Sennheiser HD 660 S



  • Sennheiser Audiophile Range
  • New transducer system developed by Sennheiser
  • Circumaural
  • Open
  • Dynamic
  • Two-sided cable routing
  • Maximum sound pressure level: 104 dB SPL @ 1 kHz, 1V RMS
  • Impedance: 150 Ohm
  • Frequency range: 10 - 41,000 Hz
  • Distortion factor at 1 kHz < 0.4
  • Weight: 260 g

Cables included:

  • 3 m cable with 6.3 mm jack
  • 3 m cable with 4.4 mm jack balanced
  • Adapter cable 6.3 mm jack to 3.5 mm jack
available since September 2019
Item number 471756
sales unit 1 piece(s)
Design Over-Ear
System Open
Impedance 150 Ohms
Frequency range 10 Hz – 41000 Hz
Adapter Yes
Replacable Cable Yes
Marrone/Argento Black
Sensitivity 104 dB
Type Of Connector Jack
Weight 260 g
Replaceable Cable 1
Color Black
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Immersive and detailled
Madelyn 05.02.2021
I bought this pair of headphones as a step up from a lower price bracket. I also own modded Fostex T50RP and Hifiman HE400i 2020. They were bought for home music enjoyment and I have been listening with them on an Ifi Zen Can and Schiit Magnius amplifiers. On both I find the sound extremely immersive - feeling like it is all around me, with enough separation to give interesting and absorbing detail but not a great deal of width. I am finding the most fun listening to rock and metal on the warmer Ifi which to my ear these headphones work particularly well with. Classical music can feel a bit heavy and claustrophobic on these for me but is still very enjoyable for the right composers!

Comfort is excellent even though the clamp is a little strong. I am not sure I'd want to wear them for too many hours. Even though they are open back they feel very enclosing.

They feel extremely well built, not heavy, and with a sleek, spare design. The pads are soft, and pleasantly textured. The whole headphone feels good to the touch and the materials refined and reasonably sturdy . The biggest drawback for me was the included cables being so long. If you listen at a desk be prepared to need to buy an alternative set.

I like them, a lot. They do demand that they be listened to so maybe less suitable for chilling out but for active listening they are wonderful. Very happy with my purchase and I would recommend the HD 660s to anyone looking for a (slightly) warmer, detailed and exciting headphone.


Great headphones, a little too hifi
The o'l razzle dazzle 09.12.2020
So i went for these as my new main mix headphones, because they have the 700 series driver with 600 series casing. Sound is clear, emphasising mids and highs. The sound is not as flat as i would desire, so coming from ns10-s i tend to scoop mids and boost highs more than is neccesary.

Combined with a crossfeed aux these are an amazing tool. And great for regular listening. If the sound was flat it would be my only mixing option, but for now il keep on referencing on other monitors.


Outstanding Quality All Round
LittleKing 28.06.2020
As a birthday gift for myself, I puchased these alongside a Focusrite Scarlett Solo and an AT2035. While certainly on the more expensive side, I went with these because of their relatively low impedance level (the Solo can only power phones up to 200 Ohms).

I would have to get incredibly nit-picky to find faults with the 660 S. The build is solid as a rock; they rest comfortably on my head for hours, which is helped by their open design; the presence and the space of the sound when listening to proper music or watching Blu-rays is incredible.

Certainly, matter of comforts and the type of sound you want are subjective. But these headphones are undeniably well-crafted. The only 'con' I suppose I could provide would be the price. However, you definitely get what you pay for here.


Warming Sound with details 24.03.2022
Good Sub-bass
Forward Mids
Smooth Treble
Warming Sound with great details and instrument separation
However, the plastic body and headband looks cheap and easy to get some scratches


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