Sennheiser HD 660 S Over-Ear Open Headphones Page 2


Sound Quality
On a gross level the HD 660 S sound is similar to the HD 600 and 650. Zooming in a little closer I'd characterize the HD 650 as the warmest of the bunch and the HD 660 S the brighter of the trio. Overall, I'd characterize the HD 660 S as a little lean.

To my ears this comes from two things: The HD 660 S has less of a broad upper-bass centered hump it's virtually flat from 100Hz to 1kHz, and the bass falls off gradually below 100Hz. But I also hear a more forward presence region from 1kHz to 3kHz. To my ears the HD 650 (in stock form) does warrant the "veil" designation; the HD 600 a little; and the HD 660 S not hardly at all.

Imaging on the HD 660S does appear to be a bit deeper and wider, but it's mostly quite like the other two headphones, which to my ears is good reasonably wide, and not particularly deep. The HD 660 S also appears to have more impact. You'll notice I used the word "appear" in both those descriptions. There's a reason for that...

The biggest difference I hear when switching from the HD 660 S to one of the other two, and I heard it immediately, is the fairly significant sense of a smoother and more refined sound of the previous cans. Switching back to the HD 660 S I hear it as grainy more more edgy in comparison. I'm quite saddened by this.

The HD 600 and HD 650 have for well over a decade been considered one of, if not the best headphone available. They are legend! Right on the HD 660 S box it says, "The Legend Continues." Sadly, I think they are mistaken. Right off the bat, this graininess takes it out of the family's rightly earned status.

But it gets worse. One of the defining characteristics of the HD 600/650 is a wonderfully smooth response. I had the good fortune once of sitting right in the circle with the Muir String Quartet and I was simply breathless with the absolutely smooth nature of the sound. Reproduced violins can take on a screechy character; in real life they are not at all. The HD 600/650 does a great job of portraying this smoothness. Very good treble response should give the impression of smooth detail. So many people mistake a bright, sizzly response for good detail. It just ain't so.

The smooth detail of the 600/650 allow them to "scale" well, bringing out the advantages of upstream gear. I tried the the three headphones with my HeadRoom Max, Bottlehead Crack, and Simaudio 430HA amplifiers. The differences were readily apparent with the 600/650, but was much less so with the HD 660 S. The grainy character got in the way.

While the HD 660 S was a bit brighter than the other two, it also lacked the nuanced resolution and dynamic balance of the 600/650. Low level details were lost, and grosser detail seemed compressed into a similar level of response. My measurements show these cans as far more similar than they actually sound to the ear.

To make matters worse, the design of the HD 660 S driver makes them less able to be modified by DIYers. Ugh.

What the...
I just don't understand what Sennheiser was trying to accomplish with these headphones. The intro to their product page says right off the bat:

The new HD 660 S lets you enjoy sophisticated audiophile sound in even more listening situations. The successor of the legendary HD 650 excels with the improved performance of its new transducer design. Thanks to its lower impedance, it delivers reference-class sound also when connected to hi-res mobile players, thus offering much greater versatility.

A) The HD 660 S is only a dB or two more voltage efficient, so there's only a modest difference in volume from a phone. On its product page, Sennheiser claims 104dB/Volt for the HD 660 S; in its manual, Sennheiser say the HD 650 has 103dB/Volt sensitivity. Higher-end portable players will all have plenty of voltage to drive a 600/650 to loud levels.

2) If you're going to tout a product as being more useful in portable applications you should include a short cable in the mix. Both included cables are far too large for that sort of thing; neither are terminated in a 3.5mm plug—for the moment at least, still the most common connector on portable devices. Add the 1/4" to 3.5mm short cable adapter and you have a fairly clumsy connection to portable devices.

I've also seen a post where a Head-Fi made an inquiry to Sennheiser about whether the HD 600 or HD 650 would be discontinued. The Sennheiser representative said the HD 660 S will replace the HD 650 in the line-up, and the older model will be discontinued. I've personally always preferred the HD 600, but acknowledge the HD 650 has a lovely sound many might prefer.

I'm bummed.

Were it any other maker producing the HD 660 S I would have been quite impressed with how close they managed to get to the sound of the legendary HD 600/650. But from Sennheiser themselves producing it and with plans to discontinue the HD 650 I can only shake my head in disbelief.

I loath the race to lower headphone impedance in high-end headphones to make them more compatible with portable devices. My experience with the three beyerdynamic DT880 versions with varying impedance gives me the strong belief that higher impedance headphones will outperform lower impedance cans of the same design. Unfortunately I think this holds true with the new lower impedance HD 660 S.

The new Sennheiser HD 660 S lacks the legendary smooth resolve of the HD 600/650, preventing it from scaling well as upstream gear is improved—one of, if not the most, important characteristics of a great enthusiast headphone. If you're not getting improvements on money spent on electronics you're missing out on half the fun.

Yes, I'll give these headphones a soft recommendation...they remain a decent headphone—comfortable, stylish, and close to as good as an HD 600. Maybe the stealth black look and smartphone capable efficiency is enough to tip the balance for some. But I'll also steer buyers towards the HD 600—or Massdrop HD 6XX if it becomes available again—as the better sounding alternative.

Watch on YouTube.

Sennheiser U.S.A. home page and HD 660 S product page.
Head-Fi impressions thread, sponsored thread, and reviews. impressions thread and 600/650/660S analysis thread.

Sennheiser USA
1 Enterprise Dr.
Old Lyme, CT 06371
(860) 434 9190

donlin's picture

Very clear and honest. It’s refreshing to have a well known reviewer that doesn’t love everything. Sounds like there may be a rush to get the last 650’s.

Maybe's picture

The 660S is rather boring. I was excited at first but I got Sennheiser'ed.

Performance was to be expected given that the HD 700 and the HD 650 use transducers with almost identical TS parameters.
I'm sure if you were to stick an HD 599 driver inside a 650 it would sound similar aswell.

Used HD 580s for 150€ with new pads seem preferable.
However, I think I'll buy the 660S grills for my 650. Looks neat.
The closed HD 800 is next on the list. Then the new Baby Orpheus. And maybe they'll do something completely new in 10 years.

MikeC20's picture

I am a headphone enthusiast but I started with my obsession with High Fidelity home audio, the headphone to me is 100% based on trying to get the best sound possible while being the most convenient.

I still havent fallen in love with any bluetooth so I am fine dealing with the discomfort of cords, but I have been wanting the HD650 but with the inconvenience of needing an amp to really enjoy makes it something that I would never use as I would rather listen to my home audio if I have to be stationary.

My currenty heavy in use headphones are the se535, HD558, AKG 553 MKII and one of my favs the AKG K240 (what a high value headphone!).

My question is, is the 660S is a significant upgrade over the 558/598 headphones? If so I may have a must buy.

MikeC20's picture

Great job as always Tyll, thank you for doing such great work over the years!

metal571's picture

Actually any of the 600, 650, and 660S would be an upgrade over the 558/598 series. The only thing you will lose is soundstage width, and also the signatures are a bit less bright and aggressive in the upper mids and treble region. Detail however is significantly improved vs the 5x8 stuff.

jaredjcrandall84's picture

Based upon reviews, yes it is, but apparently the 650 is better than the 660s, so go there instead.

metal571's picture

Did you buy brand new pads for your 600 and 650 units immediately before doing this review? If not, that has enormously colored your perception of these models' sound signatures. It is well known that older pads will give your 600 and 650 that "smoother" and more "organic" sound that you mentioned. As soon as the pads are replaced, the sound is significantly changed. I would like to hear full follow-up impressions and see measurements of all of these 3 units once you have replaced all pads, if that was not done already, for the sake of everyone who is going to buy pairs of these headphones brand new.

ericw's picture

Agreed. Rin Choi measured a HD 650 with old and new pads, and switching from old to new pads increased 5-6kHz by more than 5dB, and generally everything above 1kHz got tilted up.

see: (scroll down to "Discussion")

I'm not sure if those measurements have been repeated elsewhere?

metal571's picture

Solderdude also looked into this a bit, talking about older style 650 pads vs newer ones, in addition to pad condition.

crazywipe2's picture

All the Headphones Tyll uses for comparison are in almost brand new condition. He is more than 25 years working with headphones giving a huge contribute to all the Headphone World. Do you really think he messed up the review because of the pads? Man, this is ridiculous and disrespecful, you are not talking with a noob.

Tyll Hertsens's picture
The 600/650 I use are relatively new, maybe 4-5 years old. You have to remember I only use them for comparative purposes, so I would guess both pair have less than 40 hours on them. The pads appear in very good shape.
zobel's picture

grainy A moderate texturing of reproduced sound. The sonic equivalent of grain in a photograph. Coarser than dry but finer than gritty.

What causes a transducer to produce grain?

amartignano's picture

Although I don't ear this increased graininess when comparing my 660S to my 600 (indeed I ear the 660S to sound more "organic") I really appreciated this sincere review, as always.

gibtg's picture

Pads, schmads ... There's clearly evidence in the measurements that the treble responses differ from the past designs and I'd trust Tyll's ears to determine how those changes will effect the overall presentation of the headphone. That's why I'm here!

Excellent review once again Tyll!

pete111's picture

"But I'll also steer buyers towards the HD 600—or Massdrop HD 6XX if it becomes available again—as the better sounding alternative."
Letting people know that the 6xx are indeed available on Massdrop now, yes with a delay, but still... a 650 for 200 bucks...

zobel's picture

Is there a relationship here, really?
Aren't the factors that determine impedance in dynamic drivers
1) length of voice coil wire (L)
2) gauge of voice coil wire (AWG)
3) type of conductor in VC wire (what metal)
4) strength of magnetic field in VC gap (B)
5) acoustic and mechanical resonance (Ir)
6) acoustic and mechanical impedance (Imm)
7) voice coil geometry (underhung vs overhung)

Knowing of several examples of sound being improved by increased
sensitivity / lower impedances, rather than the opposite, I don't believe that design criteria (Sensitivity / impedance) is a determining factor in driver performance. Think, for one example, Sennheiser Amperior vs HD 25 II, even in aluminum for both. Requiring a separate special amplifier is becoming less and less popular.

Not to say that better amplifiers won't improve the sound of headphones, any headphones, sensitive or not. Not only are we moving away from chip amps in phones through a wire to the cans, but now it is the rage to be wireless, which involves inevitable signal degeneration. Compressed, lossy music files via Bluetooth to sensitive IC powered cans is the future, very sadly. It isn't the sensitivity of the cans that is the problem though.

Pdxsnap's picture

The introduction of this model does seem a bit odd. It could/should have been a slam dunk in just improving a little on a classic to build on its cult following. If they had just made a unit just appreciably bettter than the 600/650 there would be a large market in devoted followers in upgrading.
I wonder how much of the desire to drop impedance is the reason for the miss fire? I also wonder if there were heated debates within Sennheiser regarding the impedance and direction of this model. Time will ‘perhaps’ tell.

zobel's picture

For many of the reasons Tyll pointed to,these cans don't really cut the mustard anymore. None of them. Biggest problem...bass rolloff. Next to that, the veil..lacking low treble and high mids.

This is a failed attempt to address the real problems with these cans. I disagree that the Sennheiser HD 6XX Massdrop was such a deal. Personally I think AKG had a better can through Massdrop with the AKG K 7XX.

The fact that the housing of the drivers makes such a huge difference in sound points to how much differently we hear them with our various sized ears. I bet I fill a whole lot more of the cans cavity with my flappers than most do. The size,and shape of ear canals makes huge differences as well as hair, glasses (sometimes), head size (fit) it isn't too surprising that pairing drivers to the entire enclosure involved (cans and the individual wearing them) is critical and accounts for the varied responses from individual to individual.

Good review Tyll....very disappointing that after what, 17 years? Sennheiser hasn't made more progress.

potterpastor's picture

I consider the He-1 progress

pete111's picture

I have to say that after your comment I was quite surprised to look at the AKG's 7xx frequency response... AKG are not exactly known for their deep bass. I agree with you that this roll off at 100 is kinda... Well there's something missing. What I was gonna say tough is that to get this bass, in a sub 500$ range, you have to either go closed, or planar, with the compromise associated with both these design and to me the 6XX is still very good value. But I was just thinking today that... Yeah, great classic, very good sound but I keep coming back to something with subs. My other cans are He-400is and Th-X00, which are both to me better than a 6 serie senn. but still more than twice the price of a Massdrop 6XX

zobel's picture

That Massdrop version of AKG's 7XX has improved bass over previous versions..another good result for Massdrop. It measures down 5 dB at about 17 Hz...not too shabby at all. It has all the clarity and detail, if not a tad extra presence, which is from 3.5 kHz to 6 kHz, (not as Tyll has it) that is sorely lacking in the HD 6XX series.

For example the HD 600 are down 5 dB at 40 Hz,(17 Hz for AKG) and down 10 dB at 5 kHz, compared to the AKGs which are flat at 5 kHz. It adds up to much better bass, and even better detail and presence. $200.00...a great deal.

I haven't heard the HiFiman,HE 400, but it sure measures well! The AKG looks has much more similarities to it than the Senns.

Your Fostex TH-X100 and the AKG K 7XX also measure remarkably similarly, with the Fostex looking a bit better in the sub bass, and
slightly recessed in the highs than HE 400, and the AKG K 7XX. I imagine they all three represent better values than the Sennheisers 6XX series.

I'm guessing that Tyll never listens with a subwoofer, just his little Harbeths, which roll off like the Sennheisers, so it is understandable that he doesn't miss the bottom octave as much as people with flat systems. I design and build loudspeakers, and have been now for 27 years (seriously...with good measuring tools) and am spoiled by having flat in room response. Which do you prefer your HiFiman or Fostex?

pete111's picture

Thanks, I like them both. I really like the punchy and dynamic sound of the Fostex, definitely have more slam but the Hifiman 400is could be called more neutral and with a larger image. Objectively I think the Hifiman is the better headphone but (even tough hifiman marketing suggest that) they are hard to drive and need a decent amp... Nothing fancy but just something better than the output of a phone. I'm having great result with the Bluewave Get that I've designed and put to market... I know, probably deserve to be flagged for self promotion... but threw it in anyway, I'll take the blame if need be...

Phoniac's picture


amartignano's picture

No progress? You forgot hd800.

amartignano's picture

Moreover many find the hd660s an improvement over 600 and 650.

roscoeiii's picture

I think Tyll makes it quite clear the specific reason he prefers the 650, 6XX, or 600. Of course the relative importance of various aspects of audio gear differs from person to person (for example, soundstage isn't especially crucial to my audio decisions). It is very easy to imagine someone preferring the 660S based on aspects of it compared to the 650/6XX/600 that this review describes.

I very much appreciate how Tyll contextualizes his own personal preferences in his reviews. And in many cases will not review a pair of headphones (bright/treble heavy) that go against those preferences. Sometimes we gravitate towards reviewers whose taste in gear reflects our own. In other cases, we must triangulate our tastes with the reviewer's and hope that the review has enough detailed description to allow us to do that.

I hope that in the comments those who prefer the 660S also extend us the favor of giving their reasons why. Let's not forget the role that personal preferences play in this hobby.

amartignano's picture

I want to specify that I really appreciate Tyll reviews and opinions even when my sensation are different. I wrote a long post about my impressions on the 660S on headfi, and I will not repeat here :p It's not my preferred headphone, I like my hd800S more, and I might also prefer my hd700 on the hd660S. Nevertheless I like the 660S and this time I disagree not only in the preferences (obvious because we are all different) but also in some audio facts, which is strange as I always agree with Tyll on the "facts". For example, like others I find the hd660S to have less grain than the hd600, not more.

amartignano's picture

More specifically, there's a thing of the hd660S that really mesmerized me, that it's not mentioned in the Innerfi's review. It's the wonderful work on timbre and harmonics of cymbals and triangles that the hd660S does. It really surprised me. The hd600 in direct comparison seemed quite "muted" on high cymbals and triangles.

BoyBalastog's picture

I generally assume that because Tyll tends to dislike strong treble that he percieves a hard edge on the upper frequencies as being grainy because of how harsh it sounds to him, rather than because there's any actual obscurity of detail. I get what he means when he says that being detailed and resolving isn't the same as merely having elevated upper mid and treble response, but his own preference towards smooth resolve over bright resolve is evident. Some people, including me, prefer to have actual presence of detail while having a bright edge to the upper frequencies to accentuate it.

But on the other hand, I once did hear an HD700 and I really did hear a grainy fuzz to it, but in a way that was markedly different from the very veiled (to me at least) HD650. I've only tried it once admittedly, but it left a bad impression. So I'm not all too surprised that Sennheiser may have fumbled a bit in trying to stuff the HD700's drivers into a 600 series shell to try and make for a lower impedance model.

Phoniac's picture


Phoniac's picture

I did not post this here - the buggy software did...

potterpastor's picture

Appreciated the heartfelt review.
Hopefully in years to come, some of that HE-1 awesomeness will trickle down to the 600/700 series.

I really enjoy the HD 579, the older brother of the 569

MattTCG's picture

I agree with some of your review but there are some issues that we are quite far apart on. Just want to say that its a mistake to suggest bending the headband in the middle. You'll have a contingent of hobbyist emailing you after the headband assembly snaps in two. ONLY stretch the metal section...imo.

amartignano's picture


Tyll Hertsens's picture
Sennheiser has a GREAT materials science lab. I've been relieving the pressure of these headphone in the way I described for...what, 20 years. Never oncehave they felt like they were getting anywhere near fracturing or even fatiguing the material. Don't ham-fist it for sure; feel what's going on. But bending the metal headband extensions will change their shape, and that shape is designed for that pocket in the headband.
GNagus's picture

Senn is replacing a headphone for an new and "improved" version instead of complimenting the HD650 with an easier to drive version. I have some theories why:

1) The HD650 isn't selling as well as Sennheiser would like, when there is the 600 selling for less (MSRP prices).

2) The HD700 is not selling well and Sennheiser created a new headphone using HD700 parts from the parts bin (driver, etc)

I'm disappointed, but only that the HD650 will be discontinued.

darkswordsman17's picture

The pad differences could be interesting. Actually, Tyll did you try swapping the 660 pads with 650/600 ones to see if that alone might offer the subtle sound differences, or even just a change?

Another thing that would've been interesting, and granted them not including a 3.5mm cable seems to indicate they don't expect it in spite of their reasoning of making it more efficient, but a comparison out of portable players I think would be fairly important. The thing is, I'd almost guess that they'd actually be worse (with regards to smoothness), but perhaps that's the desire, or the bass blooms up more which is what more people would want. Or maybe after processing that might be typical on such devices, that the treble is enjoyed (basically it helps retrieve some of that lost that causes say the HD650 to sound too veiled)?

zobel's picture

Summary Table
Frequency Range Frequency Values
Sub-bass 20 to 60 Hz
Bass 60 to 250 Hz
Low midrange 250 to 500 Hz
Midrange 500 Hz to 2 kHz
Upper midrange 2 to 4 kHz
Presence 4 to 6 kHz
Brilliance 6 to 20 kHz

zobel's picture

...many,if not most, would call upper midrange (2 to 4 kHz ) low treble, with treble being 4 kHz to 6 kHz...presence and air (or brilliance) from 6 kHz up.

I think we should all use the same (or close) definitions for what we are talking about, otherwise it is just babble.

sszorin's picture

@ zobel - Sub-Bass is 15/20 to 40Hz.
150 Hz and up are lower middle frequencies

zobel's picture
zobel's picture

Sub bass...............1o Hz to 25 Hz
Low Bass...............25 Hz to 50 Hz
Mid Bass...............50 Hz to 100 Hz
Upper Bass............100 Hz to 250 Hz
Low Mids..............250 Hz to 500 Hz
Midrange.............500 Hz to 2000 Hz
Low treble..........2000 Hz to 4000 Hz..(with presence 3kHz - 6 kHz)
Treble............4000 Hz to 10,000 Hz
Upper treble....10,000 Hz to 20,000 Hz..(same as air or brilliance)

Tyll Hertsens's picture

I go with the mothership. John Atkinson has all the ranges buried in the glossary here:

I think the human vocal range as a stand-in for where the mid-range is. For me, 150Hz to around 800-1000Hz. after that, overtones, spittle throat sounds, and consonant/sibilant sounds appear, which I think of as in the treble area.

The character of 'presence' occurs, in my opinion, in how well one can hear these upper glotteral and consonant making frequencies. Essentially, twig and branch snapping stuff. These sounds---maybe 800Hz-4kHz---are where our primal survival system triggers reside.

Emphasis will give you presence; de-emphasis will give you distance---muting through the trees, I'll offer. I consider that treble response.

I see it as:

Bass: 15Hz-150Hz
Mids: 150 Hz-1500Hz
Treble: 1500Hz-20kHz (That third of an octave up there don't hardly count.)

zobel's picture

I think that it will work for all practical purposes..even if not quite the norm, I think, from most of what I've seen elsewhere.

I think the presence range has almost always been listed no lower than 2kHz, and extending to 6kHz (usually), and maybe the reason for that is because those frequencies are above the fundamentals in music far enough to change the distance perceived to them more than simply the quantity of them. Think a distant branch snap, or grass rustling vs a close by one. Low frequencies travel much further than higher ones. We may hear loud rustling or snapping, but our distance cues are frequency based. When using EQ for playback or recording instruments...including the voice, the cues to distance are found in the low treble..3kHz to 6kHz. You can prove this to yourself by playing with the EQ in listening sessions. If upper mids (800 Hz to 2kHz) are raised in level, to most, I think, it only makes those tones louder, not closer. It is all subjective, of course, but this is one area where there is disagreement. No matter, really, if we are all on the same page.

Long time listener's picture

I agree that this looks right:

Sub bass...............1o Hz to 25 Hz
Low Bass...............25 Hz to 50 Hz
Mid Bass...............50 Hz to 100 Hz
Upper Bass............100 Hz to 250 Hz
Low Mids..............250 Hz to 500 Hz
Midrange.............500 Hz to 2000 Hz
Low treble..........2000 Hz to 4000 Hz..(with presence 3kHz - 6 kHz)
Treble............4000 Hz to 10,000 Hz
Upper treble....10,000 Hz to 20,000 Hz..(same as air or brilliance)

Someone on this site once defined "midrange" based on the frequency of middle C on the piano--failing to note that the piano is only a bass/midrange instrument. The keyboard does not present the full range of frequencies shown in Tyll's graphs, but only extends into the upper midrange or lower treble. Thus at about 256 or 260 Hz, middle C actually represents the transition from upper bass to lower mids--as shown in the post by Zobel.

Tyll, the presence region is roughly 2khz to 5khz. It's not for you to re-define according to your own predilections.

I'll be very happy if the above can be used as a reference.

zobel's picture

Bass.........20 Hz to 250 Hz
Midrange....250 Hz to 2500 Hz
Treble......2500 Hz to 20,000 Hz

This represents the range of Human hearing, and divides the frequencies into the old standards of Bass, Mids, & Treble. These have been the widely accepted definitions for many years.

In the table below, the further subdivisions are useful to more accurately describe the audible spectrum, which have developed over time, to describe the ten octaves we can hear as illustrated below. Note also the frequencies that most refer to as ("presence") and ("air" or "sparkle"). It is important that we use these standards in naming the different bands of frequencies in order to have a common language. If not referring to this standard, the only alternative is to talk in terms of the frequencies in Hz, and mention only the numbers.

Sub Bass...........10 Hz to 25 Hz
Low bass...........25 Hz to 50 Hz
Mid Bass...........50 Hz to 125 Hz
Upper Bass........125 Hz to 250 Hz
Low Mids..........250 Hz to 500 Hz
Central Mids......5oo Hz to 1000 Hz
Upper Mids.......1000 Hz to 2500 Hz
Low Treble.......2500 Hz to 4500 Hz ....('presence region'.....
Central Treble...4500 Hz to 10,000 Hz ...3 kHz to 6 kHz)
Upper Treble...10,000 Hz to 20,000 Hz .('air/sparkle' 10 kHz & up)

amartignano's picture

Anyway, I find the absence of listened music for the review a strong defect on this and other reviews (excellent for all other things). I almost never found an headphone always better than another with different recordings.

Phoniac's picture

You first said it correctly in your review, but then come up with thgis wring statement again:

No, the 660s is far from being loud enough on a usual smartphone like an iPhone.

Phoniac's picture

Ok, I give up. This software just too stupid.

coastman25's picture

Thank you Tyll for yet another exemplary review. Being late to the party has its rewards. You are able to comment on the rumours and previous badly made reviews.
I can only assume other reviewers of these phones took too much notice of the Sennheiser hype and swallowed it.
These phones seem to have been designed and made via a committee, with the marketing and sales departments having the biggest say. At best, they are an attempt to be all things to all people and failing to build on the HD 600 heritage. It is as if they do not know the value of what they already possess.
Hats off to you Tyll, for being so exacting and honest with your evaluation.

amartignano's picture

Have you ever heard the 660S? I ask because I have them, and I'm entitled to partially disagree with Tyll impressions. I really appreciate his opinions, but it's not the only "truth" in HiFi. The fact that he disagrees with others, doesn't mean that the others are dumb hypey fanboys.

coastman25's picture

Have you ever bought a fake product? The more you pay for it the less likely you are to question its authenticity. I think its called self justification. If you are happy with the HD 660s then I guess that's all that matters.
Happy listening.

amartignano's picture

Ok, you never heard the 660S.

coastman25's picture

My comments were about the quality of the review and the reviewer not the product. For that I don't need to hear the 660s. I trust the reviewers integrity he didn't just comment about the sound he went into detail about how Sennheiser's misleading hype, the drivers, how they measure like the 700's etc etc.
I have bought 3 headphones without first hearing them, just going by Tyll's reviews and I am not disappointed or have found myself disagreeing with his reviews.

amartignano's picture

The fact is, that many headphones enthusiast, me included, find the HD660S perfectly good as an hair of the hd580/6xx heritage. This is respectable like other opinions. And I strongly disagree with your assumptions about 660S creation and judgement about who likes this headphone. Here we say that you "did a lick"... but you never heard the headphone. To be clear: I always appreciate the quality of Tyll reviews, except for the absence of indications of the music played for the review.

coastman25's picture

So why don't you take up your complaints with the author of the review? I cannot help you. I am happy with the review your not.

amartignano's picture

I was mainly commenting about your post, so I wrote to you. Why write to Tyll about your post? :D

coastman25's picture

Well if you cannot read I guess there is no point in commenting at all!

amartignano's picture

And I've also bought headphones despite Innerfidelity reviews and liked them very much with my ears/tastes.

IgorC's picture

Interesting review. Thanks!

My first thought was that 660s had hand-picked 650s drivers (with better THD and FR characteristic.)

Well, it's actually HD 700 driver after all. Makes sense. Probably Sennheiser doesn't want to throw away some HD 700 drivers which don't meet THD requisites (<0.03%) but still suitable for HD660s (<0.04%)

I still remeber that my first audiophile grade headphones were HD 650. :) Awesome.

Impulse's picture

Welp, that settles it, I'd been curious about these for a little while but seeing as I have some decent upstream gear I guess I'll pass.

I've been wanting to hear the difference between the HD650 & my HD600, and/or mod the former while having a sort of reference, guess the time to do so is now before they vanish.

Hopefully they're still $300-ish in January after I'm done traveling for the holidays...

GimmeCans's picture

I want to echo the sentiment expressed by an earlier commenter, that it's good to know that Innerfi is willing to call things the way you see (hear) them, even when it doesn't 'tickle'. Manufacturers shouldn't expect a 'free ride'.

As a longtime HD650 owner and advocate, the review eased the tinge of buyer's remorse I felt when learning of the 660S just after buying the Beyer Amiron which is $100 more. Despite my high regard for Senn's classic, I'd be hard pressed to name an area where the Amiron doesn't outperform the 650 to my ears (maybe the 650's smoothness makes it a little more 'forgiving' on some material.) For those who were considering the now-discontinued 650 or another open can in that range, the Amiron should be on your radar IMO although I will admit the overall signatures are quite different.

GumbyDammit223's picture

Do you want a HD700 to compare against? I'm in Bozo so it would be quick to let you borrow mine.

GimmeCans's picture

Now comes the HD58xx from Massdrop, looking almost identical to the HD6xx. There's only one man who can sort all this out.... Look! Up in the air! It's a bird! It's a plane!

GimmeCans's picture

Oh, and it's $149....

Martin.'s picture

Saw this as well yesterday. Seems very interesting, would like to see someone review it. I also have just bought a 6xx from Massdrop cause of this review.

arteom's picture

Great review. I get the impression that manufacturers are designing their products to play well with low level gear like smartphones. Think they have come a long way with pulling that off while still having a sound that is above consumer level products and more in line with audiophile level. The compromise being how well they scale and the grain you spoke of. I think they are working hard to disguise the grain as 'energy up top'. It is remarkable that they have been able to achieve this at all, don't think we would have seen a product like this ten years ago. That all being said, I won't be trading in my 650 anytime soon.

verbosity's picture

Hy Tyll,

Would you say the 660s is superior to the HD600/650 when driven by a cheap <$300 amp? If so it seems an easy explanation for its existence and positive reception in the forums. If not, who knows... maybe just personal preference of most people deviates from your own in this case?

Michael Ford's picture

Thanks, Tyll. Great review as always. You've given me all the excuse that I need, and have been looking for a long time, to buy another HD650! I'll use one with a CH650S balanced cable on my HDVD800, and the other with the stock cable on everything else. I also have an early HD600 (and 580 Precision) and although I fully understand why you and many others prefer the HD600, my preference is for the HD650. To me it is warmer, and yes, darker, but it has better resolution and soundstage.

One thing I'm certain about is that if Senn do discontinue the HD650, it will immediately go from legendary status to cult status!

ScaryFatKidGT's picture

I think Sennheiser is running into the Gibson/Fender problem... they have been doing things so right for so long either by nailing it right away or through trial and research an actually being great or by customers just expecting that sound or a combination of the two that if they make anything different it doesn't do well. I think Sennheiser should have improved the HD700 with an "HD700 S" instead of making a 660 and then the Massdrop "580" which is more of a 660 in 580 skin.

detlev24's picture

Another quick review with comparison to the elder models; from another point of view. Enjoy!

blogkens's picture

These headphones are really very great.

blogkens's picture

if Senn do discontinue the HD650, it will immediately go from legendary status to cult status! Read more.

Michael Ford's picture

Tyll, for your information, I've just replaced the ear pads on my original (pre Jubilee model) precision 580's with replacement Sennheiser pads (part number 050635), and they are identical to the new pads on the 660 S, i.e. a little thicker and slightly bevelled on the inside. This leads me to assume that all 600 series headphones will now come with pads like this, and it's not a difference specific to the new 660 S.

Best regards, Michael.

Michael Ford's picture

I now see that the Senn rep stated (in the Headfi post that you linked) that the replacement parts would be the new design from now on, but, again, one would assume that means that new HD 600 and HD 650 headphones will also have the new pads. It wouldn't make any sense to manufacture two slightly different shape pads and provide the old type only on new HD 600/650's and not as replacements for those headphones. All pretty irrelevant in the bigger scheme of things, but nonetheless, good to know.....maybe......

poekimalu's picture

Hi, I have LCD2 Classic which I love it, but it gave me a headache most of the time because the weight and clamped to much near my ear. My question is should I get HD660S or HD650 if I decides to swap my LCD2 Classic? I did tried HD660S before but never try HD650. Cheers

smileday's picture

Could you check whether the isolation graph correct? 4-5 db isolation across the audio band from an open back headphone? HD600 and HD650 did not do that.

Luigi's picture

Sennheiser started to sell the 660 with the 58x name on massdrop. The difference between the two models are 350 dollars and a 10 cent of felt againist the back of the driver...