Sennheiser HiRes Audiophile Headphone (HD 660 S)

Product Information

Talking about the price, the HD 660s being a new model, at the beginning of the life cycle, 500 EUR seems to be a reasonable price for what they are. The HD 650 had the same release price. At the moment the HD 650 can be bought for much less than the official original price, but let’s not forget that they’re 14 years old, it’s just normal to be much cheaper now. Their design and fit is a little more special than that of the fairly conventional-looking HD 660 S too. However, while I no longer have the HD 700 to hand for a direct A/B test, comparisons with other contemporaries suggest that pair is “different” rather than flat-out better. So they didn’t improve the build quality of the HD660 S over that of its predecessor so how about its comfort? Ummm, depends on what you like really. Where as the HD650 felt like “sand conforming to your hand” as I said in my HD650 review, the HD660 S is like the bear hug a relative gives you after not seeing you in a really long time. It’s not that it hurts, but it’s quite tight, and as a personal opinion, it’s way too much so for my preference so I PERSONALLY (so do at YOUR OWN RISK) bent the metal band on each side of the ear pads just slightly and it made it, to me, considerably better. These headphones are a follow-up to the Sennheiser HD 650, considered a classic pair for well over a decade now. Sennheiser retains the warm, accessible tone for the HD 660 S, making this pair easy to recommend to virtually anyone who can afford the high price. 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)

My interests/hobbies are fishing and relaxing to audio products and reviewing them to help other decide on what products would work for them. Few things make me as an audio enthusiast/reviewer feel more accomplished than when someone tells me that I helped them find the type of sound they've always been looking for. Honestly, I can’t imagine a way to get good dynamics or a holographic experience out of a smartphone. 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 AnalysisTheHD 660 S2's upgrades look like sensible ones, butSennheiser nevertheless has a big task on its hands as it tries to satisfying the fussiest demographic of music lovers. 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. The DT880 initially comes across as the most detailed of the three because of its brightness and more aggressive presentation. Upon closer listening, it maintains a slight edge over either Senn in detail retrieval in the bass and the treble. The 6XX and the 660s are slightly more detailed in the midrange than the DT880. The 6XX probably is the one with more resolution in the mids, and the 660s is the one that’s smoother and more forgiving. Both of these qualities have advantages in certain situations. Yes, they are still here, they haven’t left. Probably the biggest virtue of these headphones is the very present mids that seem to infuse joy directly into your central nervous system.

The sub-bass though sometimes leaves to be desired. The sensible use of an equalizer can solve the problem, but I don’t recommend adding more than 4-5dB in this area because the driver can start clipping and distorting when the volume is pushed above a certain point. As a sign of repentance, we bring out the fresh review of this new model, and at the end of this article we will compare it with the predecessors HD 600 and HD650, which we’ve been using for many years now. 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. Have you heard the phrase “Sennheiser veil”? Senns are not detail-forward so to many they can sound veiled when they are first put on. It took me awhile to drop this feeling after doing weeks of listening to the likes of the Audeze LCD-24, HiFiMan HE1000V2, and Abyss Diana Phi. However, Senns are actually quite detailed at their price points; they’re just subtle about it. Once that veiled feeling wears off, there’s a fair amount going on. The 660s is no exception here. It’s reasonably resolving in the mids and lower treble in particular. Room reverb, many vocal subtleties, etc. are presented well.

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?