Superlux HD668B – Review

Superlux HD668B Headphone

Superlux HD668B

| Over-Ear | 50 mm Driver | Neodymium Magnet |

? Superlux HD668B, a super bang for the buck, semi-open headphone that built-up Superlux’s headphones reputation.

The Superlux HD668B features big 50 mm dynamic drivers, strong neodymium magnets, detachable 3.5 mm cables and a semi-open back design.

The cups of the Superlux HD668B are large and have pivoting/swiveling movements; the earpads are rounded like the cups and as large as them, fully capable of fitting any ears size inside.

The cables detach on the left cup and, contrary to most headphones with detachable cables, the connector of the headphone is a male 3.5 mm end instead of a female one. This male 3.5 mm cable section coming out of the earcup is very thick and rubberized (like the extension cables provided for free)

Superlux has the tendency to create wonderful products with phenomenal sound at a ridiculous low price and they also have the habit to design their products with a clear resemblance/inspiration to the aesthetics of iconic prime-branded headphones like the:

In the case of the Superlux HD668B (model being reviewed on this article), the brand says: “Both the HD668B and DT990 have a similar frequency curve. The HD668B delivers a natural and excellently balanced sound, presenting the crystal clarity and high resolution demanded by professional users.”. Superlux is suggesting the ultra-famous Beyerdynamic DT990 by nominating “DT990”; clearly they are not referring to an aesthetics resemblance with the Beyerdynamic Headphone as they far from having similar looks.

The design of the Superlux HD668B has a “fusion-inspiration” from the headband of Audio Technica Headphones (specifically some of their high-fidelity models like the Audio Technica ATH-R70X, Audio Technica ATH-W5000Audio Technica ATH-AD500XAudio Technica ATH-ADG1X) and the cups of AKG Headphones (like the AKG K240 and AKG K240 MKII)

The Superlux HD668B is compatible with Android and Apple devices.

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Superlux HD668B Review

Tests & Scores



Superlux HD668B weight in Ounces and Superlux HD668B weight in grams.

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Accessories & Packaging

The Superlux HD668B unboxing results in a soft carrying pouch, 1 meter cable extension, 3 meter cable extension, 3.5 mm to 6.3 mm adapter and a cable clip to secure the connection between the 3.5mm male end (on the headphones) and the 3.5 mm female connector of the cable extension. Contrary to the Superlux HD681, the Superlux HD668B comes with a large packaging that holds, sufficiently safe, everything inside.



Bass & Sub Bass

The 50mm dynamic drivers and neodymium magnets inside the cups of the Superlux HD668B provide a well-resolved lower range that gives fullness and body to their overall sound. Mid-bass adds a good amount of punch and fun to any track without getting all over the place or stepping on mids. Sub-bass might not be as deep as a bass-centered closed-back headphone but it is very good for an open-back headphone (to be more precise, a semi-open headphone)

Applying an EQ, their mid-bass gets a bit punchier but mostly their sub-bass gets deeper, still do not expect a sub-bass depth like an EQ’ed bassy closed-back headphone.

When running the Superlux HD668B through our basshead tests they managed 47% of a Fiio E12 Mont Blanc‘s power at high gain, bass boost turned on and with a custom basshead equalization. The results were a huge increment of sub-bass and added mid-bass too; when reaching their maximum amplification (only near the top) they were able to answer back with a mild basshead rumble but we wouldn’t rank them as a basshead headphone by any means.


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Superlux HD668B Headphone
Superlux HD668B Headphone


Mids & Vocals

The Superlux HD668B mids are cozy, inviting and warm sounding. Higher mids provide the right amount of crispness without falling into forward or harsh sound. Male vocals and lower mids are clear enough and pleasant – if you want ultra clear lower vocals that take the lead role you will have to boost them a bit.

With an EQ, male vocals and overall mids sound clearer and more energetic. Higher mids add crispness but never fall into harshness nor start to reveal uncomfortable peaks.




Highs & Treble

The Superlux HD668B highs are excellently achieved with bright sound and a good amount of detail resolved. Nonetheless, piercing peaks are not very common but sibilance does show up on sibilant-prone songs. Much like with the Superlux HD681, their highs sound quality is way above their price.

An EQ adds a big amount of brightness and additional detail but you might have to be careful to not overdo it or you will introduce piercing highs and empower their sibilance too.



Superlux HD668B Headphone
Superlux HD668B Headphone


Sound Leak

The sound leaking out of the Superlux HD668B is as strong as you would expect from a non-closed back headphone. People nearby will hear the music/sound coming out from them but if you know that this is how open-back headphones work you shouldn’t be surprised.

By being a semi-open headphone and not a fully open-back headphone their leaking level is slightly lower than, for example, the Grado SR80e Prestige Series Headphone.


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Sound Isolation

Another typical aspect of open-back designs is that their sound isolation is not very effective and as the Superlux HD668B are semi-open headphones, their isolation is not very strong in comparison to a closed-back headphone.




The Superlux HD668B have a lightweight construction due to the Audio-Technica inspired headband, nonetheless they are robustly constructed and offer a great level of comfort. The wing-headband easily self-adapts to any head’s size and the cushioning pads on each wing gives them a soft area of contact with the head. The large leatherette pads provide a fully over-ear fit that removes the pressure on the ears that an on-ear headphone would had added.

Moreover, the Superlux HD668B have 3.5 mm detachable cables which allows them to fit either the 1 meter or the 3 meters cable (both included for free) or you can buy any compatible cable with a length, design, feature of your liking an use them with the Superlux HD668B. If you want to get creative you could even buy a Bluetooth adapter and transform them into an unique Bluetooth headphone with an open-back.


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Response to Equalization

The Superlux HD668B responded excellently to all the EQs applied for each audio frequency range. Lower frequencies added a very noticeable amount of sub-bass depth; mids gained clarity of their lower vocals and crispness on the upper mids but never sounded harsh; highs became crazily bright and detailed.


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Size & Fit

Superlux HD668B size and Superlux HD668B fit.

Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B
Superlux HD668B

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Scores Scores

Superlux HD668B Scores

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Frequency Response (raw)

Superlux HD668B Frequency Response

Superlux HD668B - Frequency Response
Superlux HD668B – Frequency Response

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Superlux HD668B Technical Specifications


TypeDynamic Semi-open
Driver Unit50mm
Power Capacity300mW
Impedance56 ohms
Frequency Response10-30,000Hz
CordRound cord
Cord Length3m + 1m
PlugStereo mini plug
WeightApprox. 222g
Supplied Accessories3.5mm to 6.3mm adapter; soft carrying pouch; 1m cable extension; 3m cable extension

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Superlux HD668B FAQ

How many drivers does the Superlux HD668B have?

The Superlux HD668B is a single driver headphone. Which means that the Superlux HD668B has 1 driver per side.

What type of headphone is the Superlux HD668B?

The Superlux HD668B is an over-ear headphone.

The Superlux HD668B is an open, semi-open or closed back headphone?

The Superlux HD668B is a semi-open back headphone but it could also be considered an open-back headphone.

Does the Superlux HD668B have a microphone?

The Superlux HD668B is a professional studio monitoring headphone that does not have a microphone nor a remote.

What is the price of the Superlux HD668B?

You can check the most up-to-date price of the Superlux HD668B by following THIS LINK.

Where can I buy the Superlux HD668B?

You can buy the Superlux HD668B, HERE

Which Superlux HD668B colors are available?

The Superlux HD668B is available only in black color.

What cable do the Superlux HD668B have?

The Superlux HD668B have a single-sided, round cable.

What cable connection does the Superlux HD668B have?

The Superlux HD668B cable connection has a 3.5mm mini stereo plug.

Are there replacement cables for the Superlux HD668B ?

The Superlux HD668B cables can be replaced with any compatible 3.5 mm cable.

Are there upgrade cables for the Superlux HD668B ?

Yes, the Superlux HD668B uses detachable cables, therefore you can buy any kind of compatible upgrade cable with a 3.5 mm connection.

Does the Superlux HD668B have Bluetooth / The Superlux HD668B is a wireless headphone?

The Superlux HD668B does not have Bluetooth but you can buy Bluetooth transmitters to use them wireless.

Is the Superlux HD668B compatible with Apple devices?

The Superlux HD668B is fully compatible with Apple devices.

Is the Superlux HD668B compatible with Android devices?

The Superlux HD668B is fully compatible with Android devices.


Superlux HD668B Photos

We highly discourage anyone from trying to apply our testings to your own earphones, the risk of damaging or permanently breaking your iems is absolutely probable to happen. With our standardized equalization and amplification tests we push the limits of the earphones to the extreme. If anyway you decide to do so, we cannot be held responsible of the damage done to your equipment. Do it at your own risk.

Superlux HD668B