Sennheiser HD 660S – Review

Sennheiser HD660 S

In this article we review the Sennheiser HD 660S. It sells for $499 USD


Disclaimer: The Sennheiser HD 660S was sent to us by Sennheiser directly in exchange for this review. Sennheiser is not related to Headfonia in any way.


Sennheiser has been around since like forever and they’re one of the most respected companies in audio. In the past, Sennheiser has positively surprised us with a lot of top quality products but this year the two most important product releases certainly were the closed HD800, called the HD820 and the HD 660S.

We’ve of course featured and reviewed Sennheiser products on multiple occasions and my personal favorite Sennheiser headphones are the HD650, the HD800 and the TOTL HE-1 (Orpheus). In fact the HD650 aka “The King” is one of my all-time favorite headphones tout court. No, the HD650 is not the very best headphone on the market, but it’s one that still and always brings me a lot of musical joy.

In today’s review we’ll be taking a closer look at the HD 660S, their new full sized, open headphone.


What surprised me most when Sennheiser launched this headphone, is the fact that they refer to it as the legacy of the HD650.

“The new HD 660 S is the ideal open, dynamic headphone for the passionate audiophile.”

If you look around on the web about HD 660S information, you’ll no doubt run into Jude’s post on Head-Fi where he shows the HD660 S driver compared to the one of the Sennheiser HD700. In that regard you would be inclined to say the HD 660S is rather related to the HD700 and not the HD600/650 series but I assume that it marketing wise is better to link the newest creation to the successful and iconic HD650. Anyway, you can find the HD 660S’ product page right here:

Sennheiser HD660 S

The Sennheiser marketing department tells us the following: The new model builds on the legacy of the HD 650, surpassing the exceptional performance of its predecessor with a new and improved transducer design that delivers lower harmonic distortion for an even more natural, lifelike audio experience. With a lower impedance of 150 ohms, the HD 660 S offers even greater versatility, allowing listeners to enjoy the headphones’ reference-class fidelity with both stationary and mobile HiRes players.

I first saw and heard the new HD 660S at the Headphone Heaven show in Rotterdam last year, after that premier it of course was present at every other show in the world and so far feedback has been mixed. I’ve talked to people who absolutely love them, while others just aren’t as enthusiastic about them. It basically all comes down to how you like the HD600 and HD650 and what you expect of the new HD 660S. Keep reading.


According to Sennheiser the new HD 660S features a new transducer design, resulting in improved control of the diaphragm movements thanks to a specially manufactured precision stainless steel fabric, which is adapted to the contour of the diaphragm.

The Sennheiser HD 660S also features extremely light aluminum voice coils that ensure the highest impulse fidelity. The HD660 S transducers are carefully selected and paired by hand to ensure consistently narrow (±1 dB) tolerances.

The HD 660S was launched with a special video and unlike you’d expect it doesn’t feature the typical marketing talk. Instead, Sennheiser found a creative way to explain what their newest product is all about. The video also features great audio and I absolutely recommend listening to it with a good set of headphones:


The Box, Accessories & Price

The HD 660S comes delivered in the typical Sennheiser box with cut-out foam. The headphones are beautifully presented as usual and for the price this is a really nice delivery. The box is a bit big though, so it like all the other boxes is in the attic, but if this was to be your only headphone, then I can see you using this box in your office or living room.

The price of the HD 660S is set at $499.95 (plus tax) in the United States while it’s being sold for €499 (incl. VAT) in Europe. For that price you get the nice box, the HD 660S headphone, a removable cable with a 1/4″ (6.35mm) plug, another removable cable with a 4.4mm balanced Pentaconn (5-pin) plug and a 1/8″ (3.5mm) to 1/4″ (6.35mm) adapter cable.

Sennheiser HD660 S

Sennheiser HD660 S


The HD 660S comes in a matt black and anthracite design – a high-end aesthetic that embraces both contemporary style and timeless elegance. You either like or hate the typical Sennheiser design but I think Sennheiser made a wise choice tuning the already existing design.

Design-wise the new Sennheiser HD660 S at a first glance just looks like the HD650 and HD600 headphones but at the same time it looks different enough to easily distinguish it from them. Basically the major differences are in the finish, grill and the driver design.

The Sennheiser HD600 saw the light in 1997 already and the HD650 followed back in 2003. In headphone terms that in theory basically means they’re ancient, but in reality their design is still very up-to-date. With the slight changes Sennheiser gave the HD 660S (basically it’s just the color and a different grill), the design is good for another 20 years, easily.

Sound and a lot more on Page TWO of this article, after the click HERE or by using the jump below

4.3/5 - (201 votes)

Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.


  • Reply April 3, 2018


    A sane and in a word balanced review. Kudos, Lieven.
    The best thing of the 660s to my mind is, besides of the psychoacoustic blended-ness, are its convenience factors so to say.
    First, it has all necessary cabling coming with it and you will just need an additional adapter f.i. 2,5 to 4,4mm balanced and then that is it. You arrived a high ends heavens gate.
    Second, it can be driven with stuff starting with a Dragonfly Red, iFi nano, Mojo etc. to certain satisfaction of even audiophile gourmets. This indeed is new in HD6.. land when until now you needed serious solid state or tube based gear, to be honest 🙂

    • Reply April 3, 2018

      dale thorn

      Great observations, you can’t lose with the 660s.

    • Reply April 4, 2018


      Thank you. That is definitely the case and I applaud the multi-cable thing 🙂

    • Reply May 30, 2018


      Indeed. 6-series sound without breaking the bank (too much).

  • Reply April 4, 2018

    Michel I

    Nice review again, Lieven, thank you.

    However, I don’t share your conclusion. The differences are small with the older HD600 and HD650, and there is a significant difference in street price: at this moment in Europe 429 Euro for the 660s but only 262 Euro for the 600, 315 Euro for the 650, and 435 Euro for the 700 (
    The balanced cable is exotic; most of us will need an adaptor or another cable to use it with our balanced headamps.
    The 600 is the best choice at this moment !

    • Reply April 5, 2018


      … then I still wonder : is the 600 the best choice when paired with portable sources, such as Mojo (single ended) and above all balanced with something like Hiby R6 (with a 2.5mm TRRS to 4.4 adapter) ?
      (if some people can comment on the results they get with HD600 or 650 with Mojo, you are welcome, as the reply from Musikverein lets me believe it’s maybe not ideal).

      • Reply April 5, 2018

        Michel I

        I think you need a good, powerfull amp for all the members of the 300 Ohm family, including the Massdrop x Sennheiser HD 6XX that you can buy this month on at 200 $ ( + 15 $ delivery outside the US), but also for the 150 Ohm 660s. The power of a Mojo is simply not enough.

  • Reply April 5, 2018


    Hi Lieven, great review!

    The review grabbed my attention when you mentioned: “With the Sony DAP, even in single ended mode, you get a warmer, slower sound which also is very musical. You get bigger bass, thicker mids and soft yet detailed treble”

    Although this is the NW-WM1Z, the bigger bass, thicker mids and soft detailed treble was exactly what I thought when I heard the NW-A45 compared to LG V20.

    Maybe one day Headfonia can review the NW-A45 and see if the implementation of the same digital amp stays faithful to the Sony sound signature for much cheaper 🙂

  • Reply April 5, 2018


    Thanks for another great review!! I have V281 and Senn HD6XX, which I love the paring but just sometimes I wish for more treble energy. I was torn between HD600 vs HD660S while I’m waiting for HD820 to be released. I have a sense that out of the balanced of V281, HD600 maybe the best out of three for my taste.

  • Reply April 6, 2018


    Recently treated myself to HD 660S to replace my aging HD 580 and paired it with the Massdrop Cavalli CTH + SDAC combo. Sounds great!

  • Reply April 18, 2018

    Dom Sweat

    Although I have yet to try a pair of open-back Sennheiser ‘phones I’ve heard nothing but good things about them.

    The Sennheiser HD 660s seem like a pretty good option for consuming the more spacious sound that these are well known for.

    Would these be a good entry level pair of open back headphones or would you suggest trying a less expensive pair at first?

    • Reply April 18, 2018

      dale thorn

      I wouldn’t go less expensive than entry level. The 660s is a great headphone, and how much you’ll like it will depend on many variables – your music, your source, your amp, etc.

  • Reply May 19, 2018


    its good headphones for games? which is better with better sound stage? Hd 660 s or Hd 700 ?

  • Reply June 22, 2018


    Lieven, for those looking for the smooth and slow sound with pronounced bass, but worth going for the 650 or would it be better to go for the new 660s and try a smooth signature amplifier to make the headphones more romantic?
    You say that with the right setting the 660s gets softer and with more pronounced bass, looking like the 650, so this 660s soft signature is nicer than the smooth natural of the 650?
    better go for the 650 that is smooth by nature or try to leave the 660s romantic using an amplifier that leaves its signature?

    • Reply June 24, 2018


      In that case I would still go for the HD650, as it does that best

      • Reply June 26, 2018


        Thank you Lieven! If the 650 is the only one with this smooth signature of the HD6xx line up to the 800s, sennheiser should not discontinue the 650. I almost sold my 650 recently to buy the 660s hoping for a smooth signature but easier to amplify. But the King is still king, I will continue with the 650, because it was the right choice of signature that I made, with the help of serious reviews like yours.
        The sennheiser 650 has been improving over the last 14 years, including the easiest to drive drivers and more compatible with multiple amplifiers, they also said the newer paint is more resilient.

  • Reply September 20, 2018


    Hi Leiven, thanks for this review. I’m considering getting some over ear headphones for when I travel overseas to replace my Shure SE425s. I listened mostly to classical music. Would the HD660 be a reasonable match with a Fit X5 2nd Gen DAP?
    Thanks for your help

  • Reply September 28, 2018


    Awesome review… Love Headfonia reviews. Any chance we will get a HD820 Review anytime soon?

  • Reply September 28, 2018


    Not sure when but yessssss

  • Reply October 9, 2018


    Thank you! Very informative. Any comparison to the LCD-2(C/F)? Both with Mojo as amp.
    Which is best for classical music?Piano, vocals, symphonies?

  • Reply November 29, 2018


    Thanks a bunch for this detailed review
    Do you think the KANN can be paired with this headphone?

    • Reply November 30, 2018


      Oh yes, though a bigger amp is always better

      • Reply December 1, 2018


        Thank you so much
        So this means I will definitely get it:)
        Thanks again

  • Reply March 22, 2020


    I want to buy hd650 + apogee groove or hd660s + apogee groove .
    Which one do you suggest ?
    I read hd650 is very demanding on amp , apogee groove can handle and drive it ?

    • Reply March 22, 2020


      I don’t think it does either justice, sorry

  • Reply November 27, 2020


    I have hd600 and hd650 that i love all these years. But HD660s have yhe goods of both of them with something extra ….imaging is just PERFECT.

  • Reply May 23, 2021

    Enzo Genaro

    Hace tiempo tengo ganas de estos auriculares, me parecen re lindos.
    Gran revisión muchas gracias.
    Una pregunta tengo el hiby R5 saber, crees que haga buen equipo con el HD 660s por la balanceada de 4.4 como uso portátil,

    • Reply May 23, 2021


      Could you please switch to English?

      • Reply May 26, 2021

        Enzo Genaro

        Great review thank you very much.
        I’ve been wanting these headphones for a long time, they seem so cute to me.

        One question I have the hiby R5 to know, do you think it makes a good team with the HD 660s because of the balanced 4.4 as portable use. ??

        do you think I get the benefit of that couple?


        • Reply June 4, 2021


          I don’t have the R5 here with me, but balanced most of the time is the way to go.

  • Reply March 12, 2022


    Hi Lieven, thanks for the great review!

    I’m kind of on the fence between the HD600 and this one… I listen to a lot of ambient/electronic music and currently use a Fiio Q3 as my main amp. Which do you think is the better choice for me?


    • Reply March 13, 2022


      I would recommend upgrading your amp for both of these. If not possible, the HD 600 S will be the best choice.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.