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"Immersive sound quality in sleek design"

Sennheiser HD 660 S Review

Experience exceptional sound quality and comfort with the Sennheiser HD 660 S. This high-end open-back headphone offers a balanced and natural sound signature, a spacious soundstage, and top-notch build quality. Perfect for audiophiles seeking the best audio experience.

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Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S
Sennheiser HD 660 S

The Sennheiser HD 660 S is a high-end open-back headphone that promises to deliver exceptional sound quality and comfort. With its sleek design and premium build, this headphone is targeted towards audiophiles and music enthusiasts who demand the best audio experience.

Sound Quality

When it comes to sound quality, the HD 660 S does not disappoint. It offers a balanced and natural sound signature that is both detailed and accurate. The bass is tight and controlled, while the mids are clear and well-defined. The highs are smooth and extended, without any harshness or sibilance.

One of the standout features of the HD 660 S is its soundstage. The open-back design allows for a spacious and immersive listening experience. Instruments and vocals are placed accurately, creating a realistic and three-dimensional soundstage.

However, some might find the sound signature of the HD 660 S to be slightly analytical and lacking in excitement. The emphasis on accuracy and neutrality might not appeal to those who prefer a more colored or bass-heavy sound.

If you like this review, you might also like our review on the Sennheiser HD 25 Plus or Sennheiser Momentum 4 Wireless.

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Build Quality

The build quality of the HD 660 S is top-notch. It features a sturdy and durable construction with high-quality materials. The headband and ear cups are made of metal, giving the headphone a premium feel. The ear pads are plush and comfortable, allowing for long listening sessions without any discomfort.

One minor drawback is that the headphones do not fold or collapse, making them less portable compared to some other models. Additionally, the cable is non-detachable, which can be inconvenient if it gets damaged or if you prefer using a different cable.

Sennheiser HD 660 S

Battery Life

As the HD 660 S is a wired headphone, it does not have a battery and does not require charging. This is a significant advantage for users who do not want to worry about running out of battery power during their listening sessions.

Sennheiser HD 660 S


The HD 660 S is not designed for on-the-go use. Its open-back design leaks sound and does not provide any isolation from external noise. This makes it unsuitable for use in noisy environments or during commutes. It is best suited for use in a quiet room or studio where you can fully appreciate its sound quality.


While the HD 660 S does not come with any fancy features or active noise cancellation, it excels in its primary function - delivering exceptional sound quality. It does, however, come with a detachable 3-meter cable, which provides flexibility in terms of cable length.

Sennheiser HD 660 S


The HD 660 S has a sleek and understated design. It features a matte black finish with silver accents, giving it a sophisticated and timeless look. The headphone is not flashy or attention-grabbing, making it suitable for both casual and professional settings.

What's in the Box

The HD 660 S comes with a hard-shell carrying case, which provides excellent protection during transport. It also includes a detachable 3-meter cable and a 6.3mm stereo adapter. While the included accessories are minimal, they are sufficient for most users.

Sennheiser HD 660 S

Comparison to Competitors

When comparing the HD 660 S to its direct competitors in the same price range, such as the Beyerdynamic DT 1990 Pro and the Audio-Technica ATH-R70x, the HD 660 S holds its ground. While each headphone has its own strengths and weaknesses, the HD 660 S offers a more balanced and natural sound signature compared to the slightly brighter and more analytical sound of the DT 1990 Pro. The ATH-R70x, on the other hand, has a wider soundstage but lacks the same level of detail and accuracy as the HD 660 S.

Video by: The Headphone Show


The Sennheiser HD 660 S is a high-quality headphone that delivers exceptional sound quality and comfort. Its balanced and natural sound signature, along with its spacious soundstage, provides an immersive listening experience. The build quality is top-notch, although the lack of foldability and non-detachable cable might be minor inconveniences for some. Overall, the HD 660 S is a solid choice for audiophiles and music enthusiasts who prioritize sound quality above all else.

Pros & cons


  • Highly accurate and detailed sound reproduction
  • Comfortable fit for long listening sessions
  • Wide soundstage for an immersive listening experience
  • Detachable cable for easy replacement and customization
  • Sturdy build quality for long-lasting durability


  • Expensive compared to other headphones in its class
  • Not as portable or compact as some other models
  • May require a separate amplifier to reach optimal sound quality
  • Not ideal for bass-heavy music genres
  • Ear cups can get warm during extended use

Technical specifications

Product Name Sennheiser HD 660 S
Headphone Type Over-ear
Driver Type Dynamic
Impedance 150 ohms
Frequency Response 10 Hz - 41 kHz
Sound Pressure Level (SPL) 104 dB
Total Harmonic Distortion (THD) <0.04%
Ear Coupling Circumaural
Cable Length 3 meters
Connector 6.35 mm stereo jack plug
Weight 260 grams