Image © SennheiserEnjoy your music on a completely new level. An intimate, relaxed sound signature combines with outstanding precision and exceptional comfort — and now, extended sub bass — for a deeply moving experience. The extremely precise yet non-fatiguing sound of the HD 660S2 delivers even more impact with extended sub bass. With an optimized surround, transducer airfl ow, and coil our engineers doubled the sound pressure at the lowest octaves.
The Sennheiser HD 660S2 is a wired, open-back over-ear headphone designed for critical listening at home, offering a warm and smooth sound signature with improved sub-bass over its predecessor. It requires a capable amplifier due to its high 300-ohm impedance, and its open design means it leaks sound, making it unsuitable for portable or noisy environments. While technically refined and comfortable, it delivers a relaxed rather than punchy presentation, appealing to purists who value neutrality over bass impact.
Paraphrased from published reviews & specs - not an original hands-on test. Our AI disclosure.
| Driver | 38 mm dynamic |
|---|---|
| Driver type | dynamic |
| Driver size | 38 mm |
| Drivers per side | 1 |
| Frequency response | 8 Hz - 41.5 kHz |
| Impedance | 300 Ω |
| Sensitivity | 100 dB/mW |
| Sensitivity (dB/Vrms) | 104 |
| Driver | 38 mm dynamic |
|---|---|
| Driver type | dynamic |
| Driver size | 38 mm |
| Drivers per side | 1 |
| Frequency response | 8 Hz - 41.5 kHz |
| Impedance | 300 Ω |
| Sensitivity | 100 dB/mW |
| Sensitivity (dB/Vrms) | 104 |
| Active noise cancelling | No |
|---|
| Weight | 260 g |
|---|---|
| Detachable cable | Yes |
| USB-C | No |
| Connector | 4.4 mm balanced |
| Balanced connection | Yes |
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4 source(s) feeding this product's score.
Video reviews we found, each condensed to its verdict. They do feed the HearWiki score, at a measured weight below what a published written review carries.
11:47The reviewer finds the HD 660S2 to be a well-built, comfortable headphone with a darker, warmer sound than the rest of the 6x0 line due to a recessed 3kHz region, which reduces intimacy but can improve spaciousness on some tracks. It's not a technical upgrade over the HD 650 or 6XX, and the bass is not significantly increased, making it a side-grade that suits specific tastes rather than a universal recommendation.
11:04The reviewer finds the HD 660S2 to be a good but not transformative headphone, offering a slightly brighter and clearer sound than previous 600-series models, with improved sub-bass precision but not a significant overall upgrade. He is uncertain about recommending it at its $600 price, given strong competition and the availability of cheaper alternatives like the 6XX.
16:41The reviewer highly recommends the Sennheiser HD 660S2 as a reference-grade open-back headphone under $1000, praising its balanced, natural sound with excellent detail retrieval and imaging. While it requires a desktop amp to sound its best and has an intimate soundstage, it outperforms the original HD 660 and HD 600 in bass extension, resolution, and overall cohesion, making it a versatile choice for both studio and casual listening.
27:05The reviewer finds the Sennheiser HD 660S2 to be a comfortable, well-rounded headphone that improves on the original 660S with better bass extension and clarity, though it retains a warm, smooth sound rather than being bass-heavy. It's a solid all-rounder for most genres, but the build feels less premium for the price, and it requires adequate amplification due to its higher impedance.
16:20The reviewer finds the Sennheiser HD 660S2 to be a significant improvement over its predecessors, with a notably enhanced bass response, better technicalities, and a more complete sound, while retaining the beloved midrange warmth. They consider it a worthy upgrade that addresses past criticisms, though they note it still lacks a wide soundstage and is not the most impressive in that regard.
Summaries are AI condensations of each video's own conclusion, not transcripts. Titles, thumbnails and view counts belong to their channels.
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