The Sennheiser HD 660s2 is the kind of headphone a person should buy when he is tired of chasing gimmicks and want to enjoy their music properly and smoothly. It is an open-back, wired pair made for quiet spaces such as late nights, long playlists, and a bit of focused listening at your desk. There are no apps, no ANC, no ‘smart’ tricks. Sennheiser has taken the older HD 6605 and tuned it a little differently with a fuller low end and smoother, more relaxed presentation.
In the hand, the HD 660S2 feels familiar to other Sennheiser classic designs. It is light, mostly plastic, and clearly built for comfort rather than for showing off. Once it is on the head, the headset almost disappears, allowing music to take centre stage. Vocals mix naturally, instruments have their own space and small details in the track are easy to notice without the sound becoming sharp or tiring over time.
Design and Build Quality of the Sennheiser HD 660S2
The HD 660S2 is built and classically in a look that doesn’t demand attention. The frame is mostly lightweight plastic, with just a touch of metal to give it strength; thus, it feels solid without being heavy.
The ear cups are large enough to cover the whole ear and are made of soft velour, which provides a gentle feel when put on. It makes long listening sessions comfortable with no tight spots or heat buildups.
The headband is padded enough to stay in place without feeling snug or uncomfortable. The open back design is not only for looks; it provides plenty of space for sound to breathe, creating a natural, airy feel. The cables are detachable, which makes swapping out easy if needed. Everything about the HD 660S2 feels thoughtful and practical. It is not flashy, but it also doesn’t need to be. The main focus is on comfort, durability and letting music do all the talking.
Sound Quality: What Makes the Sennheiser HD 660S2 Stand Out
The sound quality of HD 660S2 feels so amazing, natural and effortless, almost like the music is happening live in the room. Nothing is exaggerated; the bass is tight but not overpowering, the mids are clear and present, and the highs remain smooth and detailed without ever being harsh.
Vocals feel open and surprisingly realistic, thus every word or note can be heard clearly. Instruments have enough space around them, making it easy to notice subtle layers like the brush of a cymbal or the faint pluck of a guitar string.
The HD 660S2 performs beautifully across genres like acoustic, jazz, and classical. As a result, the music sounds rich and full, while pop and electronic tracks maintain clarity without sounding flat. Pairing these headphones with a good amplifier or DAC enhances their performance even more by bringing out subtle details and textures that are hard to notice on other headphones. In short, it is built for people who want music to feel natural, open, and fully alive.
Pros:
- Very natural, balanced sound with clear mids and smooth highs.
- Open-back design gives a spacious, airy listening experience.
- Comfortable for long listening sessions thanks to soft velour earpads and a well-padded headband.
- Lightweight yet sturdy build ensures durability without feeling heavy.
- Detachable cables make replacements or upgrades easy.
- Excellent instrument separation and detail retrieval, especially for acoustic, jazz, or classical music.
Cons:
- An open-back design means no noise isolation, which is not suitable for commuting or noisy environments.
- Wired-only connection; no Bluetooth or wireless option.
- Lacks active noise cancellation or modern smart features.
- Requires a decent DAC or amplifier to reach full potential, especially for high-resolution music.
- Bass is controlled but not emphasised, which may not appeal to listeners who prefer heavy low-end.
Comparing the Sennheiser HD 660S2 to Other Models
The Sennheiser HD 660S2 holds a unique spot in Sennheiser’s lineup. Compared to the HD 560S, it offers fuller low end and a slightly warmer, more balanced sound, thus making it more engaging for everyday listening. While the 580S is excellent for neutral, analytical listening, the 660S2 adds a touch of richness that makes music more alive.
Compared to the HD650 or HD660S.The 660S2 improves clarity and instrumental separation. The treble is smoother, reducing potential sharpness during long listening sessions. It makes it a better choice for people who desire both comfort, natural and immersive sound.
On the other hand, Momentum 4 wireless focuses on portability, wireless convenience and active noise cancellation. The HD 660S2 is designed for home or quiet space listening.
It does not compete in features like ANC or Bluetooth, but it excels in delivering pure, detailed sound that headphones like the Momentum series can’t match in neutrality and openness. Overall. The HD 660S2 is for listeners who want a balanced, spacious and comfortable experience.
HD 660S2: Worth the Hype and the Cost?
The HD 660S2 has a reputation among headphones for a reason. The sound is natural, balanced and detailed, giving the music a sense of space and realism that very few headphones in this range can match. Comfort and build make long listening sessions enjoyable, with soft velour earpads and a lightweight frame that never feels tiring. While it does not include wireless connectivity or noise cancellation, the focus on pure, honest sound makes it stand out for serious listeners.
Compared to other Sennheiser models. The HD 660S2 improves clarity and smoothness, making instruments and vocals feel more lively. Pairing it with a good amplifier elevates the experience by bringing out subtle details and textures. This model justifies its price through performance.
Final Verdict.
Sennheiser HD 660S@ focuses on the things that really matter, such as sound quality, comfort and durability. The evenly balanced natural audio creates a sense of being in a live music setting with clear articulated vocals. Well delineated instruments and an airy, wide open soundstage. Long listening sessions stay comfortable as soft ear pads and a lightweight frame see to it that even the solid build means they last for years.
It lacks wireless connectivity, noise cancellation and other fancy features, but the HD 660S2 really shines when it comes to pure and immersive listening. Compared to its brethren, it provides smooth highs, improved instrument separation and a fuller low end, making it an excellent choice for serious music lovers. From home to quiet spaces, it proves to be well worth the investment.