Skip Navigation

Sennheiser HD 660 S

Open-back over-ear headphones

2 Reviews

California customers: Please click here for your Proposition 65 warning.

Item # 143HD660S

Out of Stock

Ship date unknown Reserve risk-free

 Ships FREE

Add to Cart

Ask an expert

Our VA-based experts can help.




Our take on the Sennheiser HD 660 S

A classic revisited

Many of my Crutchfield co-workers credit Sennheiser's legendary "HD 600" series as their gateway into the world of truly high-end personal audio. These HD 660 S headphones keep the spirit of their stellar predecessors alive. But they feature a tweaked design and completely revamped driver system. The result is a smooth, timeless look and — more importantly — even greater musical detail. When paired with a high-performance headphone amp, you get great clarity with pinpoint imaging.  

Product Highlights:

  • over-the-ear design
  • open-back, metal mesh covered ear cups for spacious and transparent sound
  • latest model in Sennheiser's legendary HD600 series headphones
    • streamlined design with timeless matte black finish
  • we recommend a separate headphone amplifier for proper power and the best possible sound
Driver Design:
  • large dynamic drivers angled to create a more natural listening experience and a wider soundstage
  • cutting edge transducer design for tightly controlled diaphragm movement
    • diaphragm lined with stainless steel mesh for even airflow
  • lightweight aluminum voice coils ensure accuracy and fast transient response
General Info and Specs:
  • snug, cushioned fit
    • generous velour ear pads and soft headband padding
  • specially tuned 9-foot oxygen-free copper cable with balanced 4.4mm headphone plug
  • 9-foot oxygen-free cable with unbalanced 1/4" headphone plug
  • includes 3.5mm mini plug adapter
  • storage box
  • frequency response: 10-41,000 Hz (-10 dB)
  • sensitivity: 98 dB
  • impedance: 150 ohms
  • weight: 9.2 oz. (without cable)
  • warranty: 2 years
  • Our 60-day money-back guarantee

What's in the Box:

  • Over-ear headphones with 10' audio cable (1/4" plug)
  • 9" Adapter (1/4"-to-3.5mm)
  • 10' Balanced audio cable (4.4mm Pentaconn)
  • Hinged storage box
  • Instruction manual

Sennheiser HD 660 S Reviews

Average Customer Review(s):

(2 Reviews)


Martin from Marshall, MI on 11/12/2018

Crutchfield Customer Review (What's this?)

I've owned the Sennheiser HD650 for about a decade and have enjoyed it greatly. Even though this new headphone is not yet broken-in, I could still hear a noticeable improvement over the HD650. The 650 had a somewhat veiled sound and the high frequencies were somewhat muted. Both of those shortcomings seemed to have been corrected in this new model. I look forward to even better sound once I rack up more hours of listening.

Pros: Clean sound Excellent dynamics Highly detailed

Cons: None

Love the Sound!

James from Seattle, WA on 3/14/2018

Crutchfield Customer Review (What's this?)

I am amazed with the sound and comfort of this headphone. This is my first higher end headphone, but I have had a Grado SR80 and Sennheiser HD 280 pro. The clarity and presence is amazing. I listen through a Schiit stack of Modi/Magni to lossless files - but it took these headphones to really bring them to life. Listening through un-amped (iPad/iPod) sources does not shine as well, but still superb. The sweet spot seems to be in the midrange - vocals on some tracks are so much clearer in the mix. Some reviews mention the treble is brittle, but i'm not hearing it. But I'm also at the age where that might not be a problem :-). Very happy with this purchase!

Pros: Midrange clarity, great sound balance. Comfortable fit.

Cons: Best with amplification due to higher impedance.


Hands-on research

Features and Specs

Earcup Type Open
Earcup Width x Height 3.252" x 4.288"
Noise-canceling No
Bluetooth No
Mic For Taking Calls No
iPhone Control No
Lightning Connector No
Android Control No
Frequency Response 10-41k Hz
Sensitivity 104 dB
Impedance 150 Ohms
Weight 12.3 ounces
Cord Length 120" + 120
1/4-inch Adapter Included No
Volume Control No
Parts Warranty 2 Years
Labor Warranty 2 Years

Product Research


Overview: The Sennheiser HD 660 S high-end headphones feature an open design to give you an exceptionally natural, spatial, and accurate sound. Unlike closed, noise-isolating earcups, the HD 660 S's earcups have a specialty steel mesh, molded to the natural shape of the acoustic chamber, to provide an open environment. The HD 660 S features new, lower-impedance drivers with extremely light aluminum voice coils. The transducers are matched within +/- 1dB tolerances for consistent sound. The headphones come with two 10' cables, one with the new 4.4mm balanced connector, and a hinged storage box.

Angled Transducers: The HD 660 S has angled transducers to resemble the perfect positioning of a pair of reference monitors to put you in the center of the sweet spot. The ear cups are elliptical to follow the shape of the outer ear, with plush, velour-covered padded ear cushions for hours of listening comfort.

Headphone Cables: The HD 660 S comes with two interchangeable, 10-foot cables. One cable has a full-sized 1/4" plug. A 1/4"-to-3.5mm adapter is included for listening to portable devices. The other cable (also 10') is terminated with a new 4.4mm Pentaconn balanced connection that can be used with some high-end digital audio players (such as the Sony TA-ZH1ES) and headphone amplifiers (including the Sennheiser HDV 820). Both cables are constructed with OFC copper (oxygen-free copper) with its high conductivity for best signal transfer. The cable's outer jacket is coated to greatly reduce handling noise.

Storage Box: The HD 660 S has a sturdy, hinged box with cut-out foam padding for storage of your headphones and attached cable.


  • Frequency Response: 10-41kHz
  • Nominal Impedance: 150Ω
  • Sound Pressure Level (1 kHz/1V): 104dB
  • THD + N (1kHz/100dB): <0.04%
  • Maximum Input Power: 500mW
  • Weight: 9.2 ounces (w/o cable), 12.5 ounces (w/cable)

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Staff Reviews

Product reviews from the Crutchfield Labs

What are the Labs?
Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

These headphones have a balanced output jack and can meet my needs better. [ Arthur  Nov 21, 2018 ]
Own other Sennheiser headphones [ MICHAEL  Apr 07, 2018 ]
Longtime fan of closed back headphones, owner of ATH M50x and ATH M70x looking for the transparency of an open back system. [ Richard  Feb 28, 2018 ]
reviews [ PETER  Jan 30, 2018 ]