Sennheiser HD 660S2 Review – Engrossing Audiophile Sound

The original Sennheiser HD 660S was an excellent addition to the Sennheiser open-back headphone family that was well-suited for studio work. But the latest iteration of these excellent headphones heads in a slightly different direction. In this review, we take a closer look at these new headphones and give you all the info you need to determine if they are right for you.

The Sennheiser HD 660S2 features a richer and more dynamic sound than its predecessor but at the cost of balance and neutrality. Despite the shift, they are still a fantastic pair of studio cans but are also now an enticing option for audiophile listening.

Features

Sennheiser returned to the drawing board with the latest version of the popular HD 660S. But while some elements have changed, much of what made the original popular remains. Let’s take a closer look.

Sound Quality 

The Sennheiser HD 660S2 features an engaging and dynamic sound profile that is noticeably different from the original model. While the original focused on supreme accuracy for a studio setting, this model drifts heavily toward an audiophile-centric profile.

The most significant improvement is the more profound and fleshed-out low-end response. Bass tonality is more decadent and offers greater depth and punch while retaining a decent level of neutrality.

The mid-range sees minor changes and for good reason. The original offered an impressive mid-range that was a delight to listen to. That remains with the HD 660S2 and is still the defining feature of the sound profile of these cans. Sublime performance from a company with an excellent reputation in the headphone market.

The highs are a little tighter than the original but are less precise than some studio-centric headphones. At first, I wasn’t 100% sold on the top end, but after countless hours listening to a variety of music, I could see what Sennheiser was going for. It’s a fatigue-free listening experience that retains enough accuracy to be a valuable tool in the studio.

Excellent in a studio setting and casual listening applications.

With a frequency response of 8Hz-41.5kHz, these headphones offer scope to deliver sound and reach much higher than many other studio and audiophile headphones. Maximum SPL remains the same at 104dB. Ample headroom for a studio setting or for blasting your favorite recordings. Total Harmonic Distortion also remains nice and low at <0.004%. High accuracy even when pushed to its limits. 

But it’s not all good news. Like the original, the HD 660S doesn’t offer the best soundstage experience. It’s noticeably improved but still falls short compared to other options on the market, including some other headphones in the Sennheiser line-up.

Despite this, the overall experience is excellent. The heavy marketing emphasis on audiophile sound is warranted, and I can see music lovers enjoying the sound profile.

It’s also impressive that with this shift, they have retained enough accuracy to maintain these headphones’ status as a viable option for a studio setting. Updating a popular set of cans is difficult, but Sennheiser has nailed it.

Comfort 

The Sennheiser HD 660S2 doesn’t stray far from the original in this area. These are comfortable headphones, albeit with one minor caveat.

The ear cup padding is superb. It’s plush and engulfing with a comfortable velour material that blankets the side of your head. Sennheiser has an excellent track record for comfortable ear padding, and I would easily place these headphones up there as among the best.

The excellent padding extends to the headband with ample give to help adapt to your head shape. Since I do shave my head, I’m acutely aware of any pressure on my scalp, and these displayed no annoying contact points.

My only gripe with these is the clamping force. These have a firm grip that might be a little excessive for some people. It’s not vice-like but certainly noticeable over longer listening sessions, and it might prove problematic for people that wear glasses.

Ultra-comfortable ear padding.

In one regard, this does offer improved stability which I appreciate. If I was looking at DJ headphones, stability is high on my list of essential features. But with open-back headphones, I’m in the studio or casually listening to music. In these scenarios, stability usually is not a huge concern.

These headphones offer a primarily plastic construction which helps keep the weight nice and low at just 0.57 lbs. (260 grams). If you are familiar with audiophile-focused headphones, you’ll instantly recognize how light these headphones feel, which adds to the overall comfort level of these cans.

As expected, the open-back design ensures ample airflow to keep your ears cool. It’s a defining feature of open-back headphones and a big part of why I like to wear them when listening to music over extended periods.

So while the clamping force is a little firm for my tastes, the rest of the elements more than compensate for it. It’s a holistic approach that ensures that most people will find these to be exceptionally comfortable.

Design 

The Sennheiser HD 660S2 looks like many other Sennheiser headphones, so whether you like the appearance of these will likely depend on your general thoughts about this shape style.

The first thing that stands out is the large earcups that dominate the side of your head but feature an attractive steel grille that protects the driver. The dominant black frame offers a professional appearance, but unlike the original, this model features bronze accents.

I’ve seen the use of bronze as an accent color increase across all types of music gear. I like this shift away from gold and silver. It’s classy without trying too hard to be showy and invokes a feeling of sophistication.

Expertly crafted components in an attractive frame.

Beyond appearance, the most significant difference from the original is a jump to 300 ohms impedance. These headphones demand an amp to get the most out of them. While you can still connect these directly to lower-powered devices like smartphones, the performance will suffer. The original was a lot more forgiving in that regard.

The Y cable design makes a return with Sennheiser connecting pins. I don’t mind this connection style as it allows the cable to rest in the middle of your body. But depending on your setup, you might find that the cable gets in the way.

These headphones don’t collapse into a smaller profile. There is a pouch in the box, but it is mainly for day-to-day protection and storage at home. These are not the most travel-friendly cans.

The open-back design leaks sound and won’t provide any isolation. This is by design, so if you need either of those features, you’ll need to look at closed-back alternatives. Sennheiser offers an excellent range of closed-back cans, so if you want to stick within the Sennheiser eco-system, you’ll have plenty of options to choose from.

Durability 

Despite a predominantly plastic build, the Sennheiser HD660S2 is surprisingly very durable. The plastic is thick and doesn’t creak excessively. The headband features a thin metal strip that offers enough flexibility to adapt to your head shape.

While they are durable, they are also lightweight, and I would still recommend taking care of them. They are plastic, and considering the price tag, the last thing you want is to see these shatter from an aggressive fall.

High-quality construction from a brand you can trust.

The internal components are superb, with an ultra-light aluminum voice coil with excellent impulse response. The quality extends to the ear padding, which is replaceable. The quality of the cables is also exceptional.

These high-quality cans feature precision German design from a company with a long history in the audio scene. While they do feature German engineering, the construction takes place in Ireland. Solid cans that will last for years if treated well.

Value 

The value proposition of the Sennheiser HD 660S2 headphones is not the most convincing. In one regard, audiophile headphones can rapidly stretch well beyond this price point, but there are also affordable alternatives that are more than capable.

The HD 660S2 comes with a good range of accessories.

I am happy to see that Sennheiser now includes a pouch. It’s not the best pouch in the world but still more than what the original offered. You’ll also have the choice of two cables and an adapter inside the box.

Are these a little overpriced? Perhaps, but you get a sensational set of headphones that sound great, offer high build quality, and have a profile that can tackle audiophile listening and studio work. While not budget-friendly, these are a worthwhile choice if you like Sennheiser headphones.

Customer Reviews

These headphones caused quite a stir upon release based on the excellent reputation of the original, and that hype was warranted. These headphones consistently score 4 and 5-star customer reviews, and industry experts have also rated these headphones highly. I do not doubt that these will continue to be a go-to recommendation.

For The Love Of Music

The term audiophile gets thrown about a lot, and while some might consider segments of the community a little elitist, every person who identifies as an audiophile will have one thing in common—a complete love for music.

Whether you listen to intricate jazz recordings, faun over a legendary classical composition, or love the dynamic features of modern quality produced rock, pop, and electronic music, you deserve to have headphones that give you the absolute best listening experience.

If you love music, you deserve high-quality headphones.

Headphones are a significant investment, especially high-quality cans like the Sennheiser HD 660S2. But the experience is incomparable, and if you love discovering the often hidden details within quality-produced recordings, they become almost essential.

There is one final thing I’d like to highlight. High-quality cans are an excellent investment, but no matter how good the headphones are, if the source material is poor quality, you’ll have a subpar experience.

Seek out the highest-quality version of the music you love—ideally, lossless audio formats like WAV or FLAC. But also consider the quality of the production itself. Expertly mixed and mastered music can be an experience in and of itself compared to poorly produced music.

Combine premium headphones with high-quality music, and you’ll likely find an even deeper appreciation of the music that has shaped your life.

Other Options

Open-back headphones have become a staple for mixing and mastering and an excellent choice for casual listening (as long as you don’t need isolation). There are multiple exceptional options out there. Below we take a quick look at some compelling alternatives worth exploring.

Shure SRH1840 Review

The Shure SRH1840 mastering headphones are perfect for studio work. They offer a detailed and natural sound profile and come in at a lower price point.

• Neutral sound profile that is excellent for critical listening.
• Dependable construction with a high comfort level.
• The clinical sound isn’t the best for an audiophile listening experience.

AKG K702 Review

I’ll be the first to admit that the price tag of the HD 660S2 might be beyond what some might want to pay. In that case, the AKG K702 is a reasonably priced alternative.

• Superb definition in the midrange and highs.
• Excellent soundstage and spatial placement.
• The bass response is underwhelming and a little lifeless.

Neumann NDH 30 Review

One of the leading alternatives to the HD 660S2 is the Neumann NDH 30. These open-back headphones offer pure, clean sound along with rock-solid build quality.

• Revealing sound profile that is ideal for serious studio work.
• High-quality components and a collapsible design.
• Much like the HD 660S2, these are not budget-friendly.

Should You Buy?

It isn’t an easy task to update a set of headphones that have already proven to be successful, but Sennheiser has done an excellent job of refining the HD660S2 to further lean into its audiophile roots.

These are dynamic headphones that are a joy to use. The high comfort level and premium components make it among the best open-back choices on the market. The slightly updated styling is also a positive move. Many people often complain about the lack of bass definition from open-back cans, so it’s great to see a company tackle this challenge head-first and succeed.

If you are on the hunt for a high-quality pair of cans that are equally great for casual listening as they are in a studio setting, the HD 660S2 is an excellent choice.