[donlin]

Sonarworks mentioned once the most polupar headphones they get shipped for individual calibration is the HD650, so one could assume this headphone to be very popular for studio work. The HD600 is a bit on the bright side for my taste, my personal "neutral" would be the HD650, the HD660S I find leaning slightly towards "dark" and I find it very entertaining for music listening. The HD650 is a bit darker and also a bit brighter compared to the HD660S, depending on the frequency spectrum you look at.

For studio work I'd probably go for a HD650 and send it to Sonarworks for a calibration setting.

Headphone amps and DACs make quite some difference with these headphones, especially the HD650, which is more still more picky then the HD660S. All three scale very well. You can get lots of resolution out of any of these. They also sound very simillar to each other, I own all three and could basically live with any one.

Excellent analysis. I'd agree with all of this. It's really true that the HD650 is darker and brighter depending on frequency with the 660S seeming slightly darker overall. Could and have lived with all of them. There is something with this basic platform that even with different drivers, it just seems to work.

 

[Mike F]

FWIW there is very little mention of the HD660S on https://www.gearslutz.com/ which is a pro audio site. The HD600 and HD650 are so well established (for very good reasons) for pro use that the HD660S seems to have been overlooked, not least I think because of course the true successor to the HD650 chronology and technically was the HD800, which is also widely used. It’s hard to get pros to part with more money for the HD660S when it has already effectively been superseded and sounds so similar to a well established headphone which is considerably cheaper.
It’s also relevant here to point out that Sonarworks were not impressed by the HD660S, which is probably why they haven’t provided a calibration for it.

 

[G0rt]

FWIW there is very little mention of the HD660S on https://www.gearslutz.com/ which is a pro audio site. The HD600 and HD650 are so well established (for very good reasons) for pro use that the HD660S seems to have been overlooked, not least I think because of course the true successor to the HD650 chronology and technically was the HD800, which is also widely used. It’s hard to get pros to part with more money for the HD660S when it has already effectively been superseded and sounds so similar to a well established headphone which is considerably cheaper.
It’s also relevant here to point out that Sonarworks were not impressed by the HD660S, which is probably why they haven’t provided a calibration for it.

I've known many musicians over the years, and engineers, and most have been quite conservative in their gear choices. Better the devil you know. There are reasons Strats and LP's still abound.

I prefer my HD600 for mixing, because I know I can trust it. For casual or critical listening for pleasure, I have many other choices.

(And of all the dozens of guitars I've owned, just 3 Strats and a Guild remain...)

 

[wantan]

....The HD600 and HD650 are so well established (for very good reasons) for pro use that the HD660S seems to have been overlooked,...

...It’s also relevant here to point out that Sonarworks were not impressed by the HD660S, ...

I think you're right on target here. tThe HD660S got some bad press early on, especially with the Inner Fidelity review. I had borrowed a HD660S early on from the local Sennheiser shop with the same results Tyll mentioned in his review. Back then, compared to my HD650, it just fell of. Lacking dynamics, didn't scale, grainy treble. When I bought another HD660S this year in spring I loved it, it sounded great and in a way I prefer it over the other two these days. In retrospect it's hard to say why I perceive this headphone differently today compared to the late 2017 version. Maybe Sennheiser adjusted something after the first bad reviews, maybe my hearing was just off.

Today I'd say the HD660S is one the most underrated headphones in personal audio. It's just great to listen to it and I'm looking forward to an upgraded HD700 one day. I had already loved the HD579 and HD599 which follow a simillar target curve as the HD660S does.

 

[Mike F]

Wantan, it’s certainly been highly speculated that Sennheiser has in the past made unannounced sonic changes to headphones, presumably in response to criticism. The HD650 is a good example. It apparently underwent some sort of revision around the time that the screen surrounding the driver changed colour from black to silver. There were very many people who reported that it became much clearer and less ‘veiled’ (a term which I also dislike!). I think it’s quite possible that Sennheiser did something to the HD660S after its release in response to the criticism it received from Tyll and Sonarworks, amount others. Certainly, you are not the only person to have reported that they were disappointed with an early sample and then be pleasantly surprised with a later one.

 

[Mike F]

Today I'd say the HD660S is one the most underrated headphones in personal audio. It's just great to listen to it and I'm looking forward to an upgraded HD700 one day. I had already loved the HD579 and HD599 which follow a simillar target curve as the HD660S does.

I think the HD660S is the upgraded HD700!

 

[donlin]

I got mine fairly early on (early 2018) but it was still after Tyll's review. I thought they sounded great right out of the box and they caused me to eventually get rid of the Focal Clear that Tyll had raved about around that same time.

 

[kman1211]

I think you're right on target here. tThe HD660S got some bad press early on, especially with the Inner Fidelity review. I had borrowed a HD660S early on from the local Sennheiser shop with the same results Tyll mentioned in his review. Back then, compared to my HD650, it just fell of. Lacking dynamics, didn't scale, grainy treble. When I bought another HD660S this year in spring I loved it, it sounded great and in a way I prefer it over the other two these days. In retrospect it's hard to say why I perceive this headphone differently today compared to the late 2017 version. Maybe Sennheiser adjusted something after the first bad reviews, maybe my hearing was just off.

Today I'd say the HD660S is one the most underrated headphones in personal audio. It's just great to listen to it and I'm looking forward to an upgraded HD700 one day. I had already loved the HD579 and HD599 which follow a simillar target curve as the HD660S does.

It could a silent revision or the quality control wasn’t perfected on them yet or something. I’ve only heard one HD 660 S. I personally didn’t find the HD 660 S(which is an early one) to sound all that similar to the HD 650.

 

[donlin]

I think you're right on target here. tThe HD660S got some bad press early on, especially with the Inner Fidelity review. I had borrowed a HD660S early on from the local Sennheiser shop with the same results Tyll mentioned in his review. Back then, compared to my HD650, it just fell of. Lacking dynamics, didn't scale, grainy treble. When I bought another HD660S this year in spring I loved it, it sounded great and in a way I prefer it over the other two these days. In retrospect it's hard to say why I perceive this headphone differently today compared to the late 2017 version. Maybe Sennheiser adjusted something after the first bad reviews, maybe my hearing was just off.

Today I'd say the HD660S is one the most underrated headphones in personal audio. It's just great to listen to it and I'm looking forward to an upgraded HD700 one day. I had already loved the HD579 and HD599 which follow a simillar target curve as the HD660S does.

Agree that it is a very underrated headphone. A bad review from Tyll is the kiss of death. Now that he's retired I don't think there is anybody else with that much power over the fate of a headphone.

 

[Mike F]

It could a silent revision or the quality control wasn’t perfected on them yet or something. I’ve only heard one HD 660 S. I personally didn’t find the HD 660 S(which is an early one) to sound all that similar to the HD 650.

Well, I’m going from one to another listening to Sting on my iPhone, and I can only say that to me they do sound very similar. More difference was apparent on higher end gear. But, I really can’t find very much negative to say about the HD660S, it’s only a question of the small differences in comparison to the HD650 and ones preference. The jury is still out!

 

[equalspeace]

Do you find that the 660s sounds fuller than the 650 from the iPhone?

Well, I’m going from one to another listening to Sting on my iPhone, and I can only say that to me they do sound very similar. More difference was apparent on higher end gear. But, I really can’t find very much negative to say about the HD660S, it’s only a question of the small differences in comparison to the HD650 and ones preference. The jury is still out!

 

[Mike F]

Do you find that the 660s sounds fuller than the 650 from the iPhone?

Actually, surprisingly, no. Louder, certainly, but when I match the volume (two clicks more for the HD650) then if anything I find the HD650 has a bigger sound. The HD660S sounds more focused, and arguably in a way better balanced, but the HD650 is the bigger fuller sound. However, I am listening at relatively low volumes. On my iPhone 6S I have the volume set to two bars from maximum for the HD650 and the HD660S four bars from maximum. Do I generally prefer the HD650 because my listening volumes are so low? I think that might have something to do with it.

 

[equalspeace]

I respect the way you hear it, but I have to say I'm somewhat surprised by this response. I hear a huge difference on my DAPs, cept for when I play both through the R5. The 660s sounds more effortless from all of them though. This should apply to an iPhone as well

Actually, surprisingly, no. Louder, certainly, but when I match the volume (two clicks more for the HD650) then if anything I find the HD650 has a bigger sound. The HD660S sounds more focused, and arguably in a way better balanced, but the HD650 is the bigger fuller sound. However, I am listening at relatively low volumes. On my iPhone 6S I have the volume set to two bars from maximum for the HD650 and the HD660S four bars from maximum. Do I generally prefer the HD650 because my listening volumes are so low? I think that might have something to do with it.

 

[Mike F]

I respect the way you hear it, but I have to say I'm somewhat surprised by this response. I hear a huge difference on my DAPs, cept for when I play both through the R5. The 660s sounds more effortless from all of them though. This should apply to an iPhone as well

I presume that you’re carefully matching the volumes? Without doing so the HD660S is bound to sound fuller and more effortless.

 

[equalspeace]

Of course. The thing that's great about the 660s is that it basically eliminates the need for Senn fans to have a home system, completely. If you have that type of system it's nice and will work fine, but Senn opened up the game for DAP users. These phones work beautifully on DAPs, even my low powered NW-A35. Def can't say the same for 6xx.

I presume that you’re carefully matching the volumes? Without doing so the HD660S is bound to sound fuller and more effortless.