We’ve long been fond of Sennheiser’s HD 600 range of open-back headphones, which have been impressing us since the late ’90s all the way through to current incarnations, for their wonderfully comfortable design and smooth, very listenable performance.

It’s quite a departure then, for the HD 600 range to introduce a closed-back design, but that’s exactly what the Sennheiser HD 620S headphones are. Sennheiser aims for the new HD 620S headphones to have the airy spaciousness of an open-back design with the privacy and non-leaky advantages of closed-back cans. Does it succeed?

Price

The Sennheiser HD 620S wired headphones cost £300 / $350 / AU$650 at launch, remaining firmly in the HD 600 range’s long-standing tradition of being not-too-budget and not-too-premium, attracting casual listeners and audiophiles alike.

At this price, there are plenty of solid five-star headphones we like that are of an open-back design, such as the Grado SR325x and Beyerdynamic Amiron, and Sennheiser’s own HD 600 cans. The closed-back headphones we rate highly at this price include the comfortable and punchy, articulate Beyerdynamic DT 700 Pro X headphones (tested at £219 / $299 / AU$369).

Build & comfort

Sennheiser’s HD 600 range has always valued comfort for long listening periods, so we have certain expectations of the HD 620S. The build quality is solid: the frame does feel a touch plasticky, but the reinforced metal in the headband and earcup housings make the whole arrangement feel sturdy and there are no creaks when we twist and bend the headband. The HD 620S headphones share design cues with the more budget HD 560S cans, but the new closed-backs have a speckled, textured finish on the earcups to distinguish themselves from their open-back brethren. 

There is decent cushioning on the headband and even more padding on the earpads, but some of us on the review team found the clamping pressure a bit too firm on these headphones. While listening for longer periods will loosen the structure over time, those on our review team – who normally complain about headphones not feeling snug enough – found there were undue pressure points at the side of the head. Other reviewers didn’t find this a problem, though, so the fit may vary. This is something we’ve encountered with Sennheiser headphones before, and it’s something to be aware of if you wear glasses or plan on listening for long hours. 

Adjusting the headband is easily done and the earcups swivel just enough – not too much, mind you – to encompass your ears fully and make a good seal. There is ample space inside the earcups, but our ears did get warm after a couple of hours of listening. 

In comparison, the Beyerdynamic DT 700 Pro X is a far more comfortable pair with instant long-term appeal, thanks to plush, pillow-soft velour earpads and a secure but lightweight design with no undue pressure anywhere; it’s easy to forget you’re even wearing them. You certainly won’t forget you’re wearing the HD 620S headphones.

There are some lovely details with the HD 620S’ design, though. Three raised dots under the left-side hinge are there to guide you towards the correct orientation. The included 1.8m cable is detachable; it twists and locks into place in the left earcup, keeping it secure and making it easy to replace with other cables if you want in-line mic controls or different lengths. The supplied cable has a 3.5mm connector with a 6.3mm adapter. A balanced 4.4mm cable option will be available later this summer.

The HD 620S don’t fold up or fold flat, which can make them a bit cumbersome to carry if you want to take them on your daily commute, but you do get a soft carry pouch to keep your cans protected. 

Sound

The HD 620S feature custom-tuned 42mm drivers, and the angled baffles are designed to improve airflow and mimic the spacious sonic character of an open-backed pair, without that “boxy” quality you normally get with closed-back designs. The stainless steel plate in the earcup covers further helps with isolation and manages internal reflections to keep the sound signal as pure as possible.

The aim here is to deliver an open sound, while also keeping you isolated from the outside world and prevent any sound leakages (and to keep the outside world isolated from your music tastes, naturally). In that objective, the HD 620S are a success.

We test the Sennheisers in a variety of set-ups during our listening period. Our main source was Tidal Hi-res on a MacBook Pro, and we swapped between using the Cambridge Audio DacMagic 200M and Chord Mojo 2 DACs. We also plugged the cans directly into the MacBook’s 3.5mm headphone port and used them with the more premium Naim Uniti Atom Headphone Edition streamer/headphone amp. In general, we would avoid pairing the HD 620S with any overly forward or bright-sounding kit, as that can introduce a slight hard edge to the sound.

Compared with traditional closed-backs, the HD 620S certainly offer an airy and spacious sound. Waxahatchee’s Right Back To It fills an ample playground with ease and voices sound detailed and natural without being upfront – there’s a relaxed, easy-going quality in the HD 620S that we’ve long loved about this series of Sennheiser headphones. They’re pleasant to listen to.

These headphones invite you to simply sit back and enjoy the detailed and smooth sound, no matter what genre you’re listening to. While you don’t get bone-thudding basslines, there’s enough in the way of grip to enjoy listening to Run The Jewels’ Close Your Eyes and Massive Attack’s Paradise Circus. Rhythmically, songs flow with just enough snap and fluidity, and the leading edges of notes are clean and clear. 

There’s less fatigue when listening than you would normally get with the more upfront, closed-in nature of rival closed-backs, and the balance is fairly even. These aren’t precision tools, but the headphones are subtle enough to convey the laid-back sullenness of Wet Leg’s Chaise Longue as well as the heavier vocals of Slipknot’s Duality.

We would like a touch more excitement and punch when it comes to dynamics, though. The Sennheisers are a fairly undemanding listen, which shouldn’t be confused with boring by any means. But switching to the Beyerdynamic DT 700 Pro X gives us an instant uplift in energy and expression. You get the more muscular punch and slam of a traditional closed-back design, and the dynamics ebb and flow with greater conviction and propulsion. Listening to Eminem’s Godzilla, we hear the varying intensities of his quick-fire rapping and the propulsive rhythms come through more faithfully with the Beyerdynamics.

Of course, the trade-off is that you lose out on that lovely airy openness that the HD620S deliver, and it’s a less laid-back listen.

Verdict

The Sennheisers have nicely judged the balance of the HD 620S, and being able to offer the airy advantages of open-backs in a closed-back design is no mean feat. Despite our desire for more gripping dynamics, we find ourselves enjoying the wonderfully open, smooth and easy-listening approach of the HD620S.

For those looking for this specific sonic signature and design, the HD 620S are worth serious consideration. Just watch out for that clamp force and try out a pair before buying, if possible. 

SCORES

• Sound 4
• Build 4
• Comfort 4

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