Dive deeper into legendary sound.
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.
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?
 
Ever felt goosebumps from sound so real, it was as if the source was in the room with you? The non-fatiguing HD 660S2 gives people who love music an intimate way to connect more deeply with their favorite songs and artists. Breathtaking resolution and precision take you closer than ever to instruments and vocalists. Yet the sound is natural and balanced, never harsh or brash.
 
This warm, inviting signature combined with extended sub-bass makes listening uniquely pleasant and rewarding. And with comfort this good, it practically begs you to keep going for endless sessions. That’s how HD 660S2 combines the best of many worlds to give you an intimate experience you won’t want to live without.
 
Sub bass expands the entire sound
Double the sub-bass heightens your listening experience.
 
Traditionally, audiophiles don’t get too excited about sub-bass. It can easily get sloppy or boomy and become a distraction. And that’s a shame — because there’s so much more to experience here than just the gut punch of a kick drum. Did you know the low B of a 5-string bass vibrates at 30.9 Hz? Or that the lowest note on a concert piano comes in at 27.5 Hz? And of course, extended sub-bass makes bass-heavy genres sound fantastic, too.
 
And that’s the magic trick here. In doubling the sound pressure at the very lowest frequencies, we’ve nevertheless retained extraordinary precision and balance throughout the sub-bass, mid-bass, and beyond. Most impressive is how this affects the listening experience. Extension on the low end changes everything — by creating more space for the sound. Against a deeper backdrop, highs feel more brilliant, the soundstage deeper, emotions stronger.
 
Features
Uniquely powerful vented magnet system for minimized distortion
Ultra-light aluminum voice coil with 300-ohm impedance for excellent impulse response
Intimate sound with great timbre and deep, accurate sub-bass
Plush ear cushions and open design for maximum comfort
Outstanding quality designed in Germany, made in Ireland
 
They feel as great as they sound
Comfy slippers, your favorite jeans, the HD 660S2. Some things just feel awesome to wear.
 
The velour earpads of the HD 660S2 can only be described as a tactile pleasure. With just the right amount of tension for proper acoustic positioning and supple padding, the headband won’t draw attention away from your music, either. As an open-back design, the HD 660S2 gives your ears an extremely comfortable climate, even for super-long sessions.
 
The low total weight and ergonomic headband rule out any potential discomfort on top of your head as well. Combined with excellent build quality made in Ireland, you’ll quickly grow attached to a listening experience that’s as physically pleasing as the warm, non-fatiguing sound at its heart.
 
How do you one-up a line of legends?
Some of the most neutral headphones in the world are a tough act to follow.
 
The surround is now more compliant, too, dropping the resonant frequency to 70 Hz. Considerable effort also went into optimizing the airflow around the transducer. There’s more sensitivity over the entire frequency spectrum because the magnet's air gap works more efficiently now. Taken together, these measures result in even greater precision, speed, and resolution — with double the sound pressure at the lowest frequencies.
 
What’s in the box
HD 660S2 headphones
6.3 mm cable (1.8 m)
4.4 mm cable (1.8 m)
6.3 mm to 3.5 mm adapter
Carry pouch
 
EMOTIVE BASS AND POWERFUL RANGE
Sennheiser’s new HD 660S2 is an upgrade for audiophiles seeking exceptional detail with engaging low-frequency performance

Sennheiser's updated HD 660S2 expands the capabilities of the 600-series family, the longstanding benchmark for high-performance audiophile headphones. Sennheiser responded to the hi-fi community's feedback, crafting a headphone that skillfully balances reference-level detail with engaging frequency response. The headphone features a more dramatic listen with greater intensity from enhanced sub-bass tuning, extracting dynamic impact and emotion from audio enthusiasts' favorite recordings. The updated acoustics offer a delightful new way to experience music all over again.
 
"Our new Sennheiser HD 660S2 offers listeners what they requested most from the
headphones’ predecessor,” says Jermo Koehnke, Sennheiser Audiophile Product Manager.

“With precision and power like no other and new sensitivity across all frequencies, listeners will hear details they’ve never heard before, especially at the lower end of the spectrum.”

The depth and drama audiophiles crave
Improving on a beloved classic while retaining its best traits was a challenging task, starting with the lowest end of the frequency plot. The HD 660S2's warm bass characteristics pair perfectly with its silky-smooth treble performance and trademark vocal presence, allowing the timbre and uniqueness of any instrument part to stand out.

Across the entire frequency spectrum, the HD 660S2 delivers a refined listening experience thanks to improved transducer airflow and a refined voice coil. From thunderous timpani crescendos to pulsating EDM rises, even the most discerning audiophiles will notice the depth and nuance of low-frequency passages, adding dramatic flair to any type of music. Ultimately, listeners are treated to deeper, clearer bass without sacrificing the expansive detail the series is known for. By reducing the voice coil's weight, impulse response improves, bringing hyperrealistic textures to the forefront of any performance reproduction. The overall experience is smoother and warmer than the original HD 660S, thanks to a tuning that reduces the distances between select peaks and troughs. The overall impedance matches that of the HD 600 and HD 650, at an audiophile-friendly 300 ohms, for punchy dynamics and impressively low distortion.

A fit for the long haul
Designed in Germany and manufactured at Sennheiser's state-of-the-art Ireland production facility, the HD 660S2 continues the series' emphasis on quality, functional design using materials that contribute to the hi-fi experience. Plush earpads and cushy headband padding place the revised 300-ohm transducers at the optimal distance from the ear resulting in a spacious soundstage with an abundance of detail -- even for extended musical exploration. The transducer surround drops the resonant frequency from 110 Hz (original HD 660S) down to 70 Hz for hefty kick drums that move with ease. Even the outer mesh grilles are crafted to manage airflow at the ideal impedance for exquisite open-back listening sessions.