Sennheiser HiRes Audiophile Headphone (HD 660 S)

Product Information

Buy the Sennheiser HD 660S at headphones.com at the best price, and its the best return-policy available. 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. The HD 660 S is an elegantly designed piece of high-quality engineering that indulges the demanding listener with aural precision and great wearing comfort. Interestingly, despite the fact that I don’t feel the notes flying a few meters from me, I can clearly hear the angle at which they are emitted, a good sign that the holography is in effect. The frequency range is expanded to 10Hz – 41kHz which is wider than the HD 650. One other notable feature promised by the HD 660 S is “crisp bass”. How’s The Build and Fit? Now, HD660S is not a portable headphone. Even trying to consider them to be one is wrong. We did take them on a little adventure in the Izvor Park in Bucharest to test this, but they still are not quite that portable, they would probably fit best with your favorite desktop and armchair setup.

The impedance is lowered to 150 Ohm. Sennheiser are marketing these headphones as compatible with portable devices (smartphones and music players). The HD 660 S still has the somewhat tight clamping force, which can be remedied as mentioned above. Once set, the HD 660 S has the same quite comfortable, head-hugging fit and light weight of its predecessors. There are a few subtle differences. Of course, this may not be best for all users since weight can add to the feeling of rigidness and reliability of a product, but still, it is impressive that Sennheiser managed to pull this off.

How does the Sennheiser HD 660S2 sound?

I now realize that none of the models in the HD 6xx series, including HD 660 S, offers a convincingly large and expanded enough soundstage. The soundstage is somewhat compact and intimate, but surely not claustrophobic. I would categorize it as a medium-sized soundstage, not too large (like HD 800), but also not so close as to make me feel on the stage with the band. Strong believers of burn-in should know that the HD660S is a very new unit while the HD650 and HD600 are much, much older.

Image credit: Sennheiser) Analysis: Will these new Sennheiser’s pass the test with audio’s toughest crowd? They have an excellent soundstage. It’s wide, expansive and superb stereo imaging and spatial imaging lets your ears explore arrangements much better than almost any closed pair at this price. The padding in the new HD660 S feel very firm to the touch and offer a really nice level of both give and support. This may be because these are a brand new pair and my HD650 is, how should I say, well experienced, the padding looks to be a little bit deeper than my ol faithful HD650. This is a good thing because my ears no longer touch and rub against the cloth covering the drivers. The comfortable soundstage and detailed imaging hasn’t changed much. This was kinda difficult to determine because the forwardness of the mids and upper bass makes the soundstage sound a bit closer than the original HD650 did but when playing normal classical/instrumental music, at least me personally, I can’t hear a notable difference between the two in the soundstage and detail side of things. 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.

How does the Sennheiser HD 660S sound?

At the end of the day, you're probably wonder where is the HD6XX line headed towards, and we feel it is headed towards greatness. Sennheiser has shown great respect for their customers, and they have shown improvements organic with their customers demands when releasing the HD660S, which is a more versatile headphone than both the very clean, but slightly clinical sounding HD600, and the too lean and too smooth HD650. They simply made a headphone better than either, one that not only bests both, but will also be hard to beat for a long time to come, as its predecessors were iconic headphones for many years so far. 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. In the long term this could induce listening fatigue, but even so, the timing is more correct and true to reality.

The HD 650 and HD 600 have always been categorized as being more musical than the other models and this has been achieved through the good reproduction of the midrange. The depth of the soundstage is pretty good. With my eyes closed, I can walk myself through the quality recordings. On well recorded material I could never hear the sound becoming too crowded.In conclusion, I don’t recommend you to plug them directly into a smartphone, but if you add a portable amplifier to the mix, things will get radically better. In my opinion, the HD 660 S is the true reference in the HD 6xx line, with the HD 600 coming second and the HD 650 coming last, with a more colored sound. Sennheiser would have you believe that you can just go and run the HD 660 S straight from a smartphone. While it’s twice as easy to power this headphone it’s a bit of a stretch to use a smartphone directly. I tried it and the sound did play out but I found myself pushing the volume all the way up and needed more. So do yourself a favor and always use an amplifier with the HD 660 S. Final Analysis What I enjoyed immediately after switching to the HD600 was this sense of depth the sound gained over the HD660S. While the newer headphone is punchier and more impactful, it can sound thin and strident compared to the HD600. grams feels like nothing to me now after such a long time with the Focal and ZMF headphones. That being said, I find the comfort to be largely affected by the amount of clamp these can have while new - a few hours in and I was feeling the pain. Once on your head, however, they stay put so you can headbang away without fear of them falling off. The cushioning on the headband is adequate, considering its low weight.

Now, the sound signature I personally favor is a relaxing, warm and sensual sound that just drifts me away in the emotional experience of the music being performed. Yes, accuracy is still important but I will happily sacrifice some of that if I'm presented with a clean, warm sound that can wisp me away into an experience that makes me yearn for more. What more can I say? We have the same built and design that we are familiar with for more than 26 years.Maybe the halved impedance would lead you to believe that the sensitivity is much better, but you’d be wrong. In reality the headphones are 2dB more efficient that the predecessors, so in real world tests they sound just a little bit louder. I mostly tested the Sennheiser HD-660S2 headphones at home, using Spotify, YouTube and Twitch videos and even my Nintendo Switch to test a variety of sources. (Image credit: Future/TechRadar/Henry St Leger) But let me now talk about the individual characteristics of the sound signature so that I may be able to convey my thoughts on the HD660 S better. These days, portable headphones tend to be at the top of most buyers’ to-buy lists. However, the Sennheiser HD 660 S prove full-size open headphones such as this are generally a better choice if you simply want a pair to use at home.