The soon-to-be-controversial HD 660S2 thread

I'm new here so I'm going to chip in my two-penneth in a more restrained fashion than I'm used to for fear of getting into trouble. I'm tagged as a MOT so I'm not 100% sure if I'm allowed to say this, but here's my take on the 660S2.

I have a 30 year career behind me in engineering (nuclear, aerospace, hi-tech) and in that time I've touched on product development both in industrial realms as well as small-volume and mass-produced consumer products, so I like to think I have at least some insights as to how the whole product management and marketing circus works.
The product development cycle is complex and interesting and obviously varies from company to company, product to product etc. but there are common denominators and commonality in many areas, not least of which is 'product residual longevity'.
Essentially, in its' broadest terms and without wanting to sound like I'm lecturing this basically defines as how any given company can milk a product until it's dead! How many revised, refreshed, regurgitated, renewed variations and iterations they can pump out until people stop buying it etc. I think Sennheiser's 660S2 is one such example.

Sennheiser have a key/golden product (HD600/650) which has been massively popular for them for many years and has been revived or rejuvenated and has subsequently spawned offshoot products in the form of the massdrop 6XX, 660 which have also been massively popular and very profitable for them.
So where do they go now in terms of the product lifecycle? Why, another slight variation on a theme but this time with a hiked margin of course. 'We know people will buy our products, so let's charge more. Then when we bring another revision out we can probably charge exponentially more again! Win, win!'

That sounds very cynical, but it actually makes a lot of commercial sense and many large consumer product organisations are benefitting from doing exactly the same and it's actually considered to be an industry-standard. Just consider the price of an iPhone these days as another clear example. Ludicrous! Is it as groundbreaking as it was when the original iPhone came out? No. Does it do anything massively better than a TOTL Android phone or the model that preceded it? Not really. So why is it hugely more expensive? Because people will buy it. Because Apple has an assured market. People will buy it without question or consideration. It forms part of brand loyalty and brand loyalty is what the product management and marketing departments of mass consumer product companies protect and nurture and invest in the most.

And that's the crux of my theory. Sennheiser has an assured market where it has already probably exceeded a minimum profitability target by flogging this old horse in new shoes. Because it can do so very successfully. I'm personally really curious as to how they will regurgitate the next revision and how long they will go on milking it for...

Someone earlier mentioned that you can still find 2nd hand HD650's and 600's in great condition and afaiac that's where the smart money should go. They're classics and still stand up against vastly more expensive headphones in terms of resolution, clarity, staging, comfort, build quality, etc etc.
But, and here's my risky curveball left-field claim; the even-smarter money will buy a 2nd hand HD565 set!
The HD565 is one of the most underrated headphones on the planet in my opinion. As a 'Made in Ireland' period fanboy I'm intimately aquainted with the sound signatures of all the HD5* and HD6* models up to the 650.
I've spent time with borrowed HD6XX and 660's and frankly wasn't impressed. I thought: 'ok a slightly different tune. Not 600, not 650, not even something inbetween, just a different tune with shades and inferences from both but a Sennheiser 'pastiche' SS.' That was my conclusion.
The HD565 however, is amazing, fun, resolving, and if you're prepared to put the effort in it EQ's to within a hair of a stock HD650 sound signature. No really!

Well, in any case, before you drop any coin on any future HD6** model give the lowly but worthwhile HD565 some consideration! If you can find a set that is. They're out there. Lurking, unloved and neglected, like a pair of old underpants in cupboards and drawers accross the planet

Do I now need to go and sit in the naughty corner for that rant?



HD565's on the left. Ok, ok they don't look as good. Especially with those dumb woollen headband things attached to them but they're actually a LOT more comfortable than the HD600/650!

 

If Sennheiser would make the HD250 II Linears again instead of HD700-monstrosities I would run to their store. That is not a joke. Some of the older Sennheisers are audio gems.

Either way my HD600 is staying.

I cannot justify the HD660 to myself. Maybe it is the Sennheiser for noobs. In that case it is not the worst headphone, just very expensive.

 

I have bought into the Senn mystique for the EIGHTH time. I have written off the Sennheiser's sound as not being my cup of tea. Way too neutral for me.

So, the HD660S2 comes out and folks are saying, "But it finally has bass!".
I am skeptical and they are expensive for an HD6X headphone. I have been tracking a used set online (CAM) and I came into some money on Monday so I bit. I got them today and put them on the Valhalla 2. Nice sound, but I was not overwhelmed. And where was this supposed bass boost at?

After I bit I went to my test list and was like mmm...
Then I switched to the iFi Pro iCAN and set the bass boost to the mid setting. Wow! They will never be bass head 'phones, but I am liking them Much more. This weekend will be all this combo.

For context my favourite sound signature is the Focal Elex's and Clear's. Tonight I am going through old rock and new rock, while drinking rum and Coke. I imagine tomorrow will be a lot of jazz.

My initial run of Sennheiser's was; HD598C's, HD58X's, HD600's (twice), HD6XX's (twice) and HD660S's. I kind of regretted selling my HD660's as they filled a niche in my collection. But I just never loved them.

While I am reluctant to use my Schiit Loki, I am quick to pull out iFi bass boost on any headphone, except the bassiest. (Think CFA Cascades and iBasso SR2's).

I am Really looking forward to the weekend with this combo.

 

I think this is where your expectations could have been met better, with the model that you missed out from that lineup - the HD650.
I always describe the 650 as being a '600 with a bass kick'.
I'm pretty sure you would probably also like the lowly, ancient HD565 if you're into adding EQ as you can tune them to within a whisker of the 650.

 

Are the HD650's really that different from the HD6XX's?

 

In my opinion they are all individually tuned and have their own SS.
There are definitely crossover characteristics between some HD6** models. I wouldn't actually call it a Sennheiser 'house sound' in the same vein as Audeze for example, but there is definitely commonality between the models.
After spending time with the 6XX I would say they were closer to the 650 than the 600 in terms of crossover characteristics but there are still aspects that distinguish them.
However, you only really notice the differences in character when you A-B them. Sometimes I've grabbed by HD565-600 Frankenheisers thinking they were my HD565-650's only to find myself yearning for a bit more bass oomph...then realising I chose the wrong pair. (I fitted them with a grey and a black headband to tell them apart.)


To give another example of how subtle, or in this case- not so subtle the characteristics are between even the same Sennheiser models I just finished refurbishing my 2nd pair of HD545's. I wanted to get a 2nd pair in order to compare them with my existing pair which sound absolutely lamentable, even when A-B'ing with the lower positioned HD525 and HD535.
The 2nd pair of HD545's sounds totally different to the 1st pair of HD545's and I can only put this down to either a deterioration of the drivers in the first pair, but now that I have compared both sets the 2nd pair has clarified their logical position within the HD5** line-up.
I'm assuming this is ultimately down to the slight variations in the materials used for the paper baffles and polymer film of the drivers at different stages of the production run and/or un-declared revisions of the same model.
Swings and roundabouts!

 

I am enjoying them today with my jazz. Using my iFi amp with a touch of bass boost and am getting a nice full range sound.
In hindsight, I suppose I knew that these were not going to my hard hitting rock 'phones.
But hopefully they find their own niche in my collection.

 

Well, I am nine days in. They are clean and clear. The soundstage is a bit small and the bass is a bit light. They sound good with most everything, but especially jazz.

Today was a whole afternoon with Lee Morgan and they were great. They are getting more comfortable every day.

They are good with all the amps, but I do prefer the iFi amp w/minimal bass boost.

They are Super easy to power, compared to what I expected. I am a quiet listener and I can't any of my amps out of low gain and the volume is only at 9:00-10:00.

Have to take a break tomorrow and enter the world of dongles.

 

Well, I just finished almost a week with my S2's. I have to say that I am really warming up to these. Most surprisingly, I find that the bass is pretty damn good. Not like the Focal's, but they hold their own.

Another surprise was some amp pairings. I was going down memory lane for a few days with 60's and 70's pop, with a few from the late 50's. On my favourite amps (iFi Pro iCAN and Vio 220), the music was a bit "noisy". You could certainly hear all the flaws and it was a little annoying. I then switched over to a Little Dot MK9 and Man, was it awesome. It covered all the flaws with wonderful tubey goo. I then switched over to the Valhalla 2, which I find more crisp and clean, but it was pretty awesome too.
For the old stuff at least, I seem to prefer the tube amps. I have never preferred a tube amp on any headphones over my top two. I guess it just depends on the situation.

Also, I figure the higher end amps would just amplify any flaws in the recording or the copy that I have. Although all my jazz, mostly mid 50's to early 70's sounds great with these and ANY amp.

Bottom line is that I think I have finally met a Sennheiser that I will keep.

 

Hard to believe it's been 6 months since the 660 S2 were released. They're more than burned in and well loved by now, and I think they are indeed a more well-rounded proposition than the 650. The bass is just more natural and the veil is not there (as much).

Folks considering these (still) may prove to be wiser than I was -- paying retail was a splurge. They can now be had for 449.95.

 

Can anyone compare them to the more bassy HD58X?

 

Well I am several months into ownership and decided to make a small change. I pulled out the foam 0ads and tried them "naked". It was awesome, to me.

Today I pulled out the foam pads and replaced them with panty hose to protect the drivers. I much prefer the added clarity.
This is how my S2's will roll from now on.
Unless I change my mind.

 

Given these are closer to USD900 in some parts of the world (cough) yeah no that's genuinely disappointing.

So other than the FR differences which I think everyone and their grandmothers have been harping on about, how does the HD660S2 fare for the like of imaging clarity, front to back layering, @purr1n? I feel like relative to a lot of other headphones the HD600 and HD650 actually do a great job with layering (when not plugged into insipid gear), just that their staging is relatively upfront, so hopefully these at least match it on that front?

IIRC this is the HD700 driver, so while it might be suckier for microdynamics (please don't tell me it's hypersharpened and truncated like the Klipsch HP-3) does it at least do the macrostuff well, doesn't get congested with super busy passages like Radiohead - Burn the Witch? On that note, how much do they scale going from Apple dongle > Modi/Magni > WTF stack?

Definitely curious to see burst decays and other measurements when you have the time!

P.S.
Is the dynamic range on this good for classical at least?

 

Dirty first impressions, will try them on my reference system soon, just trying to get something out there for now.

Disclaimers: I listen for pleasure, don't pay attention to measurements, and entirely rely on my ears:

Listening notes:
Using Supernaut and Tubadour 3SE:

JAR600V2 has a natural flow to it that the 660S2 can't touch.

Not grainy at all like the OG 660 is.

Doesn't out-resolve the 600/650.

Bass is more present here than 600/650.

Vocals are far more present and resolved on JAR650V1 - 660S2 loses in this department. In general I'm getting an overall better presentation in exchange for better bass thump that the 660S2 provides.

Side note, BP650 which I love in isolation just are no match for JAR650V1 (SS).

Bit of a blanket over the 660S2 which some could find favorable but I'm into the air and space around instruments and the blanket kills that. So hearing the venue is harder on live tracks recorded in larger venues.

There's some muffling in the female vocal range. Makes the sound a little congested instead of being open. Bringing it a bit out of focus.

Jar600 has way better separation.

660S2 is a 600 down low but a 650 up high.

Older Senns are more refined, 660S2 is more unrestrained, for better or worse.

JARBS600V2 smokes it in everything except impact.

There's more micro FOR SURE on the older headphones.

Morning edit: These are actually very enjoyable in isolation. It's only when directly comparing them to the various older Senns that I'm able to pick them apart. If I just put these on my head and listen, they're enjoyable and other than being a little hot in the treble they're very nice. If anyone doesn't own other Sennheisers and just wants a Senn without having to hunt down older discontinued or modified models, these are an easy grab.

 

Try pulling the foam filters out and see what you think. I am not a big fan of most Senn's, but I liked these more after pulling the filters.
But the true Senn fans don't seem to like this mod.

 

I am always grateful to be included on loaners so thank you to all who made it happen. I was on the OG 660 and JAR 660 loaner as well.

Gear: Pi2AES -> Yggdrasil GS or Yggdrasil MiB -> MJ3

The new 660s2 is a distinct improvement over the OG version. It still is not as resolving as my Kiss 650s. The 650s have more refined treble. I think the 660s2 is geared toward newer recordings - any additional clarity, air, or squarish-ness in the track helps the 660s2 sound more resolving and more open. However, I preferred the HD650 with almost all recordings. I like the airyness of the kiss 650 and the 660s2 was always a step behind here. For that reason, I preferred the Yggdrasil GS over the Yggdrasil MiB with the 660s2.

The HD650 sounds like it should be more expensive. The 660s2 sounds rougher and grainier to me.

KISS mods might open this headphone up a bit. On the other hand, the JAR660 sounded like a completely different headphone when compared to the 660s OG, so I don't know. One thing is for sure, the 660s2 is too expensive for me to buy one just to do a kiss mod. If I ever see a used one for sale for say $200 or less, I might scoop it up and give it a shot.

 

This loaner tour was an important one for me, while I'm sure it was kind of "meh" for others, as this was my first legitimate experience with any Sennheiser HD6~~ headphones. Aside from a brief 5 minutes spent with some HD6XX at a local meet one time, this has been the only first hand encounter with a pair.

Gear: Lenovo T14 (JRiver) / Pioneer Elite DV-47Ai > Schiit Bifrost 2/64 > DIY Pass ACP+ / La Figaro 339i(*)

(*) On loan from @mjames7

First Impressions
Opening up the box and knowing the retail price of these headphones, I was admittedly a bit surprised, as I thought the packaging would have been at least a little more robust. But, having experienced the Grado way of packaging $500+ headphones, I guess it wasn't that big of a departure. That said, they certainly felt cheaper in the hand than expected. More on this later, but the HD650's I picked up for comparison felt substantially more quality than the 660S2.

Initially, I only had my DIY Pass Labs ACP+ solid state headphone amp on hand to plug the 660S2 into (rated for 1W @ 32ohm). After everything I read, and some direct feedback I got here and elsewhere, I knew this low impedance amplifier was not going to pair well with the high impedance drivers of the 660S2. That was for sure confirmed within 2 minutes of listening. While I could get plenty of volume, the sound was thin, lifeless, flat, and utterly boring. There's nothing more to be said, and it was a good learning experience in the importance of component matching. Thank goodness for this forum and mjames7.

Pairing with the La Figaro 339i
After receiving a PM from mjames7 and learning he lived less than 10 minutes away from me, he very graciously offered to lend me his La Figaro 339i with some various tubes to play with. As an OTL design, I was able to get a proper experience with the HD660S2, and boy did I. Within the first 5 seconds of pressing play, my eyes lit up bigger than the tubes. Immediately I was aware of the warmth, dynamic drive, smooth treble response, and enveloping sound of the tubes paired with the Sennheisers. Honestly, the feeling was not dissimilar from my first time hearing a good car audio system. Like...THAT is what I've been missing?



Ok, with all of that out of the way, I'll sum up my thoughts on the HD660S2, which has already been captured really well by others in this impression thread, which rang true for me as well:

Positives: Dynamic, deep, quick and slammy bass response (improved considerably with tube rolling - initially was a bit more bloomy and bled into the midrange); gorgeous midrange with excellent vocal clarity, spaciousness around the vocals with very good depth and surrounding instrument separation; vivid center image with very accurate imaging capability, detailed treble response. Above all else, the tonal and timbral accuracies of the midrange give an overall sense of being natural. Voices sound so true to life - not a recording - but just real. I've been looking for that for a long time.

Negatives (more like not-to-preference): intimate soundstage (though not that bad), bright and sometimes sibilant treble, instrument separation within the soundstage was marred a bit at times (recording dependent, and this is mostly as compared to LCD-X). Listening fatigue did come into play after extended sessions, driven mostly by the treble response that had a more forward bite to it than I prefer.

Comparison with HD650
Given the enjoyment I had with the 660S2 paired with the 339i, I really wanted more time with this combination. So I hopped on Amazon and picked up a pair of new HD650's for $300 (btw, on Amazon the HD660S2 sells for $400 now). This gave me a pretty quick comparison between the two designs sonically, and I could very quickly tell the differences, while also confirming that my preferences absolutely align with the HD650 (though admittedly, missed some aspects of the 660S2).

As others report, the HD650's darker overall sonic signature helps smooth out and tone down the treble response. Gone is the forward crispy bite of the 660S2, but so is the deeper-reaching bass response, along with some more articulation and clarity in the bass. The soundstage is even more intimate as well, and instruments have even less room to breathe. However, the imaging capability seems to be essentially the same, so I don't feel like I'm losing much there. Even despite some of those lesser qualities, the HD650 simply draws me in with that midrange (I'm glad I can finally understand why these Sennheisers are considered such a gold standard in that regard).

Conclusive Thoughts
The single biggest element of praise I can give to the HD660S2 (and HD650), with proper amplification, is that I got completely lost in SO MUCH music for hours on end each day. I could not stop listening, and EVERYTHING sounded "wonderful". Technically, the LCD-X is capable of more and can drop the wow-factor with the right music, but the HD6~~ just does so much right. The thing that really struck me was just how much larger a range of music I was enjoying with them - including the lesser quality recordings that I always find myself peeling away from with the LCD-X. Sure, I get a lot more of the audiophile goodness when using the LCD-X, but for pure music listening enjoyment, I think I would turn to the HD6~~ with a great tube amp far more (if I owned them).

At this stage, I don't have the funds for a proper tube amp to complement the HD650, so I will be returning them shortly (along with the 339i). But the time I had with the 660S2 was a personal revelation period, and I'm truly grateful that I got to spend several days with them. For the current market price of $400, I do think the 660S2 is a GREAT option for anyone who is looking for the extra treble energy and dynamic capability in a HD6~~ headphone.

and now for some tube porn, because I'm addicted