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Sennheiser HD 660s Audiophile Headphones - Discontinued

Product SKU: 508826

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Product Details

↓ Details provided by Sennheiser
(Specifications and appearance of this product are subject to change without notice)

HD 660S
The perfect blend of power and control.

The powerhouse open-back headphone

Connects you to the deepest corners of your music collection.

  • Hi-fidelity sound
  • Open-back design
  • 42mm transducers
  • Luxurious comfort
  • Detachable cable

A Direct Connection To Your Music

Known for their engaging signatures and liquid-smooth response, HD 660S predecessors HD 650 and HD 600 shattered performance barriers in the audiophile headphone category.

The HD 660S transcends the best of that storied DNA with supernatural speed and effortless instrument reproduction—even at the bookends of the frequency spectrum. Utilizing an all-new transducer and specially ventilated drive unit, the HD 660S delivers the revealing, tack-sharp detail audiophiles demand without sacrificing the engaging dynamics that make music so enjoyable.

From Our Ears To Yours

In just one listen you will understand why the HD 660S is so special. Thousands of listening sessions later its purpose is even clearer.

What you hear each and every time is the result of an open-back earcup mated to a new transducer tuned for the modern audiophile. Its speedy response is perfectly suited for reproducing those frequency-stretching recordings with confidence. Thanks to an aluminum voice coil, the 38mm diaphragm remains nimble for ultra-quick impulse fidelity across the board. This activation and rest behaviour unlocks the capability to communicate tonal and spatial characteristics precisely.

Meshing Together

The steel mesh found on the HD 660S drive unit is interesting in design but most impressive when it comes to performance.

It completes the ventilated driver, offering consistent control of air displacement to reduce turbulence. As a result, diaphragm travel is pure, letting the music—and only the music—shine in a perfect balance of integrity and expression. The steel composition allows for much tighter production tolerances, ultimately contributing to remarkably consistent characteristics of each HD 660S produced. When combined with the open-back earcups, the sound emanating from each transducer is completely free to expand, just as it would in nature.

Capability, Meet Versatility.

Today’s audiophile has more component choices than ever.

We optimized the HD 660S for efficiency on a wider range of devices to accommodate the varying levels of power present in output amplification circuitry. At 150 ohms, the HD 660S is the perfect partner for dedicated amplifiers, A/V receivers, and digital audio players (DAPs)—the magnet is more powerful than its predecessors, and thus easier to drive regardless of how your setup changes over time.

Handled with care

Every HD 660S has experienced a matching regimen to mate each transducer to its opposite-channel counterpart.

These tolerances are extremely narrow and when bolstered by automated assembly processes, ensure that your HD 660S experience is consistent with those all over the globe. We designed it with thoughtful, lightweight materials invisible to the acoustical system without sacrificing the durability needed for daily, all-day use. With a never-ending supply of music to consume, we wanted every touch point to be soft, luxurious, and durable for those extended listening sessions.

It's all about connection

We packed your HD 660S with a versatile set of essential cables, each one impedance-matched with ultra-low capacitance.

The ¼-inch / 6.3mm stereo connector offers the audiophile-standard plug for connection to devices such as headphone amplifiers and A/V receivers, digital audio players, analog gear, and more. A balanced, 4.4mm connector opens a pathway to a newer generation of balanced output devices (headphone amplifiers, digital audio players, etc.) that embrace this compact plug’s superior stability over time. A balanced headphone setup offers an even lower noise floor with great dynamic range when connected to balanced source/amp circuit outputs. The listener will thus experience a wider soundstage, tightly controlled transients and impossibly-clear instrument separation. Each cable is 9.8 feet / 3m long to accommodate unencumbered listening on gear deep within your shelves, or favorite listening chair, and a flexible adapter is included to reduce the 6.3mm to 3.5mm.


  • Transducer principle dynamic, open
  • Ear coupling circumaural
  • Frequency response (speaker) 9 Hz - 41,500 Hz
  • Sound pressure level (SPL) 104 dB (1 V)
  • Total harmonic distortion (THD) < 0.04% (1 kHz, 100dB)
  • Impedance 150 Ω
  • Cable length 3 m
    • Cables
      • stereo jack plug, gold-plated 1/4" (6.35 mm), unbalanced, 3-pin
      • 4.4 mm, balanced, 5-pin
    • Adapter 6.3mm to 3.5mm
    • Magnetic field 2.5 mT
    • Weight 260 g

    Product Reviews

    Sennheiser HD 660s Audiophile Headphones - Discontinued

    Customer Reviews
    4.8 Based on 20 Reviews
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    Filter Reviews:
    Ray M.
    United States United States


    Great experience with Audio46. Teams is great at 46 knowledgable staff great customer support and product arrives as described and timely. 660s is part of the lengendary 6XX line. 660s is a tweak on the design with an unchanged lush mid range and slightly tweak treble and bass. Looking for a phone that will not let you down. This is it.

    Mark U.
    United States United States

    Nice on Sale

    purchased for $350 thru this high quality purveyor. Definitely better than a 6xx — a bit more on the low end, bigger and more accurate soundstage, more musical with greater detail extraction. BUT as another reviewer stated, and like the 6xx, the clamping force is very real, and for myself not a comfortable ride for more than an hour or two. The balanced cable is a nice addition, but it’s extremely ordinary, and a high quality aftermarket would likely incrementally improve performance. Other reviewers find them very comfortable and you might too. Very engaging, accurate (not technical, with only the rarest of sharp edges at moderate volume) and spacious sound.

    Jerry H.
    United States United States

    HD 660S

    Awesome headphones! Thanks Audio46!

    Heng Y.
    United States United States

    Love it

    So far, loving it. Less fatigue from long-hours use, as compared to my previous closed-back HD280 Pro.

    Michael K.
    United States United States

    My dream come true

    Totally worth the bucks. I got mine on sale... Woot! woot!


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