Field Test · Studio Gear Review
Superlux HD-668 B MKII
In-depth technical evaluation of Superlux’s HD-668 B MKII semi-open headphones
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Spec Sheet
- Dynamic
- Circumaural
- Semi-open back design
- Max. sound pressure level: 98 dB
- Impedance: 56 ohm
- Frequency response: 10 Hz – 30,000 Hz
- Max. power rating: 300 mW
- Artificial leather ear cushions
- Single-sided, detachable cable
- Weight: 260 g without cable
- Includes 1.5 m 3.5 mm stereo jack cable, adapter to 6.3 mm stereo jack and bag
Studio Log
| Available since | January 2026 |
|---|---|
| Item number | 627946 |
| Sales Unit | 1 piece(s) |
| Design | Over-Ear |
| System | Semi Open |
| Impedance | 56 Ohms |
| Frequency range | 10 Hz – 30000 Hz |
| Adaptor | Yes |
| Replaceable Cable | Yes |
| Colour | Black |
| Max. SPL | 98 dB |
| Type Of Connector | Jack, mini-jack |
| Weight | 260 g |
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QC Pass — Field Test
Customer Review Summary
[META]Analysing the Superlux HD-668 B MKII headphones: sound quality, build, comfort and features of this budget semi-open model tested.Introduction to the Superlux HD-668 B MKII
The Superlux HD-668 B MKII is an over-ear, semi-open headphone system launched in January 2026. Priced modestly at £29, it targets users seeking decent audio performance without breaking the bank. With a dynamic, circumaural design, these headphones claim improvements over their predecessors, especially in sound clarity and build quality.
Design and Build Quality
Constructed with a focus on lightweight comfort at 260 grams (excluding cable), the HD-668 B MKII uses artificial leather for the ear cushions. The semi-open back design allows some sound leakage and ambient noise, balancing isolation with a wider soundstage. The headband employs a push-adjustable locking mechanism, replacing older elastic or winged support styles, ensuring stability without the risk of loosening over time.
Superlux also opted for a detachable single-sided cable with a 3.5 mm stereo jack and an included 6.3 mm adapter. The cable connection incorporates a locking system to prevent accidental disconnection, and given the common jack standard, users may easily replace the cable if needed.
The plastic housing exhibits improved precision and quality over earlier versions, although no metal decorative elements are present. Included accessories consist of a 1.5 metre cable and a carrying bag, adding value for the price.
Technical Specifications
- Impedance: 56 Ohms, suitable for portable devices and many audio interfaces.
- Frequency response: 10 Hz to 30,000 Hz, covering a broad audible spectrum from deep bass to extended highs.
- Maximum sound pressure level (SPL): 98 dB, adequate for most listening environments.
- Maximum power rating: 300 mW, supporting a wide range of output levels.
- Weight: 260 g without cable, light for extended use.
Sound Quality Assessment
The HD-668 B MKII presents noticeable improvements in driver performance compared to earlier models. Distortion, especially in the mid and upper midrange, is reduced, resulting in a cleaner tonal balance. The bass response extends impressively deep, dropping only 3 dB at 20 Hz, which provides a fuller, more accurate low-end reproduction than its predecessor.
However, there remains a pronounced and fairly broad peak around 8 kHz. While this can highlight fine detail beneficial for certain studio work, casual listening may find it somewhat fatiguing. Adjusting the response in this region with a parametric equaliser, or applying a simple physical filter (such as a thin layer of tissue in front of the driver), can mitigate this.
Once corrected, the headphones deliver a clear, balanced and engaging sound signature. The highs remain articulate without becoming shrill after modification, the mids are clean and detailed, and the bass is taut and controlled without overwhelming other frequencies.
Comfort and Fit
The ear cushions, though made of artificial leather, are relatively thin and may press uncomfortably on larger ears. Users have the option to add foam inserts or seek aftermarket padding for better comfort and isolation. The headband’s push-adjust mechanism offers precise fit adjustment with minimal pressure points, making prolonged listening sessions comfortable.
Practical Usage and Value
The headphone’s semi-open nature makes it suitable for quiet environments where some ambient sound can be tolerated. It will not isolate fully but offers a spacious soundstage beneficial for mixing or detailed listening. The inclusion of the adapter and carrying bag adds to usability for users switching between portable and home audio equipment.
The connectivity with a detachable cable and strong locking jack ensures durability and easy replacement, a welcome feature usually reserved for more expensive models. Minimal mechanical noise is emitted from the cable, and only typical casing noise arises from handling.
Conclusion
For a price of £29, the Superlux HD-668 B MKII represents excellent value. It addresses many criticisms of its predecessors, showing refined audio performance and improved construction quality. Its semi-open design and broad frequency response suit both casual and semi-professional applications. While minor high-frequency adjustments might enhance enjoyment, the headphones’ fundamental sound clarity, comfort and sturdy build make them a compelling choice in the budget segment.
Overall, the HD-668 B MKII emerges as a viable alternative to more established brands around this price point.
