Disclosure: The HD 620S was provided by Sennheiser for the purpose of this review. Please read more about our product review disclosure here.

In the world of high-fidelity audio, the Sennheiser HD 600 open-back headphones have stood the test of time, remaining a favorite among audiophiles and audio enthusiasts for their exceptional sound quality and durable construction. Now we have what Sennheiser hopes will be the closed-back equivalent, the Sennheiser HD 620S.

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Overview

The Sennheiser HD 620S carries DNA from both the 500 and 600 series. Visually it looks similar to the HD 569, another closed-back headphone in the Sennheiser lineup. Internally, though, the driver has more in common with the HD 600 and HD 660S2. Given that Sennheiser has named this the HD 620S, that would indicate that not only does Sennheiser consider this to be superior to the 500 series, but also specifically the HD 600 (the HD 620S is directly compared to the HD 600 in their marketing material as well). So, does the HD 620S deliver on this? Read on to find out.

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Design & Comfort

In The Box

• HD 620S
• 1.8m cable (2.5mm to 3.5mm)
• 3.5mm to 6.3mm adapter
• Carrying bag
• Manual

External Design

As previously mentioned, the Sennheiser HD 620S has many visual similarities with the 500 series, specifically the HD 569. The cup and headband design overall are similar, but there are some key differences here.’

First, the headband padding and support have been upgraded. The HD 620S features cushy headband padding with a similar design (though different material) to the 600 series. As well, the headband slider mechanism is reinforced with metal, giving it a stiffer yet still satisfying feel and smooth operation. Aesthetically it looks miles better than the 500 series.

Secondly, the earcup’s look and texture have changed. We now have a more understated look, with the speckling on the side of the cups giving a sophisticated yet bold feeling to the headphones. I’m a fan of this design, I think it makes the HD 620S look extremely distinctive from anything in the 500 series giving it its own identity.

The HD 620S features a single 2.5mm connection on the left earcup. Also, on the left side where the headband connects to the earcup, are three braille-like dots to help you know which is the left side.

The headphones feel very solidly built. There’s no creaking or cracking, and the materials look and feel high quality.

Internal Design

Like all headphones in the 600 series, the drivers for the HD 620S are made in Ireland (the headphones are assembled in China). Yes they, are the same drivers found in the 600 series, though Sennheiser says they are custom-tuned due to the closed-back design of the HD 620S. The surround inside the earcup has been adopted from the HD 660S2 to give the headphones deeper bass without sacrificing clarity. It really seems like Sennheiser has taken the strengths of some of its best headphones to allow the HD 620S to compete with its open-back brothers.

As well, the HD 620S is wired for use with a balanced cable. Sennheiser will be selling a balanced cable that’s compatible with the HD 620S at a later date. They will also be selling a cable with an in-line mic for portable use.

Comfort

The headband padding has a leather look but a plastic feel and seems to be filled with foam. The headband mechanism extends quite a bit, meaning the headphones should fit most head sizes. The earcups have some tilt to them, but they are meant to sit flush against the side of your head to create a solid seal so the range of motion for them isn’t huge.

The earcup pads are synthetic leather, and have a solid depth to them. This is needed as the HD 620S uses clamping force to get a solid seal around your ears. Sennheiser headphones in general do tend to have a higher clamping force than most headphones, and since a solid seal is required to get the best sound out of these closed-backs I’d highly suggest trying a pair on before buying, which you should try do with any headphones you plan on purchasing.

The earcups have plenty of space inside so they should fit most ears. After a couple of hours of listening it does start to feel a bit warm, but there seems to be some ventilation going on as it never got too bad. This is usually one of the downsides of closed-back headphones, but Sennheiser seems to have made some good design choices to help mitigate it.

For myself, I found the HD 620S initially a little tight, but after a few days of use the clamping force lessened and the fit and comfort were just fine. The headphones stay solidly on your head while moving, so they are comfortable for both at home and on the go listening. I do wear glasses, but never found them to interfere with comfort or the seal of the headphones.

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Features

Portability

The Sennheiser HD 620S has a few things going for that make it a portable hi-fi headphone. First, with an impedance of 150 ohms and sound pressure level (SPL) of 110 dB, these headphones are not hard to drive. You will have volume issues using them with ultra-low power outputs (some older smartphones and laptops are like this), but generally most devices, even using something like an Apple dongle DAC, will drive these just fine.

To give you an idea of what to expect, I connected the HD 620S to the following devices using either their built-in 3.5mm connection, or an Apple USB-C dongle DAC. They had no issues with loudness nor issues with sound quality:

• Galaxy Z Fold 5
• Pixel 6
• iPhone XS
• Sony NW-WM1AM2
• Surface Laptop 4
• Razer Blade 15 laptop

Second, being closed-back headphones, they passively block outside noise. The HD 620S has been designed in such a way though that they seem to block even more outside noise than most closed-back headphones I’ve tried. I had no issues listening to them in a coffee shop or sitting in a park, they do an excellent job of blocking outside noise, even without any music playing.

Accessories

The HD 620S comes with a fairly standard 2.5mm to 3.5mm Sennheiser cable, a 3.5mm to 6.3mm adapter, and a carrying bag. Sennheiser has said that they will be releasing a balanced 2.5mm to 4.4mm cable in the coming months, as well as a 2.5mm to 3.5mm cable with an inline mic, making it even more ideal for portable use.

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Sound Quality

The Sennheiser HD 620 has many of the same characteristics as the 600 series. Tonality is neutral, and the overall sound is smooth. The imaging is excellent as one would expect from these drivers. You feel as if you are right there with the music in front of you, while simultaneously being surrounded by it. The soundstage quite wide for a closed-back headphone and gives a spatial quality to the audio you are listening to, especially for classical music and music mastered for Dolby Atmos/Sony 360. This goes in hand with excellent detail retrieval, allowing you to pick out individual instruments and their positions.

I found the HD 620S to scale fairly well with DAC/Amps. Using a simple dongle DAC will be just fine, but I noticed when using a higher end portable or desktop DAC/Amp, I was able to get more defined bass and slightly cleaner mids.

Bass

The extension to the sub-bass is excellent, assuming your earcup seal is good. There’s good bass impact without being too elevated or loose. I wouldn’t describe it as tight, but it’s very satisfying and retains good detail. If you’re looking for bass that hits you these headphones won’t do that, but there’s still enough there to keep you interested and the music dynamic.

Mids

The mids are neutral and lively with excellent clarity. There’s an openness to the midrange, and since there is no bass bleed you get a very clean sound with natural timbre, similar to other headphones in Sennheiser’s 600 series. The upper midrange is a bit forward, so vocals and guitar do stand out. There’s no harshness in the upper midrange either. Overall, the mid-range has good energy.

Treble

The treble has great clarity and detail, and an overall smoothness to it. I did find on some tracks the treble to be a bit peaky, or bright. Not like Beyerdynamic headphones, but it was very track-dependent. Overall though there is no sibilance, which suits me just fine. It’s not as warm as the 600 series, but there does seem to be more intimacy in the treble like it’s right there in front of you.

Gaming

The wide soundstage and excellent imaging detail make the HD 620S a natural fit for use as a gaming headphone. Using them for Call of Duty multiplayer I was able to easily hear footsteps and gunfire positions, helping me pick out enemy players. Switching over to games like Skyrim and Witcher 3, there’s excellent surround sound detail and immersion.

Overall, the sound profile of the HD 620 is neutral and clean, with excellent bass extension and detail. The headphones sound lively and are very open with excellent imaging and soundstage for a closed-back. The passive noise isolation helps give sort of a black background that brings out the audio even more, giving a feeling of intimacy with the music, all while having no sound leakage. The HD 620S is suitable for all music genres, with everything I threw at it sounding excellent.

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Comparisons

HD 569

The HD 569 has a fairly dull sound and can be rather piercing. Compared to the 600 series it has a very underwhelming sound profile. Thankfully, the HD 620S improves in every way and is vastly superior to it. If you have, or are considering the HD 569, then the HD 620S will be a massive upgrade.

HD 600

The HD 620S sounds very close to the HD 600, though the HD 620 improves on a couple of things. The bass response and extension are much better on the HD 620, whereas on the HD 600, the bass is fairly weak. The HD 600 has a more relaxed sound to it, whereas the HD 620 is more crisp with a bit better detail retrieval. If you currently have an HD 600 I wouldn’t say that the HD 620S is an upgrade, but it is better in some areas and is appropriate for different use cases. Overall though I prefer the HD 620S.

Beyerdynamic DT 770 Pro

Both the DT 770 Pro and HD 620S have excellent imaging, but the HD 620S has a slightly wider soundstage. As well, the bass extension of the HD 620S is more refined. The mids are fairly similar, but I would say more detailed in the HD 620S. The Treble, well, it’s definitely brighter on the DT 770 Pro. If sibilance is an issue, the HD 620S wins handily. Overall, the HD 620S sounds more musical and is better for enjoying music and other audio. The DT 770 Pro excels more as a studio headphone for monitoring.

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Final Thoughts

The Sennheiser HD 620S is not simply a closed-back version of the HD 600, even though Sennheiser’s own marketing material compares the two. The HD 620S carries many of the positive sound qualities of the 600 series such as the natural timber, neutral tonality, and smooth sound. At the same time, it offers improved bass extension, better imaging, and excellent noise isolation. With a price of $349, these are not in budget territory, but they are also not as expensive as many recently released headphones. For music enjoyment and even gaming use, I think the HD 620S provides excellent value and might be one of the best closed-back headphones under $500 right now.

The HD 620S is versatile enough to be the only headphones you need to buy, which will be an attractive proposition for many people, especially those just getting into the audiophile hobby. They’re comfortable, have a rich and satisfying sound, and the excellent passive noise isolation allows you to immerse yourself in your audio. I can safely recommend the HD 620S headphones, and I encourage you to try out a pair at your local audio store.

HiFi Oasis highly recommends the Sennheiser HD 620S.

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