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Sennheiser HD660S Review (Headphone)

Rate this headphone:

  • 1. Poor (headless panther)

    Votes: 15 7.2%
  • 2. Not terrible (postman panther)

    Votes: 66 31.7%
  • 3. Fine (happy panther)

    Votes: 103 49.5%
  • 4. Great (golfing panther)

    Votes: 24 11.5%

  • Total voters
    208

ichliebes

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Mar 28, 2022
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Hey Duke, thank you so much for your reply.

I see this is Parametric EQ settings for HD650 to Harman Target (from AutoEQ, with measurements from Oratory1990).

I was wondering If I could make 660s sound similar to what 650 did after equalizedwill try to figure it out.

My main problem with 660s is that it sounds not smooth enough, sometimes the high frequency sounds like broken glass... And overall the bass sounds strange.

Update: just find out I can use autoeq.py to make a headphone sound like another. Will try it tomorrow.
Tried that "Using Sound Signatures" feature of autoeq.py, the result is not satisfying.

Good news is, I reinstalled the earpads of 650 and two channels are now balanced. Still can't choose between 650 and 660S cause after more listening, I feel like they have both advantages and disadvantages.
 

DUKE-DUKE

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Tried that "Using Sound Signatures" feature of autoeq.py, the result is not satisfying.

Good news is, I reinstalled the earpads of 650 and two channels are now balanced. Still can't choose between 650 and 660S cause after more listening, I feel like they have both advantages and disadvantages.
Hello.

I tried equalizations both of models of the same brand as my headphones and of different brands and models that had nothing to do with the brand of my headphones, so it's just a matter of trying presets until you find the one you like the most.

I'm glad the new ear pads did a good job.

Getting used to the sound of a headphone is a process in which you should not be in a hurry, nor should you become obsessed with it.

Headphone manufacturers make a living out of selling us the same product over and over again by modifying the look and sound signature, and the tactic almost always works.

Equalizing the headphones to the taste of each one they finish the hypnotic business that they have mounted.

This is my subjective opinion.

Regards.
 

AML

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Jun 22, 2021
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Location
Yokohama, Japan.
I had these for a while, but found them to be too veiled for my taste. Good mids though. I replaced them with Focal Clears (non MG) which have better sound stage and clarity but still maintain that intimacy of the HD660s and great mids.
 

ichliebes

Member
Joined
Mar 28, 2022
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Tried that "Using Sound Signatures" feature of autoeq.py, the result is not satisfying.

Good news is, I reinstalled the earpads of 650 and two channels are now balanced. Still can't choose between 650 and 660S cause after more listening, I feel like they have both advantages and disadvantages.
And I returned 650... Cause 660 has more clarity and better soundstage. For sound signature, I prefer 650 more. Is there some headphones with the clarity of 660 but sound like 650? I read about R70x but it seems like it's fragile.
 

Limopard

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Apr 22, 2021
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Location
Germany
Nice headphone, but a tad below my favourites 600/650 (for me). Plus: The 560s is a strong contender, when a lower impedance is needed - for a much lower price. It looks and feels less fancy, though.
 

lc155

Active Member
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Nov 9, 2018
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It's like phone reviews, where people say "this isn't much different to the last phone". Yes, you're not supposed to buy every phone a manufacturer brings out! I bought this to replace my HD 595. It's a bit better than those headphones!

How long were you using those 595s for? Were they even intact by that point or held together by tape?
 

threni

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How long were you using those 595s for? Were they even intact by that point or held together by tape?
About 12 years. They had some cosmetic damage (the headband padding had some cracks) and the plastic where you alter the size had a hairline crack on each side, and the earpads were worn and rather flat, so I sorted that out. Structurally they're fine and they sound as good as when I bought them. I actually use them more now than ever before; I bought HD 660S and was going to move that system around the house as it's a pretty small setup but that got old pretty quick so I created a second tiny portable moOode system using a Pi Zero and the Apple USB dongle and use that with the 595s. They're great.
 

Marcus X

New Member
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Aug 18, 2022
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This is a review and detailed measurements of the Sennheiser HD660 S open-back headphone. It is on kind loan from a member and costs US $400.
View attachment 211584
You would be hard pressed telling it apart from the similarly numbered Sennheiser headphones which is not a bad thing.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few kilohertz so keep that in mind as you read these tests. If you think you have an exact idea of a headphone performance, you are likely wrong!

Fitment on the fixture was easy.

Sennheiser HD660 S Headphone Measurements
As usual we start with the headphone frequency response as comparison to our preference curve:
View attachment 211585

We have our typical loss of bass response and deficiency in lower treble which likely quashes its spatial qualities. Not sure what is up with that peak resonance above 5 kHz. EQ is mandatory and here is the graph to build from:
View attachment 211586

Distortion is similar to other Sennheisers being dominant in bass:
View attachment 211587

View attachment 211588

The redesign from HD650 seems to have been to lower the impedance:
View attachment 211589

This is half as much, reducing the dependency on high output voltage from the amp (i.e. making it more mobile friendly). Sensitivity is average:
View attachment 211590

Group delay is messy:
View attachment 211591

Sennheiser HD660S Listening Tests and Equalization
Out of the box sound was very good, proving that you need to EQ (or compare to another neutral headphone) to know what you are missing. After inserting three filters, I was shocked how much the tonality and overall fidelity improved:
View attachment 211592

The bass boost is self explanatory. The middle filter made a substantial improvement to its spatial qualities which was a delight to listen to now. The last filter doesn't make a tonal difference but seems to have the effect of lowering distortion.

I had an easy time driving the HD660S with my RME ADI-2 DAC. It sounded superb (with EQ) up to reasonably loud levels. Above that I thought the bass became less distinct but that was not safe or long term listening level.

With the EQ I sat back and enjoyed the sound with track after track. Turn it off and sound collapses with a more mundane but not annoying tonality.

Comfort was great compared to my much heavier everyday headphone. But after half hour the tips of my ears were starting to become uncomfortable a bit.

Conclusions
The core DNA of this line of headphones from Sennheiser seems to be maintained in this revision. Response is a bit more rough than HD650 but both need EQ anyway. And with it, you have a very top performing headphone.

I am going to put the Sennheiser HD660S on my recommended list.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Thank you for your excellent reviews. I'm beginner as to headphones, so I would like to ask you, how to solve EQ, if I buy f. e. these phones together with Topping D90SE and A90 Discrete? I suppose that these products don't have equalization in house. (I will use them expecially for listening classical music from TIDAL and from transport Pro-Ject CD Box RS2 T, which allows connection I2S connection with Topping D90SE.) Thank you very much for your advice.
 

usern

Senior Member
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May 31, 2020
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Thank you for your excellent reviews. I'm beginner as to headphones, so I would like to ask you, how to solve EQ, if I buy f. e. these phones together with Topping D90SE and A90 Discrete? I suppose that these products don't have equalization in house. (I will use them expecially for listening classical music from TIDAL and from transport Pro-Ject CD Box RS2 T, which allows connection I2S connection with Topping D90SE.) Thank you very much for your advice.
Do you use Tidal from a PC? If so, then you can use Equalizer APO on Windows, https://rogueamoeba.com/soundsource/ for Mac.
 

neuron

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Nov 4, 2022
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If I could get the HD660S, the HD650, or the HD600 for the same price, is there a recommendation from this group? I would be using them with a Topping DX3 Pro+.
 

Robbo99999

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If I could get the HD660S, the HD650, or the HD600 for the same price, is there a recommendation from this group? I would be using them with a Topping DX3 Pro+.
Get the HD560s & EQ it instead! :)
 

MacCali

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Dec 21, 2020
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If I could get the HD660S, the HD650, or the HD600 for the same price, is there a recommendation from this group? I would be using them with a Topping DX3 Pro+.
You need to demo them to see which one you prefer honestly. I personally prefer the 600 over both the others, but that’s not going to provide the answer you need
 

enricoclaudio

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I did demo the 650s and 660s at the same time. Ended sending back the 650s. To my ears, the 660s sound better than the 650s. However, you will find others that would say the contrary so my advise, get both and keep the one you like the best.
 

D00M

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Jun 25, 2022
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I have 560s for gaming and 660s for music. 560s is a bit bright, which can be fixed by EQ. EQ cannot fix or change other factors.

560s has larger soundstage. No EQ can change 660s to match the soundstage.

On other hand, 660s has more instrument separation; there are many layers to the imaging; sound 3d (though smaller in size). Cannot match that on 560s.

Except for sound stage, i prefer 660s over 560s.
 

Merkurio

Active Member
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Jul 18, 2018
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I have 560s for gaming and 660s for music. 560s is a bit bright, which can be fixed by EQ. EQ cannot fix or change other factors.

560s has larger soundstage. No EQ can change 660s to match the soundstage.

On other hand, 660s has more instrument separation; there are many layers to the imaging; sound 3d (though smaller in size). Cannot match that on 560s.

Except for sound stage, i prefer 660s over 560s.

Which EQ parameters are you using on both?
 

D00M

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Jun 25, 2022
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Which EQ parameters are you using on both?
I start with Oratory's EQ. Then adjust to my preference.

Frequency, Gain, Quality, Filter
34, 3, 1.5, Peak
100, 5.5, 0.71, Low shelf
200, 0, 0.8, Peak (zero'ed from Oratory)
1330, 0, 1.8, Peak (zero'ed from Oratory)
1770, 2, 0.71, High shelf (reduced from Oratory)
3300, -1, 1.7, Peak (increased from Oratory)
5520, -3.2, 3.8, Peak (increased from Oratory)
8000, 3, 1.4, Peak
10000, 1, 0.71, High shelf (increased from Oratory)
 

isostasy

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Oct 19, 2022
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I recently got hold of an old HD265 Linear for only £25. They have a black paper screen. I took the backs off, put some new foam in the spider and installed new Sennheiser velour pads to see how they'd compare with my HD6XX:

HD265.jpg


I do not have a HD660S to compare directly, unfortunately, but it is interesting to see a similar roll off in bass, a 2-3dB recession between 2-4kHz, and some dips in treble compared with the HD6XX, like a HD660S. No peak between 5 and 6kHz however.

Subjectively they are actually very difficult to tell apart. The resolution set on the Y axis above makes deviations very noticeable, but really they are never more than 3dB away from each other unless you include the odd dip in the right channel around 7kHz.

The HD265 and new pads came to £57. A super budget HD660S? Probably not, but we'd need someone to put them on a GRAS to perform a real comparison. I have no plans to get hold of the HD660S myself.
 
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