sennheiser hd 660 s review-did-you-know-these-15-big-facts

Sennheiser HD 660 S Review [October 2023]: Did You Know These 15 Big Facts?

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A cut above open back audiophile headphones that is very good for critical listening. But has it got all you love? We will see in Sennheiser HD 660 S Review.

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SENNHEISER HD 660 S - HiRes Audiophile Open Back Headphone

the HD 660 S impressed me with its performance delivery. There is another pair of headsets, the HD650’s. Though these are not the best headphones, I still continue to enjoy music a lot with them.

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Sennheiser is one of my few favorite brands in the collection of open-ear headphones. It has been around for many years.

And I must say it’s one of the most respected companies in the audio market segment. I have been writing on headphones of various brands for quite some time.

Indeed, the HD 660 S impressed me with its performance delivery. There is another pair of headsets, the HD650’s. Though these are not the best headphones, I still continue to enjoy music a lot with them.

I don’t have any doubt that Sennheiser’s HD 600 lineup is the most successful headphones. And the most exciting audiophile headphones ever created.

This series has been in the market for almost 20 years and are still the listener’s favorite. The open-back headphones came up very well to match user expectations. And the Sennheiser HD 660S lives up to the tradition.

In today’s review, we take a closer look at the new full-size open-back headphones, the HD 660 S.

The Sennheiser HD 660 S are very good open-back headphones for critical listening. They deliver excellent audio reproduction.

I am very happy that I did not feel fatigued wearing them for long. These are is good and comfortable enough for long listening sessions. Yet, they are very firm, even firmer than other Sennheiser headphones I have used.

By design and nature, the open-back headset doesn’t block noise. It also feels a little annoying there is a lot of sound leakage.

Thus, it’s better used in a less noisy or quiet listening room. But I am happy to see the HD 660 S rocks the traditional body of the HD 600 series.

The over-ear open-back headphones come with a sleek all-matte black finish. The major part of the HD 660S is made up of plastic material.

The only exceptions are the outer grille and inner headband. Still, this is one of the most durable and reliable designs in the lineup.

Let’s see what are the 15 big facts you wish you knew earlier in this Sennheiser HD 660 S Review.

1. What is in the Box- Sennheiser HD 660 S Open Back Headphones?

The packaging of the Sennheiser HD 660s comes with all articles that is definitely on the more minimalistic side.

It includes just about everything you need your headset to get going. It includes the following in the box:

  • Headphone set
  • 2 Cable- a ¼” termination, 4.4mm balanced
  • Pentaconn plug/¼’ to 3.5mm adapter
  • Storage box
  • User manual

2. Sennheiser HD 660 S Open Back Headphones Release Date?

Sennheiser HD 660 ope-back headphones were officially released in October 2017 and made available in the audio market for its consumer. Ever since there has been many update and revisions.

3. Sennheiser HD 660 S Open Back Headphones Design and Build

The design and build of the Sennheiser HD 660 S open-back headphones look good. I have no complaints to submit here, to be frank.

It is interesting. Like many other headphones, the exterior of the Sennheiser HD 660 S is made up of plastic material.

But, the inner headband and grille are made up of aluminum, and it doesn’t feel cheap or flimsy at all. Due to the plastic, these headphones are very light and very comfortable to wear.

The HD 60 series is very durable. And you will love to see it will last for decades with a little care and maintenance. And I don’t doubt it at all. Why should you either?

The HD 660S is available in matte black and anthracite finishes. This is a high-end aesthetic that combines both contemporary style and timeless elegance. This is the typical Sennheiser design.

But I like Sennheiser made a wise decision to tweak the existing design. When I picked up the new Sennheiser HD660s, I saw the look and feel of the HD650 and HD600 headphones, at first glance.

But looking with an eye for details gives a different feel that is easy to distinguish. The main differences I could see are in the finish, grille, and driver design.

Ever since the Sennheiser HD600 came out, there has not been a drastic change in design. I am sure the design of the Sennheiser HD600s will last for a long. May be another 20 years.

Beside being good headphones, the HD 660s also have minor flaws in their construction. The frame of the headband is a thin metal plate that is somewhat durable but not flexible. The joint where the headband meets the yolk is very fragile. It seems to be a weak point in the build.

On the plus side, the plastic used is pretty solid. It even comes with a detachable cable that is easy to replace. It has improved durability.

4. Features and Specifications- Sennheiser HD 660 S Open Back Headphones

I am a fan of Sennheiser. I have been using these headphones since my early days in graduation.

The Sennheiser HD 660S features a new transducer design. This improves control of cone movement by well crafted precision stainless steel mesh. The steel mesh conforms to the cone’s contours.

The Sennheiser HD 660S also features a very lightweight aluminum voice coil. It’s a real joy to see that it delivers the highest impulse fidelity.

The HD660 S converters are selected with utmost care and hand-paired. This gives 1 dB left/right matching tolerance for excellent accuracy.

Needless to say, Sennheiser built its reputation over the years. Their practical headphones let the sound speak for themselves.

The Sennheiser HD 660S over-ear headphones have a large foam lined black hinged lid box. There are three cables with the cans. Two 3-meter “Y” cables and a short adapter cable.

I am not sure why the case is there. But that is there. The open-back design needs me to have a separate bag to carry my headset around. I also missed the folding hinge that could make the headset a little compact and thicker.

Thus, I am impressed, the headphone is best suited for home use. Yet, I am happy these over-ear headphones have ample padding inside the headband. And it’s a luxury to have such soft padding around the 70mm x 40mm ear cups.

These open-back headphones weigh 260g. I feel very light over my head. These are very comfortable to use for long periods of time.

Lovely! There is enough clamping force. Moreover, the ear cups have a small swivel range so they stay firmly to the contours of your head.

There is a notch in the headband. This allows you to remember your sizing. But only by counting the clicks made with each change of the somewhat stiff metal mechanism.

I like the fit and finish of this black headset. The Sennheiser branding in silver is minimal and looks classy. I didn’t like the black plastic tips of the cable on the left and right earcups.

Earlier HD series had a red connector on the right side for easy channel identification. I also love the markings on the headphones.

They look very subtle, carved into the inside of the band just above the padding. It’s very easy to figure out how to wear when the light is weak. The silver ‘S’ logo on each ear cup!

5. Sennheiser HD 660 S Open Back Headphones- Battery Life

The Sennheiser HD 660S over-ear headphones are wired headsets. Thus, they don’t have battery.

6. Sennheiser HD 660 S Open Back Headphones- Wearing Comfort

The Sennheiser HD 660S over-ear headphones weigh only 260g. This seems to be one of the best selling propositions. I also mentioned the clamping force in the foregoing section. The clamping force is enough and quite noticeable.

Thus, the headset stays very firmly over the head. Also, the ear cups have very good paddings. The clamping force combined with padded ear cups feels a bit tight at the start. They also put a little more pressure on the wear glass.

But, that doesn’t matter much to me. These headphones are still very comfortable than many headphones I’ve owned before.

Over time, the headband loosened and the padding contracted to adjust to the shape of the head.

The wearing comfort would scale up by the time. And you will be able to wear them for hours without feeling any fatigue. Thanks to their major plastic construction.

The ear pad has dense foam wrapped in velour and is very soft against the skin. Some users’ ears may touch the inside of the pad, so it would be nice if the inside was a little wider.

Though there is enough clamping force, the only issue I have with it is it can be pretty vicious at the beginning.

But, it’s very easy to get rid of it by pulling the headband all the way out and slightly bending the extension.

Thus, the Sennheiser HD 660S has good wear comfort.

7. How Do Sennheiser HD 660 S Open Back Headphones Deliver Sound?

Sennheiser HD 660S are the top of list headphones. These open-back cans are all time favorite for me in HD 600 lineup.

So, how do they deliver in the sound department?

Well, the headphones for the music I listen to the most, it’s a luxury. I thoroughly enjoyed them. As usual, I also find a few flaws as no device can be perfect. So are they. The price tag seems on the higher side.

Now coming to the bass performance, I found it to be tight, fast, and punchy. Without EQ, the amount of bass tends to be too heavy. And this doesn’t suit heavy bass genres like contemporary hip-hop. Also, it’s not ideal for various electronic subgenres.

There’s still a fair amount of low-mid and high end. I listened to some instrumental/vocal-focused genres like rock, jazz, soul, and classical. For me, low-mid and high complemented very well to them.

EQ allows you to boost the bass quite a bit without distorting it or making it sound awful. Yes, I got the upper limit with a low-shelf filter of +12dB 100Hz and a preamp gain of -12dB. Very interesting!

There is enough amount of rumble and thickness. This is perfect for bass-heavy music. But, a little disappointment here is it bleeds a bit in the mids and pushes vocals back a lot. And there is also a bit of distortion in the sound.

I am very excited when the +5.5dB from the Harman EQ hits the sweet spot. In fact, I am quite impressed to see the bass extending into sub-bass. That too without hurting the midrange or showing signs of struggle or distortion.

At the end, HD 600 might not have all qualities to become a bass cannon. But, for my collection of favorite over ear headsets, it’s capable enough. It does deliver good sound.

8. Sennheiser HD 660 S Open Back Headphones Microphone and Call Quality Review

Sennheiser HD 660 S are open back over ear headphones. They don’t have a microphone. So, call quality test is not done.

9. How Do Sennheiser HD 660 S Open Back Headphones Perform in Gaming?

I have written a very comprehensive article on the best gaming headphones. Since I have Acer Nitro gaming laptop, I also wanted to try my Sennheiser HD 660 S for gaming.

After a couple of months with these headsets, these are now good gaming companions. Thus, I chose this topic worth mentioning. After all, the 660 S has also become my favorite gaming headphones.

I used a Steelseries Arctis 7. This was a great headset to use with games in its natural habitat. I found the technical prowess of the 660 S showed some obvious advantages.

For competitive shooters, I play Overwatch and occasionally CSGO. For both imaging is beneficial to see spatial awareness and understanding. This also lets me know what’s going on when there’s a lot going on at the same time.

I am able to hear better. Also tried the 660 S with games like The Witcher, Battlefield, and Forza Horizon 4. They sound better and more immersive on it. A wider soundstage might be desirable in a game like this.

So, my experience using these headphones with games is pretty good. I am sure, you should have a great experience. Give it a try now!

10. Sennheiser HD 660 S Open Back Headphones- Wireless and Bluetooth Review

Sennheiser HD 660 S are wired open back over ear headphones. They don’t have a Bluetooth or wireless feature. So, wireless or Bluetooth review is not done.

11. How Do Sennheiser HD 660 S Open Back Headphones Pair with Devices?

Sennheiser HD 660 S are wired headphones with no wireless or Bluetooth connectivity. Thus, pairing or connecting these headphones is via included cable.

12. Sennheiser HD 660 S Open Back Headphones- Noise Cancelling and ANC review

Sennheiser HD 660 S are passive open back over ear headphones. They don’t have any active components. They don’t block noise and neither have ANC features.

13. Control and Portability- Sennheiser HD 660 S Open Back Headphones

These are wire open back headphones and don’t have those controls as the headsets with the app have. The connectivity of the Sennheiser HD 660 S is through TRS cable.

In terms of portability, these headphones are very large. You can’t fold them more compactly and the cup won’t lie flat.

They also don’t offer a dedicated case or pouch for carrying the headphones. This is a bit of a disappointment for me. But you shouldn’t carry open-back headphones often.

14. Sennheiser HD 660 S Open Back Headphones- Frequency Response

The Sennheiser HD 660S over ear headphones have a very good frequency response. I am impressed it’s consistent.

The open back and ear pad design let these headphones offer near-perfect consistency when it comes to reproducing bass.

The maximum deviation across the bass range was less than 1 dB. But, variations in the high frequency tend to occur.

And depending on the mounting position and the shape of the ear, a maximum high frequency deviation of 7 dB is conspicuous.

15. Sennheiser HD 660 S Open Back Headphones Audiophile- Review

The Sennheiser HD 600 and Sennheiser HD 660 S over ear headphones are more or less the same. But, when it comes to audiophiles, the HD 600 is a better choice.

Most likely audiophiles prefer a more neutral sound profile. The bass and midrange responses are about the same.

But the HD 600 has brighter, more present highs, and the HD 660 S is more muffled. The HD 660 S’s modest treble may be a good fit if your high end tones are particularly shrill or painful.

But for most people, the HD 600 has a more balanced sound overall.

  • Excellent sound reproduction
  • Very comfortable for long listening sessions
  • Very good design
  • Replaceable cables
  • Pricy as compared to low end earphones
  • Sound leakage by design
  • Extremely low noise isolation

Conclusion: Helping You Make Informed Decision Easy

The HD 660 S over ear headphones do an excellent job in many things. I didn’t see major weaknesses in most of its components.

After more than six months of extensive use, it feels like there aren’t many headphones in this category.

I would like to use them for my daily driver. The combination of comfort, a well balanced sound signature never gets boring.

The resolution and the flexibility to apply EQ to different sound signatures is very good. That makes these headphones very difficult to criticize.

Frequently Asked Questions (FAQs): Things You Must Know Before Buying

A: The Sennheiser HD 660 S is renowned for its exceptional audio quality and comfortable design, making it a popular choice among audiophiles and music enthusiasts.

A: While the HD 660 S can be used without an amplifier, using a dedicated headphone amplifier can enhance its performance and provide a better audio experience, especially with high-quality sources.

A: The HD 660 S features improved drivers and a refined sound signature compared to its predecessors, delivering more accurate sound reproduction and better clarity across the frequency range.

A: Yes, the HD 660 S is suitable for gaming and movie watching due to its accurate sound positioning and detailed audio, which can enhance your immersion and overall experience.

A: Yes, the HD 660 S comes with replaceable ear pads. To maintain the headphones, clean them gently with a soft, damp cloth, and consider replacing the ear pads over time for continued comfort and hygiene.


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