Sennheiser HD 620S Review

Sennheiser HD 620S

 

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Sound – Sennheiser

In this chapter we always first look at how the bands are describing their unit’s sound signature. In the case of this HD 620S Sennheiser has the following to say:

Sennheiser’s HD 600 series has long been the standard for natural tone, thanks to our dedication to continuously improving the open-back concept. The 500 series introduced later offers a soundstage that immerses listeners in their music. The distinctive DNA combination of these two series lets the HD 620 excel where many closed headphones struggle, preserving the detailed, smooth sound the 600 series is known for.

Sennheiser HD 620S

Sennheiser describes the HD 620S as having a natural, detailed sound with a wide and spacious sound stage as well as tight and accurate bass response. In the picture below you can also see that Sennheiser likes comparing the HD 620S’ tuning to that of their iconic HD 600 headphone.

At the after show event we got the possibility to talk to Jermo Köhnke about Sennheiser’s audiophile products, and it was quite interesting to hear him confirm that Sennheiser in no way is looking at the Harman curve to tune their products. Anyway, let’s find out how the HD 620S sounds and compares, and what amplification is needed to really make it shine!

Sennheiser HD 620S

Sound – Performance

With its 150Ohm impedance and 105dB sensitivity, the HD 620S is the kind of headphone that likes to be hooked up to a dedicated headphone amplifier, or a more powerful portable player in order to sound its best. We’ll get back to the synergy part in a bit, but for all sound assessments we hooked up the HD 620S to dedicated amplifiers, both tube as well as solid state designs.

As you can see in the FR image, the HD 620S clearly shows a more v-shaped tuning, and that is clearly audible as well. But first things first. Sennheiser is focusing a lot on the open character of the HD 620S and it is one of its USPs. I am pleased to say that the HD 620S indeed sounds open and spacious for a closed-back headphone. That said, there are limits to its openness. You will still hear this is a closed-back headphone and you don’t get true open feeling you get with some of the closed-back flagship headphones such as the Stealth, HE-R10P and Caldera Closed. But in this price range, the performance in regards to openness is impressive. In fact you get an overall excellent performance when taking the HD 620S’price point into account.

Looking at the soundstage, we see that the HD 620S sounds wider than it does deep. The mids are nicely spacious and that helps with the soundstage impression, but depth and layering wise the HD 620S is not the strongest performer. But neither were the 6-series. In regards to overall precision the HD 620S is on par with what to expect at this price point, though I still place the 660 at a higher level. It’s just not as refined and precise or extended in notes. The same goes for the note decay.

Sennheiser HD 620S

Sennheisers’ second selling point is the bass performance. Bass is slightly elevated in this headphone, and then we are talking about the mid bass mostly. So you have more than neutral presence, but it is never exaggerated or too much and it is controlled bass. The sub bass presence is not as apparent (but more so compared to the 6-series). Bass always has good impact and it comes delivered with a nice punch, when properly amped. Bass is soft and smooth and carries a pleasant amount of warmth.

The HD 620S’mids are lighter in weight which is logic with the more v-shaped tuning. It’s not that the mids are thin, but on bad recordings the mids can suffer. The mids are spacious and airy, and have a soft, relaxed presentation. Sennheiser has also tuned in some nice vocal forwardness around the 3k mark. Almost everyone likes this energetic boost.

The HD 620S’ top end is safely tuned. It is very easy to listen to as it is soft on the ears but it doesn’t extend very far. There is enough precision, body and energy to keep things contrasting, exciting and engaging, and that’s what a v-shaped tuning is about.

Most of the body can be found in the lower regions and especially in the mid bass. In general the HD 620S has a natural and smooth presentation, with a hint of warmth. The HD 620S is soft on the ears and easy to like and listen to. General speed (PRaT) is average to good, but the separation is well-executed.

Except for with one super powerful headphone amplifier and another mainly speaker amp, the HD 620S was dead silent. The HD 620S offers a good level of clarity and cleanness, especially at this price level. Of course this isn’t a $3K headphone, so it can be even better.

TL;DR: The new Sennheiser HD 620S offers you a dynamic, engaging and musical sound with a softer and warmer feel to it. For a closed-back headphone, the open-back like presentation is impressive and it all sounds natural and smooth. It’s s safely tuned headphone, with an easy to like, enjoyable sound.

Sennheiser HD 620S

Sound – Suede Pads

For this section I am using the Aquarius R2R DAC and the ZMF Aegis tube amp (see later). Luckily I still have the HD 560S here so it was an easy switch to the Sennheiser velour pads. I’m not sure Sennheiser likes me trying on other pads, but I am sure some of you will do the exact same.

Sennheiser HD 620S

I can be very short on this, the suede pads don’t work well at all with the tuning of the HD 620S. Basically all weight and bass presence disappears and you get thin, lifeless sound. So save yourself the time and skip testing/trying this.

Sound – Sources / Amplification

It’s no secret that the higher impedance audiophile Sennheiser headphones really like OTL design tube amplifiers, but in this chapter we’ll compare the HD 620S’ performance on OTL, non-OTL as well as solid state amps. The selection of desktop amplifiers/sources is the following: LaFigaro 339, ZMF Aegis, Feliks Audio Euforia EVO, Hifiman Serenade, EarMen CH-AMP. For the portable section I have selected the Chord Mojo 2, Cayin RU7 and the SP3000.

Sennheiser HD 620S

Tubes

The LaFigaro 339 was the first tube amp I bought over a decade ago, and I got it especially for the Sennheiser HD 600, HD 650 and Beyerdynamic DT990 high-impedance headphones. If you are fan of high impedance headphones, than you really need to source a 339 from somewhere, as it is one of the very best amplifiers with high impedance cans. Especially if you have a soft spot for tube amps and tube sound. They’re not being built anymore and I regularly get requests to sell mine, but I never will. Anyway, let’s get back on track. With the 339 the HD 620S sounds soft and warm as you would expect. It is a very romantic, smoother and warmer sound with a nice overall fullness to it. Of course the V-shaped tuning is still present, but the 339 does make it sound a bit more balanced. You still get the nice, airy and open presentation with a bass impact that most of the younger consumers will highly appreciate. The HD 620S does sound a tad slower here but it makes up for that with pure musicality. The HD 620S is soft on the ears in this combo, and the vocals here are softer. The treble end is smoothened, easy on the ears and unoffensive at all times. If you like your Sennheiser headphone to sound smooth, warm, musical and easy on the ears then you can’t go wrong with this combo.

Sennheiser HD 620S

The ZMF Aegis amplifier is a transformer-coupled amplifier and it like the 339 is an incredible amplifier. The big difference here besides the technology, is that the Aegis can drive every single headphone on the market, it’s not just for high impedance headphones (and it offers multiple output settings for that). With the HD 620S I like using both the Medium as well as the high gain setting. In Medium gain you get a softer and warmer sound, while the dynamics and speed increase on the high setting. The HD 620S here sounds a bit more detailed and refined compared to with the 339, and the vocals carry a tad more energy. You get a good overall fulness with improved extension on all levels. The Aegis just is a better technical performing amp, and the HD 620S lets you hear that. Unless you want the ultimate tube goodness (339), the Aegis is one of the best tube amp I tried with the HD 620S. It’s a perfect blend of technical excellence and tube sweetness. Aegis’ review will be up in the near future.

Sennheiser HD 620S

With the OTL Feliks Audio Euforia EVO, the HD 620S sounds lighter in body, but even better in extension and that both in notes as well as top/bottom end. The dynamics are increased and you get a livelier, less tube-ish sounding Sennheiser headphone, even though the tube sound obviously still is present. The stereo imaging, depth and layering with the EVO also are the best out of the amps listed in this article so far. If pure technicalities, dynamics, speed and extension are more important to you than tube warmth, then the combo with the EVO probably is the one for you.

Personally I like the HD 620S on all of the above amplifiers and they all have their unique things they bring to the party. One things is sure, the HD 620S sounds excellent with all of these tube amps. I also tried the HD 620S on some super high-end amps such as the Auris Audio Headonia 300b and the Feliks Audio Envy, but I doubt that many will be looking into purchasing these combos. That said, the combos do sound incredibly good and the HD 620S scales up nicely with the amplifier it’s hooked up to.  

Sennheiser HD 620S

Solid State

Switching to solid state, the first amplifier we’re looking into is the EarMen CH-Amp. This is a fairly neutrally tuned amplifier and it is super popular in Asia. Here I like the HD 620S most in high gain, simply because of the better dynamics, bass punch and tightness and vocal naturalness. The HD 620 sounds musical, faster and has good bass weight at all times. The vocals here are more forward but as they are naturally soft, they nicely contrast the bigger bottom end. The top end is nice, but soft on the ears and not very extended. From a technical point of view the combo performs well, but it isn’t the best technical level as we experienced before with the EVO (and Headonia). It is a good and musical combo, musical and pleasant to the ears, with a good level of energy and a lighter overall presence. Strings sound spectacular here, as well as the sub bass performance.

The Hifiman or should I say GoldenWave Serenade DAC/AMP is of the better offerings in this price range. I really like the performance of the Serenade and it makes the HD 620 lighter but clean and clear. The vocals are naturally soft yet energetic, as is the top end. Vocals and the top end are lively and dynamic in this combo. The presentation is spacious and airy, but the extension of notes and sound stage isn’t on the same level as on the better tube amps. I would put it on the same technical level as the CH-Amp, which is pretty much the level of performance we can expect at this price point. It’s a good combo, just like with the CH-AMP, but it’s not as spectacular as on tubes.

The review continues on the third page. Click here or use the jumps below.

Page 1: Sennheiser, Sennheiser HD 620S, Specifications, Box & Accessories & Price, Design & Isolation & Comfort & Build Quality

Page 2: Sound Part 1, Synergy

Page 3: Sound Part 2, Synergy, Comparison, Conclusion, Summary

4.2/5 - (229 votes)
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Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.

4 Comments

  • Reply June 9, 2024

    Van

    Thanks for the review. Shouldn’t it be compared to the DT700 Pro pricewise? I’m interested in those differences.
    What can you say about it?

    • Reply June 9, 2024

      Lieven

      Nothing, as it isn’t available

  • Reply July 1, 2024

    Max

    Thank you for the review, Lieven!
    Didn’t understand what you meen by DT 700 Pro X are not available though?
    And I as well was expecting the comparison to Pro X model, rather than old 770s.

    • Reply July 1, 2024

      Lieven

      Thank you!
      I don’t have the DT 700 Pro X available here, it is not in my collection.
      The “old” model still is up for sale and probably there are more on the planet than the newer model, so imho the comparison makes a lot of sense 🙂

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