Here are my impressions about the HD660S. (I apologize for my "sketchy" English)
I love the 500$ segment: there are a lot of peculiar headphones, whith samples of flagship's qualities, usually a good musicality, with some more or less important flaws usually in the mid-high frequencies. So I learned to like listening with the Beyer T90 or the Sennheiser HD700.
The aim of the HD660S can be tricky: continue the legendary lineage of correctness and musicality of the HD6xx series, while injecting something special to justify the price tag.
A lot has already been said about construction and related things, so I will skip this with a simple consideration: it's an HD6xx headphone, period.
Let's talk about the sound: I've listened to the headphones with several amplifications, with different powers and more importantly different output impedances.
OVERALL SOUND
The HD660S has the sound of an headphone of the 600 series. We are far from the 700 and 800 sound landscapes, and comparison with these two headphones can basically be reported to what was written about the 600/650. Instead I will stress the differences between 660S and 600.
The HD660S has a dense, balanced, warm but still clear, contrasted, and competent sound, which will satisfy those who like a perspective close to the instruments and a more vigorous than airy sound. The headstage is more contracted and "in-head" than the HD700 or HD800, it's even more intimate than the HD600 but with a better feel of the environment compared to the latter.
COMPARISON TO THE HD600 LISTENING TO SELECTED MUSIC
PAUL SIMON - GRACELAND
The HD600 sounds airier and softer, while the 660S sounds closer and with more impact, with a more powerful bass, but also with a more prominent particular part of the high frequencies. Paul Simon's voice has a clearer tonality in the HD600, while is darker and a bit back in the mix with the HD660S. The transients are better outlined in the HD660S, which, directly compared to the HD600, appears as the more modern headphone, with better resolved frequency extremes. The good old HD600 exhibit a hint of acidity in the voices, which is absent in the HD660S. On the other hand the HD660S seems sometimes to "mute" some harmonics, while the HD600, even if more "squeaky", seems to flow more naturally across the mid frequencies. But it's difficult to say which one is closer to the "truth". The headstage seems to me more over the head with the HD600, and more intimate and "in-head" with the HD660S, which however has probably a better depth of image.
ALAN PARSON'S PROJECT - TALES OF MISTERY AND IMAGINATION
In the song Tell-Tale Heart there is a bows attack (about a minute and a half from the beginning) I often use to test the timbre vividness, while the low end of this recording is a very good test in this range. The bows rubbing "roughness" is more evident in the 600, while the 660S masks a bit of this mid-high frequency component, compensating with a more modern and less "mid-centric" sound. The bass is more evident and punchier in the 660S. Overall, in A/B comparison, the 600 sounds like the "old" headphone, while the 660S is the "remastered" one. The electric bass is softer in the 600, and has more impact on the 660S. In the orchestral parts, the 660S has finer grain and the listening point is placed more on the director's podium than among the audience. The high frequencies are refined, clear, detailed and have great resolution. Cymbals & co have definitely a very well-defined harmonic spectrum. Beautiful expressivness.
MAHLER, SYMPHONY N.8, ABBADO / BERLINER PHYLARMONIKER / DG
I begin to understand this new headphone. As before, compared to the HD600, the HD660S is the one that sounds with the most powerful frequency extremes, fuller and cleaner. There is a somehow attenuated mid-high frequency area compared to the 600, balanced by a rise slightly above it. This contributes to the feeling of a cleaner sound, but in direct comparison the voices seem timbrically a bit "muted". But if one get used to the 660S' sound, it seems that maybe the 660S is right, while the 600 emphasizes some harmonic components perhaps a little more than the necessary (but very pleasantly). Nevertheless, some chorus lines seem slightly better outlined with the 600, while on the other hand the 660S has better positioning of the orchestra and chorus sections. Overall the 600 seems timbrically more "phoney" sounding than the 660S.
SIBELIUS - LEMMINKAINEN AND THE MAIDENS OF THE ISLAND, STEIN / SUISSE ROMANDE / DECCA
At circa 6:30 minutes of this movement there is a beautiful effect of rubbing of the violins, which (live) gives an exceptional emotional experience, it seems to feel the freezing northern winds on the skin. It's a very difficult part to reproduce (I think it's basically impossible to reproduce the experience that you feel in the live concert hall). Given the somewhat discontinuous performance of the 660S around the mid-high frequencies, I did not expect to hear the newcomer reproducing better the breath of this magnificent moment. It is not clearer, but it's better placed in the soundstage, it has more breath, where the 600 loses room sensation (maybe for the lower bass presence). The 660S is a really good headphone.
RODRIGO - FANTASIA PARA UN GENTILHOMBRE, SEGOVIA / DG
How close is the guitar with the 660S! It's exciting but there's less sense of distance of the stage. Nevertheless, the timbre of the strings are exciting, albeit slightly resonant on the lower end, while the 600 has a more "acid" sound. The reverb of the recording venue is more evident in the 660s.
BIBER - SONATA A 10, REQUIEM A 15, SAVALL / ALTAVOX
With this recording the perspective difference between the two headphones is clear. The 600 sounds more distant, while with the 660S we are virtually in the middle of the stage. It's not very realistic, but the introspection in the harmonic structure of the instruments is exciting. The 660S has the best harmonic resolution: yes, this time the 600 loses harmonic content in comparison.
But the 600 renders magnificently the voices in the indescribable Introitus of the Requiem A 15, while the 660S seems to lose some expressive nuances.
PAT METHENY GROUP - IMAGINARY DAY
The performance of the 660S is really remarkable: it's punchier, more contrasted and extended than the HD600. (the sound of the cymbals is timbrically almost "suffocated" in the 600, while it's exceptionally harmonically resolved in the 660s, in absolute terms). The "on-stage" feeling of the 660S does a good job here. The 600 is very nice, but can't really compete with the 660S here.
SOME CONCLUSIONS ...
I think that the new HD660S is a remarkable headphone, pleasing and enjoyable to listen to. Its dense, and contrasted sound balance it's not as "heavy" as the 650, it remains way more agile and can really be an update of the 600, except maybe for a "too near" sound perspective. The closer but better sized perspective is exciting, except when it becomes too "dense" (especially if you're used to the landscapes of the HD800). The grain seems finer than the 600, and the resolution of the high frequency is better too. Sometimes there are some timbrical and expression information that seems slightly "muted", but it is a very little price to pay compared to the overall performance. Also because sometimes it's the opposite, and it's the 660S the more expressive headphone. In terms of "music flow", the more "shy" 600 seems sometimes to perform better, but in A/B comparison it sounds more "mid-centric" and less resolved. The 660S is clearly the fuller-sounding headphone. The harmonic resolution on cymbals, triangles & co is absolutely excellent.
I expect great success for the 660S, it is perhaps one of the most balanced headphone in its price range, able to span on all music genres without fear. Its "500$ specialization" is this warm, dynamic and contrasted balance, coupled with a beautiful timbrical accuracy.
[HINTS TO HD700 and HD800S COMPARISON:
- The HD700 is less correct and less timbrically competent, but its soundstage, warmness and the particular high frequency detail gives to this headphone a somewhat special status (which you can love or hate). If you like its sound perspective, the Hd660S can't compete. Instead, if strict timbrical accuracy is what you seek, the 700 will have some difficulties to compete with the HD660S.
- The HD800S is the flagship one and has another approach. A/B compared after getting used to the 660S it seems almost too light; 660S instead seems to be too closed and dense if you get used to the sound of the 800S. Without the "ear habitude" bias, there is no match for expressiveness, elegance and rendering capabilities of at least all the acoustic situations, in favor of the 800S, not to mention the huge difference in the soundstage, which gives the necessary breath to the symphonic orchestra, something the 660S has some difficulties to deal with. Moreover, the 800S clearly dig deeper in the bass.]
I love the 500$ segment: there are a lot of peculiar headphones, whith samples of flagship's qualities, usually a good musicality, with some more or less important flaws usually in the mid-high frequencies. So I learned to like listening with the Beyer T90 or the Sennheiser HD700.
The aim of the HD660S can be tricky: continue the legendary lineage of correctness and musicality of the HD6xx series, while injecting something special to justify the price tag.
A lot has already been said about construction and related things, so I will skip this with a simple consideration: it's an HD6xx headphone, period.
Let's talk about the sound: I've listened to the headphones with several amplifications, with different powers and more importantly different output impedances.
OVERALL SOUND
The HD660S has the sound of an headphone of the 600 series. We are far from the 700 and 800 sound landscapes, and comparison with these two headphones can basically be reported to what was written about the 600/650. Instead I will stress the differences between 660S and 600.
The HD660S has a dense, balanced, warm but still clear, contrasted, and competent sound, which will satisfy those who like a perspective close to the instruments and a more vigorous than airy sound. The headstage is more contracted and "in-head" than the HD700 or HD800, it's even more intimate than the HD600 but with a better feel of the environment compared to the latter.
COMPARISON TO THE HD600 LISTENING TO SELECTED MUSIC
PAUL SIMON - GRACELAND
The HD600 sounds airier and softer, while the 660S sounds closer and with more impact, with a more powerful bass, but also with a more prominent particular part of the high frequencies. Paul Simon's voice has a clearer tonality in the HD600, while is darker and a bit back in the mix with the HD660S. The transients are better outlined in the HD660S, which, directly compared to the HD600, appears as the more modern headphone, with better resolved frequency extremes. The good old HD600 exhibit a hint of acidity in the voices, which is absent in the HD660S. On the other hand the HD660S seems sometimes to "mute" some harmonics, while the HD600, even if more "squeaky", seems to flow more naturally across the mid frequencies. But it's difficult to say which one is closer to the "truth". The headstage seems to me more over the head with the HD600, and more intimate and "in-head" with the HD660S, which however has probably a better depth of image.
ALAN PARSON'S PROJECT - TALES OF MISTERY AND IMAGINATION
In the song Tell-Tale Heart there is a bows attack (about a minute and a half from the beginning) I often use to test the timbre vividness, while the low end of this recording is a very good test in this range. The bows rubbing "roughness" is more evident in the 600, while the 660S masks a bit of this mid-high frequency component, compensating with a more modern and less "mid-centric" sound. The bass is more evident and punchier in the 660S. Overall, in A/B comparison, the 600 sounds like the "old" headphone, while the 660S is the "remastered" one. The electric bass is softer in the 600, and has more impact on the 660S. In the orchestral parts, the 660S has finer grain and the listening point is placed more on the director's podium than among the audience. The high frequencies are refined, clear, detailed and have great resolution. Cymbals & co have definitely a very well-defined harmonic spectrum. Beautiful expressivness.
MAHLER, SYMPHONY N.8, ABBADO / BERLINER PHYLARMONIKER / DG
I begin to understand this new headphone. As before, compared to the HD600, the HD660S is the one that sounds with the most powerful frequency extremes, fuller and cleaner. There is a somehow attenuated mid-high frequency area compared to the 600, balanced by a rise slightly above it. This contributes to the feeling of a cleaner sound, but in direct comparison the voices seem timbrically a bit "muted". But if one get used to the 660S' sound, it seems that maybe the 660S is right, while the 600 emphasizes some harmonic components perhaps a little more than the necessary (but very pleasantly). Nevertheless, some chorus lines seem slightly better outlined with the 600, while on the other hand the 660S has better positioning of the orchestra and chorus sections. Overall the 600 seems timbrically more "phoney" sounding than the 660S.
SIBELIUS - LEMMINKAINEN AND THE MAIDENS OF THE ISLAND, STEIN / SUISSE ROMANDE / DECCA
At circa 6:30 minutes of this movement there is a beautiful effect of rubbing of the violins, which (live) gives an exceptional emotional experience, it seems to feel the freezing northern winds on the skin. It's a very difficult part to reproduce (I think it's basically impossible to reproduce the experience that you feel in the live concert hall). Given the somewhat discontinuous performance of the 660S around the mid-high frequencies, I did not expect to hear the newcomer reproducing better the breath of this magnificent moment. It is not clearer, but it's better placed in the soundstage, it has more breath, where the 600 loses room sensation (maybe for the lower bass presence). The 660S is a really good headphone.
RODRIGO - FANTASIA PARA UN GENTILHOMBRE, SEGOVIA / DG
How close is the guitar with the 660S! It's exciting but there's less sense of distance of the stage. Nevertheless, the timbre of the strings are exciting, albeit slightly resonant on the lower end, while the 600 has a more "acid" sound. The reverb of the recording venue is more evident in the 660s.
BIBER - SONATA A 10, REQUIEM A 15, SAVALL / ALTAVOX
With this recording the perspective difference between the two headphones is clear. The 600 sounds more distant, while with the 660S we are virtually in the middle of the stage. It's not very realistic, but the introspection in the harmonic structure of the instruments is exciting. The 660S has the best harmonic resolution: yes, this time the 600 loses harmonic content in comparison.
But the 600 renders magnificently the voices in the indescribable Introitus of the Requiem A 15, while the 660S seems to lose some expressive nuances.
PAT METHENY GROUP - IMAGINARY DAY
The performance of the 660S is really remarkable: it's punchier, more contrasted and extended than the HD600. (the sound of the cymbals is timbrically almost "suffocated" in the 600, while it's exceptionally harmonically resolved in the 660s, in absolute terms). The "on-stage" feeling of the 660S does a good job here. The 600 is very nice, but can't really compete with the 660S here.
SOME CONCLUSIONS ...
I think that the new HD660S is a remarkable headphone, pleasing and enjoyable to listen to. Its dense, and contrasted sound balance it's not as "heavy" as the 650, it remains way more agile and can really be an update of the 600, except maybe for a "too near" sound perspective. The closer but better sized perspective is exciting, except when it becomes too "dense" (especially if you're used to the landscapes of the HD800). The grain seems finer than the 600, and the resolution of the high frequency is better too. Sometimes there are some timbrical and expression information that seems slightly "muted", but it is a very little price to pay compared to the overall performance. Also because sometimes it's the opposite, and it's the 660S the more expressive headphone. In terms of "music flow", the more "shy" 600 seems sometimes to perform better, but in A/B comparison it sounds more "mid-centric" and less resolved. The 660S is clearly the fuller-sounding headphone. The harmonic resolution on cymbals, triangles & co is absolutely excellent.
I expect great success for the 660S, it is perhaps one of the most balanced headphone in its price range, able to span on all music genres without fear. Its "500$ specialization" is this warm, dynamic and contrasted balance, coupled with a beautiful timbrical accuracy.
[HINTS TO HD700 and HD800S COMPARISON:
- The HD700 is less correct and less timbrically competent, but its soundstage, warmness and the particular high frequency detail gives to this headphone a somewhat special status (which you can love or hate). If you like its sound perspective, the Hd660S can't compete. Instead, if strict timbrical accuracy is what you seek, the 700 will have some difficulties to compete with the HD660S.
- The HD800S is the flagship one and has another approach. A/B compared after getting used to the 660S it seems almost too light; 660S instead seems to be too closed and dense if you get used to the sound of the 800S. Without the "ear habitude" bias, there is no match for expressiveness, elegance and rendering capabilities of at least all the acoustic situations, in favor of the 800S, not to mention the huge difference in the soundstage, which gives the necessary breath to the symphonic orchestra, something the 660S has some difficulties to deal with. Moreover, the 800S clearly dig deeper in the bass.]
I didn't find the T90 so "picky" with recordings, but I understand that sometimes can be bothersome given that peculiar frequency response in the mid-high frequencies. Anyway, I'm more and more in love with the sound of this headphone!