Sennheiser HiRes Audiophile Headphone (HD 660 S)

Product Information

If you already have the HD 650 or the HD 600, it’s hard for me to recommend something that is a bit better. You have to give them a listen and decide for yourselves. It comes with…the same exact cable connectors as the other two. In a way, I’m sure this is appealing to longtime fans who have spent on aftermarket cables that they’d like to carry on over – but the connectors on these are some of my least favourite available for any headphone. 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. The HD 660S comes in at an impedance of 150ohms and a sensitivity of 104dB. I personally found them to have plenty of volume on most devices I tested, like my MacBook Air and Nintendo Switch. However, I did think that they sounded better when being fed power from my amplifier. When running them on devices without a discrete amplifier I thought that they sounded a little more compressed, so I will list an amplifier as recommended for these. Still, these are very efficient, so it does not have to be a very powerful amplifier. Amplifiers like the Liquid Spark and JDS Labs Atom will be more than enough to drive these very cleanly. 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.

The HD 660 S is designed for more demanding music enjoyment at home, while also allowing for professional audio applications, such as mixing and editing tasks. What’s New? For the HD660 S2, Sennheiser revised the coil of the S2, and it now matches the 300-ohm impedance of the legendary HD 600 & HD 650. This new coil also provides higher magnetic force and electrical dampening for cleaner impulse response. The surround – according to Sennheiser – is now more compliant too, dropping the resonant frequency to 70 Hz . Considerable effort also went into optimizing the airflow around the transducer. There’s more sensitivity over the entire frequency spectrum because the magnet´s air gap works more efficiently now. Taken together, these measures result in even greater precision, speed, and resolution — with double the sound pressure at the lowest frequencies. The 660s is a fine-sounding headphone. I can listen to it and enjoy it for extended periods of time. Nonetheless, this sound section is a bit shorter than I often do because I think the big story with the 660s is found in the… This is why I feel so strongly about the initial presentation of a product, and I feel it’s truly a shame more people don’t. But with all that aside, let’s discuss how this products introduced itself shall we? I believe I received a very nice “handshake” with the HD660 S, as I did with its predecessor the HD650. Sennheiser includes a very nice cardboard box that is really just a smaller version of the HD800 S box minus the nice silky material and the stop strap. The box itself, like the HD800 S, is my EXACT want in a headphone box. The exterior si super simplistic as in all it shows is a picture of the product and its name. This, to me, shows the competency and confidence of an audio manufacture.By doing this I see it as them telling their customers listen to my product and let it speak for itself; let it SHOW you what it can do instead of my boggling down the box with fancy words and look-at-me’s so that I can pretend to be competent. And for a company as legendary as Sennheiser, who’s over 70 year experience shows, they’ve got more than enough competence. So in other words, before I even get into this box, I’m extremely excited to put it on my head and see what it can do.

How well does the Sennheiser HD 660S block out noise?

The Sennheiser HD 660 S are comfortable, have a great soundstage and a non-fatiguing combination of clarity and rich tone. I'll not wax poetic this time regarding the long and storied history and my experiences with the HD 6xx family of Sennheiser headphones. For that, simply go have a look at my " The Very Important Sennheiser HD 580, HD 600, and HD 650" review. So again I’ll state that the “handshake” given to me from Sennheiser was firm and filled with confidence, which is exactly what I’ve come to expect from Sennheiser. Electrocord is not Chesky or Reference Recordings, I know, but I consider it a quality recording for 1972, from which nowadays many could learn a thing or two. I have heard that the age of the pads makes a difference – both the HD650 and HD600 pads are not decrepit and have been changed not too long ago by the looks of them.

The comfort while being worn for long periods of time is very good, and with HD660S, you can walk and even to some heavier exercise without damaging them, or without feeling any fatigue, and it surely is possible to wear them for prolonged periods of time without much issue, but you should mind the cable, which is quite long. There are no microphonics, and no other issues we were able to notice, but HD660S does not isolate from the outside noise (at all), and most music being played through them will also be heard outside, so they are quite open in this aspect. 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. 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. For this sound section I will be going over the HD 660S’ tonal and technical performance while drawing comparisons to some of its competitors, as well as some of Sennheiser’s other offerings; namely the DROP X Sennheiser HD 6XX and HD 58X Jubilee. Bass It’s funny that even if, from my understanding, the HD 660 S is meant to replace the HD 650, the HD 660 S resembles the HD 600 more than the HD 650.For now it's sufficient to state that the Sennheiser HD 600 and HD 650 are probably the most highly regarded enthusiast headphone in the world, and I highly recommend both. The HD 650 is a bit too warm sounding for me (just a bit), and the HD 600 is my favorite of the two. When changing the HD 650 with the HD 660S after a non-stop 2 hour listening to the HD 650, I can feel that the veil has lifted, the mid-bass stops rattling and clipping and the harmonic distortion feels lower. As before, the HD 660S2 headphones are designed for the critical listener. Hand selected speakers are carefully paired, giving these headphones the most consistent sound between channels. Precision, stainless steel fabric diaphragms deliver life-like realism for a true-to-life sound. There’s little-to-no sound isolation here, so don't take these headphones with you on your commute. (Image credit: Future/TechRadar/Henry St Leger) Sennheiser HD-660S2 review: Price & release date