Sennheiser
Dive deeper into legendary sound.
HD 660S2 Audiophile Headphones
Nothing makes music feel dramatic like powerful bass. The extremely precise yet non-fatiguing sound of the HD 660S2 now delivers even more impact with extended sub-bass.
Our engineers optimized the HD 660S's surround, transducer airflow, and coil to double the sound pressure at the lowest octaves. You can feel the lowest note on the piano (27.5 Hz) or the bass drum kick (45-60 Hz) as if you were there.
The relaxed tone and open-back design make these extremely comfortable headphones great for long sessions. With warm tuning, smooth treble, and strong bass, the standard setter for extended listening is now the standard-setter for extended bass.
Tech Specs
- Headphone Type: Wired Over-Ear
- Connection Type: 4.4 mm plug (balanced); 6.35 mm plug (unbalanced)
- Impedance: 300 Ω
- Driver Diameter: 38mm
- THD: <0.04% (100 dB, 1 kHz)
- Sound Pressure Level: 104 dB (1 V)
- Frequency Response: 8Hz - 41.5KHz
- Acoustic Principle: Open-back
- Ear Cushion Material: Velour
What's in the box
- HD 660S2 headphones
- 1.8 m cable with 4.4 mm connector (balanced)
- 1.8-meter cable with 6.35 mm connector (unbalanced)
- Flexible 6.35 mm to 3.5 mm adapter
- Storage pouch
- Documentations
HD 660S2
Enjoy 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.
Features
Here are the reasons why?
- Extended sub bass
- Natural, warm sound
- Comfortable open-back design
Your new desert island headphone
Every high-end headphone has its own unique personality. What if you could only own one?
The HD 660S2 delivers lifelike, intimate sound that brings you closer to your music. With warm, balanced tones, extended sub bass, and exceptional comfort, it offers a deeply rewarding listening experience—perfect for endless sessions.
Sub bass expands the entire sound
Double the sub bass heightens your listening experience.
Audiophiles often avoid sub bass for fear of muddiness—but done right, it adds depth and emotion. The HD 660S2 doubles low-end sound pressure while preserving clarity and balance. The result? A richer soundstage, more vibrant highs, and a truly immersive experience.
They feel as great as they sound
Comfy slippers, your favorite jeans, the HD 660S2. Some things just feel awesome to wear.
The HD 660S2’s velour earpads and lightweight, ergonomic design offer exceptional comfort for long listening sessions. With open-back breathability and premium build quality from Ireland, it’s as pleasing to wear as it is to hear.
How do you one-up a line of legends?
Some of the most neutral headphones in the world are a tough act to follow.
Building on the legacy of the HD 600, 650, and 660S, the HD 660S2 refines that iconic sound with a new 300-ohm coil, improved airflow, and enhanced transducer design. The result: greater precision, speed, and twice the sub bass power—while staying true to its balanced roots.
Frequency response curve
Describing the HD 660S2 sound
Increased SPL
Between 20-200 Hz, the sound pressure level is significantly increased (twice the sound pressure at 20 Hz), which results in a much better impact of percussion and electronic music.
Stronger Response
Above 5000 Hz, overall, the response is stronger, which results in more perceived clarity.
Smoother Response
Above 5000 Hz, the response is “smoother”.
The difference between the louder peaks and quieter troughs is smaller, music reproduction is more natural, and fewer peaks mean less fatigue during long listening sessions.
More Information
What you need to know
The sound of the HD 660S2 can be best described as ...
The HD 660S2 produces a natural, relaxed sound so you can enjoy a listening experience with great timbre and deep, accurate bass.
Which of these SOUND features does the HD 660S2 have?
- Audiophile sound
- Warm bass-empathized tuning
- 42 mm high-performance transducers
- Aluminum voice coil
- Open-back earcups
To connect to an audio source the HD 660S2 cable/s have what type of plug/s?
The unbalanced 6.35 mm plug and the balanced 4.4 mm plug lets you connect to a multitude of audio devices. A flexible 6.35 mm to 3.5 mm adapter is also included for additional connection options.
The HD 660S2 has an impedance of ...?
The HD 660S2 has an impedance of 300 Ω (Ohms) that is optimized to reproduce audio with greater detail and speed to unleash the potential of serious audiophile systems.
Which of these COMFORT features does the HD 660S2 have?
- Elliptical earcups
- Velour earpads
- Ergonomic headband
- Light weight chassis
- Detachable cables
Does the HD 660S2 have an undampened magnet hole?
Yes, The HD 660S2 has an undampened magnet hole which allows the diaphragm to move freely for optimized impulse response.
Does the HD 660S2 utilize channel matching?
Yes, Channel matching is used during production to provide excellent balance and superior imaging through matched acoustic systems.
Which of these CRAFTSMANSHIP features does the HD 660S2 have?
- German design and engineering
- Outstanding build quality
- Optimized airflow
- Channel matching
Where is the HD 660S2 designed and engineered?
The HD 660S2 is designed and engineered in Germany and made in our Audiophile Production facility in Ireland.
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