, the HD 668B LOVES horns, the tone is perfect. Good warmth and body alongside with a nice bite. The high hats are amazing to listen to as well, they really feel like your walking on air, good shimmer and great extension.
•  Switching to the Nhoord Red V1
  1. That double bass line is a lot punchier on the Nhoord Red V1, it's not as mellow, though there is a much more balanced bass response. Still though, the horns aren't quite as bitey with the Nhoord either, it gives them a really beautiful sweetness! Overall, the Nhoord brings a more balanced response, which works nicely in this jazz piece! As I notice the paino more with the Nhoord than I did with the Superlux HD 668B.
• Switching to the HE 4
  1. ​​The HE 4 brings the best of both, the bass has just the right mix of punch and decay, the tone isn't uneven nor any part of it over emphasized. The HE 4 also brings a different sense of bite, lower softer notes are sweet, the more aggressive notes have bite to them! Where as the Nhoord gave everything the instrument played a sweetness, and the HD 668B made it all kinda of bitey, the HE 4 brings each quality more naturally. A sweet soft tone, then instantly a shift to a brighter bitey note, then back to a smoooth sweet tone. Gives you a very real sense of almost being right there with the band! An the high hats, are equally nice on all three. 

 
Igor Levit: Bach, Beethoven, Rzewski #01 Goldberg Variations, BWV 988 - Aria with 30 Variations 

• Superlux HD 668B ​
  1. SHOUTY, is really the only description I can give about the HD 668B with regards to this track. Being a piano solo, the uneven nature of the mids is PAINFULLY obvious. The upper mids are excruciatingly SHOUTY, in comparison to the over emphasis mid bass and recessed low to central mids. While I really do like the HD 668B with classical, it does not do well with... a singular piano... at all... it is just a cacophonous mess. That said how ever, amidst this mess there is some nice mirco detail! This song has the weird sound of... something moving around in the background. Almost sounds like some one dancing in a ball room as the music is being played... and that detail is present... even amidst the SCREAMING upper mids...
• Switching to the Nhoord Red V1
  1. Even the Nhoord Red V1, is still too warm in this track for my tastes. It's... forward mid bass is still annoying me. The mids are much more balanced with the Nhoord, and there's a real sense of beauty to each strike... but this beauty is short lived by a some what forward bass. Which can over shadow the beautifully delicate and short lived strikes, that our pianist makes such simply gorgeous use of, though... the  Nhoord Red V1 does not maintain the oddly distinct little bit of detail, that is our dancing background noise
• Switching to the HE 4
  1. ​​The tone is VERY proper, delicate when needed, you can hear the weight of each stroke, the heft of the deeper notes does not over shadow the beauty and delicate tactility of the quicker strikes, and amidst this astonishingly beautiful song is the gentle sound of a dancer moving around in the background. Where as the HD 668B can be a bit forceful with it's mirco detail, the HE 4 is much more polite and spacious with these details. Thus adding a very surreal sense of ambiance. 

 
Collected [Shadow Child] #07 The Verdict (Part 2) (Edit)

• Superlux HD 668B
  1. Fun, this track is just a lot of fun with the HD 668B. The slight v shaped frequency response really does add something FUN to this deep house track. While rolled off, the sub bass does still manage to add a little bit of texture. Still, the dominant upper mid bass does really steal the show. Great decay, nice sense of weight and slam. The overly dry bass of the HD 668B is a compliant for this track! My only gripe is the vocals are a bit thin and un-natural, other wise the synth horns and percussion all layer in nicely.

•   Switching to the Nhoord Red V1
  1. ​​Sadly, the Nhoord is much more balanced, so while there's a more satisfying deep bass kick, the overall lack of bass in comparison to the HD 668B is kinda boring. Though, the vocals have a really beautiful naturalness to them, and the bass has a touch more texture but... and more atmosphere... but all of these extra qualities are the result of a... kinda boring bass line. When the bass is suddenly not THROWN IN YOUR FACE, you have time to appreciate the extra details. Like the beautiful decay of a metallic chime, or how the high synth horn echos on the left and right channels... those extra details are really cool... but not an equal exchange for a less fun bass line.
• Switching to the HE 4
  1. ​​Best of both worlds, for an open back the HE 4 has a VERY AGGRESSIVE, HEAVY weighty bass slam. With very little added decay. Not to mention it's almost linear from 20- 200 hrz, so the texture is almost un real, feels like a big heavy monster breathing on your neck at times, and all of this massive slam and weight along side the really cool details that I first noticed in the Nhoord. My ONLY problem with the HE 4 and EDM is that truth be told, it is a bright headphone, and this brightness is really only noticeable when your listening to any synthesized or digital sounds. So by the time, I've got the volume to right around 87-88 db's SPL the highs do get a little hot 

 
... And Justice for All - [Metallica] #05 The Shortest Straw

• Superlux HD 668B 
  1. The long last bass line makes it's return! The very in your face mirco detail in the HD 668B works wonders for the very buried bass line in this classic Metallica song. While I loooove getting to hear that, there's a real lack of bite. The guitar riffs have a nice crunch, the double drum has excellent attack, but the song as a whole lacks bite. An while turning up the volume does "technically" help, you still left with an over zealous top end... and not enough bite.
• Switching to the Nhoord Red V1
  1. ​​The Nhoord Red V1, brings back the bite! The vocals have a nicer more tactile edge to them, and the drums have a better defined space within the sound stage. Though... while the sound stage is better defined it's not quite as big as on the HD 668B, the Nhoord trades width for definition and intimacy. The bass line is still audible, but it's a bit over shadowed by a nice heavy bite on the guitars! 
• Switching to the HE 4
  1. ​​Best of both Worlds again, there's all the bite you could, want alongside a crazy amount of impact in the double bass drums. All without overshadowing that bass line or sounding too "intimate" 

Following the HD600s, I had simply obtained the Superlux 668b as a point of comparison and reference, as it is a well know and popular budget Headphone. My brother also uses a pair that he swears by (unless he is borrowing my SHP9500). The simple truth is that the Superlux 668b cuts through detail like a knife. Rough and tumble sound, like a cowboy; he gets the job done well with only 6 bullets, or 50 bucks, then tips his hat while he walks off into the sunset. Superlux went full high-noon and checked off all the boxes for a compelling sound without robbing the evening coach. The Superlux 668b follows suit of the KSC75 in being an incredible value in sound quality. Better still, the Superlux has some very well though out design features.
 
The tiny little 3.5mm cable (i dont know what else to call it) that is used to attach various lengths of auxiliary extension cable is fantastic.
As I am sure a few of you thought to do....

 
or better still.....
 

 
To be honest, this could perhaps be used with a bluetooth adapter (though you would look goofy to say the least.)
 
The sound signature strikes me as V- shaped with treble emphasis. I find this quite nice as a contrast to my Sennheisers and Philips. My warning label for this headphone is that they can be harsh. They can be very harsh. This also adds an extra sense of clarity at times. Going from the 668b to HD558s is like going to bight sun to a damp cave. 
I find the sound of the Superlux 668b good enough that I would consider mixing with them.
 
As I have found with pretty much every headphone (except IEMs) more clean power adds to the extension and balance. The Bass got some more growl from the Project Polaris as well.
 
The soundstage is there, but often times I felt as if they were trying to be a tad closed by shoving treble into my skull, while others they seemed almost distant. I have not pinned down exactly what causes this, but it is likely to do with signature. 
 
The fit is another point on which the Superlux 668b can go wither way. The stock pads are quite large and there is foam inside (not big enough for my dumbo ears though.) The wing things on top are meh at best, and honestly I would prefer a real headband, something like the AKG style that the Samson SR850 has. The good news is that the wire frame can simply be stretched or bent to whatever headshape you want. Tight or loose is all up to you. I only loosened mine a bit, but kept it tight enough that I could try to muster out some more bass.
 
The pads are fine. Honestly sub-par compared to many other headphones, but for the price they are fine. I got some velours for $8 on amazon. I do not like them as they were a little smaller than the stock pads in inner height, so I went back to the stock pads. I also noticed that the velours leaked more bass, but also seemed to add a little to the mids.
 
Song recommendation: Gunslinger – Avenged Sevenfold (fits the cowboy theme)
I quite like what these to with metal in particular.
 
Comparisons will be here:
 
Superlux 668b vs HD600:
 
The Superlux is much less forgiving and harsh, more treble, and gives excellent detail. The Superlux strikes me as a bit V shaped with emphasis on the treble comparatively. Strangely enough, I find the Superlux to be more forward, yet somehow less intimate. The 668b is definitely leaner than the HD600. Some people will likely find the HD600 to be relatively veiled in comparison. Some frequencies are a bit under-represented on the Superlux while the HD600 is more neutral. The real difference for me is that it sounds like you are monitoring a recording on the Superlux, While listening to music on the Senneheiser.
 
Superlux 668b vs HD700
 
Wile the Superlux can sound more inside your head at times; the HD700 is very 3 dimensional. The HD700 also carries more warmth and has more body. They both have similar treble spikes as well. I also get less splash from the HD700, as well as more resolve. I find the bass to roughly the same in texture, and tightness. The 700 again carries a level of warmth in the bass, which can make the 668b bass seem better to those who want raw visceral bass. The Superlux can be sibilant sometimes, while this rarely happens with the HD700. I also find the HD700 to be smoother (minus the treble spike) in typical Sennheiser fashion. Price/performance: Superlux wins by a landslide.
 
Superlux 668b vs Koss KSC75
 
These two sounded surprisingly similar. The Superlux is more detailed for sure, as the KSC75 gets more bass texture. The price increase over the Koss is clearly all going to the build. This shows as I am not afraid to be a little rough with the 668B. I also found the sound of the 668b to be more analytical than the KSC. In fact, I would even mix with the Superlux.
 
Superlux 668b vs SHP9500
 
Well. This is where the rubber meets the road. The SHP9500 is much more natural, smoother, and, to me, far more comfortable. The Superlux fights back by having more aggressiveness and is undoubtedly more crisp. The SHP9500 seems a relaxed compared to the 668b and The SHP9500 won in the intimacy battle.
 
Superlux 668b vs HD558
 
I found the Superlux to be far cleaner, and far less mid-bass heavy. The treble more rolled off with HD558. They are in many ways opposites. I think the Superlux is the more capable headphone, but I still find the HD558 to have that special something many headphones simply do not. The Superlux is a much better value for money, but it would not surprise me if more people prefer the HD558.
 
Conclusion: Like many, I have been in the tight budget category, and many see no reason to spend more on headphones. For those people, this should be a banner to fly. The price/performance is unquestioned in my mind. This is a genuine steal at the asking price. I will recommend the Superlux 668b without question.

---

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.

---

Intro.
 
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.
 
Conclusion.
 
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!

​

 

---

 
 
Preamble:

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.


Sound:

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.

Tonality:

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.

Resolution:

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.

Soundstage:

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.


Conclusion:


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.

Superlux HD668B Quick Review by mark2410

 

Thanks to GearBest for the sample.

 

Full review here http://www.head-fi.org/t/817561/superlux-hd668b-review-by-mark2410

 

Brief:  Stupid cheap sorta monitors

 

Price:  £20 or US$26

 

Specifications:  Headset type: Dynamic, Connectivity : Wired, Application: Computer, DJ, Mobile phone, Portable Media Player, Plug Type: 3.5mm,Full-sized, Driver unit: 50mm, Sound channel: Two-channel (stereo), Frequency response: 10Hz-30KHz

 

Accessories:  1 x 1m Cable, 1 x 3m Cable, 1 x 6.5mm Interface Connector, 1 x Cable Clamp, 1 x Storage Bag

 

Build Quality:  They feel sturdy enough in the hand but, well they aren’t the best looking nor the best to the touch.  They look and they feel kinda cheap.  I mean they seem sturdy enough but they are what they are.

 

Isolation:  Err, they are semi open so they isolate almost nothing.  These are not cans for using on the Tube or in a library.

 

Comfort/Fit:  Fit was easy and comfort was mostly good.  They do like to clamp pretty firmly and they did squish the bottom tips of my ears a little.  Still was fine to wear for few hours at a tmie with no probs.

 

Aesthetics:  Err, yeah see build quality.  These look very plasticky and not the sort of thing that says, oh hive got fancy headphones.  These don’t look awesome I’m afraid.  Functional they are over aesthetically pleasing.

 

Sound:  Where the previous aspects were a bit so so, the sound quality is jaw dropping good.  For the price, delivered for US$26 is just insane, I mean how, how do they even post them for that never mind that they don’t just sound decent but sound incredibly good.  It really is incredible.  These being the 3^rd Superlux I’ve played with I feel I can stop with the constantly checking they send me the right thing, that I’m looking at the right price.  These sound phenomenally good for the price.  The bass is so clean and articulate.  Death is so so but open cans always are really.  The mids are filled with detail and nuance.  A little dry, which enhances the perception of clarity and openness.  The treble is likewise the same.  So detailed and nuanced but it does like to get a tiny bit over eager and when you play back bad treble it will very happily assault you with it.  It takes no prisoners and that can be rather wearing, tiring on my little sensitive ears.  However the quality is crazy.  In terms of balance they are rather even with a slight bump to the uppers so the bass in particular with its open lack of depth can be over shadowed.  Bass head cans these are not.  Perhaps treble head ones maybe.

In short, wow, crazy good detail and clarity.  Bargain basement “monitor” neutral cans.

 

Value:  Stupidly stupendous good value.

 

Pro’s:  Insane good value.  Stunning audio quality.  Superb detail levels.

 

Con’s:  A little too eager in the treble.  Look cheap and plasticy.  Feel cheap and plasticy.