Sennheiser HD 620S Headphones Review

The Sennheiser HD 620S are closed-back headphones that share aesthetic similarities to open-back headphones like the Sennheiser HD 560S and the Sennheiser HD 598. These have non-articulating oval ear cups and thick faux leather padding along the center of the headband and ear pads. The sliding headband glints with sections of silvery metal on an otherwise black plastic construction. Their straight cable is removable and terminates down the left side. Available in a single monochromatic black, the manufacturer's logo is placed on the outside of each ear cup, and the name is written along the top of the headband.

The Sennheiser HD 620S feel very comfortable. Their faux leather padding is generous around the ears where the headband meets your crown, and the headband distributes their weight well. Whether you have a larger or smaller head, the headband offers a good extension range. The clamping force is high, though, quite similar to other popular closed-backs, like the tight-fitting Beyerdynamic DT 770 PRO. While this compression should help these cans form a good seal on your head, the overall size of the ear cups makes it harder to get a reliable seal, particularly at the bottom of the ear cups. Wearing glasses can also make getting a good seal over your ears difficult, as the arms interrupt the seal, impacting their sound. On the upside, the ear cups are deep enough to accommodate most people's ears.

These headphones aren't very portable. They don't fold down any smaller, and the ear cups can't rotate to lay flat. You can remove their cable to make them easier to carry, but otherwise, they're pretty large, and you'll need real estate in your bag to tote them around.

Their carrying pouch is middling. It's made of thin fabric with a drawstring to close the pouch. Besides preventing your headphones from collecting dust, it doesn't do much. It won't cushion a fall or protect the headphones from water spills.

The Sennheiser HD 620S are well-built. Their housings are mainly plastic with aluminum, reinforcing the headband, and they're amply padded. Their removable cable is good, too, covered in para-aramid, which feels sturdy. However, they're a bit stiff to adjust. Unlike the thicker covering over the drivers on the Sennheiser HD 598, there's not much of a buffer protecting the drivers from getting pierced or damaged, as you can see here.

They're stable-fitting headphones. Due in part to their high clamping force, they'll stay on your head when you nod along to music. That said, if your head nods get really energetic, the headband can slide down, requiring a readjustment.

• Sennheiser HD 620S headphones
• 1/8" TRS to 1/16" TRRS cable (6.07 ft / 1.85 m)
• 1/8" TRS to 1/4" TRS audio adapter
• Drawstring pouch
• Warranty booklet

The Sennheiser HD 620S have a sound profile that boosts select bass frequencies more than the Sennheiser HD 600, their open-backed sibling, though not evenly. This tuning produces a much more obvious boom and injects more thud to kick drums. Deep sub-bass in EDM tracks is still subdued in the mix, though. There's a dip de-emphasizing the low mids, so the harmonics of bass strings are weakened, while the rest of the mids sound relatively balanced in the mix for reasonably clear melodic keys and human speech. The treble trends towards broadly clear and bright, but it's also hampered by narrow dips and peaks, which can render your favorite diva's vocals a bit harsh, clear, or dulled in the details, depending on the pitch.

These output a good amount of bass, but largely due to their inconsistent frequency response (which you can see in the next test), bass frequencies take a massive hit when the headphones are worn by different people, which is an important consideration.

The Sennheiser HD 620S have sub-par frequency response consistency. Their ability to deliver consistent bass and treble is strongly impacted by their large ear cups, which often don't seal around your ear perfectly. Their soft ear pads, combined with the tight clamping force, can easily cause the seal to break because the padding doesn't always sit evenly, so you have to place them with care. If you have a small head, a gap can form at the bottom of the ear cup that diminishes bass.

Similarly, if you wear glasses, these can break the headphones' seal and dramatically reduce the bass, too. For example, the graph plots for 'Test 2' and 'Test 3' (above) represent the same person with glasses on ('Test 2') and glasses off ('Test 3'), and you can see how that single isolated variable significantly alters their bass consistency. Unlike the Sennheiser HD 490 PRO, these don't include ear pads that have specialty ridges to accommodate glasses' arms without compromising the seal.

Their bass profile's target compliance is excellent. They reproduce a laid-back amount of rumble through the low bass and part of the mid-bass. A notable boost to the mid-bass and part of the high-bass adds a significant amount of punch and body to basslines in songs like The Night by Frankie Valli and the Four Seasons. However, the dip in the upper bass frequencies clears up muddiness, which carries on into the mid-range.

Their mid-range target compliance is great. A slight de-emphasis in the low-mids can reduce the depth of lead instruments a bit. Otherwise, the headphones convey lead and melodic instruments evenly for the most part. The minor underemphasis can weaken vocals in the upper mids slightly, but otherwise, keys and guitars sound full.

Their treble's target compliance is good. Most of the range approaches the target for a bright voicing that's largely representative of your audio. However, the range is somewhat uneven, reproducing vocals with a bit of harshness in the low-treble or weakened intelligibility, depending on the pitch. Sibilant sounds like Ss and Ts in vocals, and cymbal hits are alternately dull and slightly piercing.

Their peaks and dips performance is decent. The headphones follow their own sound profile somewhat well. A small bump in the mid-bass injects a bit of body to the bass. A minor dip from the high bass into the low mid reduces boominess and clutter from thick rhythm guitars. Through the rest of the mids, a series of bumps and narrow dips mostly add focus to vocals and melodic instruments, but these are rather small. In the treble range, a narrow peak adds harshness to vocals, and it's followed by an uneven couple of dips, which dulls and hollows out the detail and articulation of voices and cymbal hits somewhat. The tall peak in the mid-treble adds sharpness and can make sibilant sounds like Ss and Ts sound a little painfully bright.

The Sennheiser HD 620S have good imaging performance overall. Most of the products we've tested by the manufacturer demonstrate good ergonomics and solid quality control, so these results align with that. Their group delay is below the audibility threshold, resulting in tight bass and transparent treble. Similarly, their amplitude is well-matched. Frequency mismatch is okay, but it's the phase mismatch where their imaging struggles. The stereo image shifts to favor the right driver in most of the bass range, particularly the mid- and high-bass frequencies, and the soundstage is affected by this phase mismatch, giving the impression of it closing inward on the left side. Imaging varies between units, so these results are only valid for our unit.

The Sennheiser HD 620S have a disappointing passive soundstage. While that's pretty normal for closed-back over-ears, the manufacturer advertises that these have a wider and more spacious soundstage than most closed-backs. Compared to open-backs, these sound less open (unsurprisingly) and don't interact much with your environment, causing your audio to still sound like it's coming from inside your head. That said, they interact with your outer ears somewhat, so their soundstage will sound wider than in-ear headphones, for example, but these don't have an open-back level soundstage.

These over-ears have good weighted harmonic distortion. It's low enough that your audio remains pure and clean throughout the frequencies. The handful of peaks in the low-bass and the low-treble, while elevated, are so narrow that they won't impact your audio's quality.

These are the settings used to test these headphones. Our results are only valid when used in this configuration.

The Sennheiser HD 620S have middling full-range noise isolation. As with most closed-back headphones that passively isolate you from external sounds, they have a much stronger impact on trebly sounds than lower frequencies; sudden and bright clinking sounds in your office kitchen are tamped down effectively. However, you'll still hear folks talking. Rumbling construction noise outside your window will reach you, too.

These headphones struggle to create an isolating seal with the glasses' arms. Because an unbroken over-ear seal is essential for optimizing isolation, you'll experience less effective noise isolation performance if you wear glasses.

You'll note the small bump in the bass region, and this appears to be unique to the headphones interacting with the testing rig and, importantly, not something you'll experience.

These have poor noise isolation in common scenarios. That's expected from headphones with passive-only isolation, which most effectively blocks high-pitched noises. For instance, if you're on an airplane, the lower mid-range and bassier ambient din can still reach your ears. In an office, your coworkers will get muffled somewhat, but not very effectively.

As mentioned in Noise Isolation - Full Range, the small bump in the bass region is not something you'll experience when you wear the headphones.

Their leakage performance is fair. What escapes is pretty even in volume across the mids and treble range, and sounds like vocals, lead instruments, snares, and cymbals are audible to those nearby in your household. Bass leaks, too, but not as noticeably. Because the headphones are closed-backs, they don't leak as much of your audio as open-backs, like the Sennheiser HD 560S.

The Sennheiser HD 620S are passive headphones with low latency. You can adequately drive them with most audio sources, like laptops, so they don't need a headphone amp. They include a para-aramid covered 6-foot cable that connects via its twist-and-locking 1/16" TRRS jack to the left ear cup, unlike the Sennheiser HD 490 PRO (aimed at audio professionals), which has separate wires going to each ear cup. The twist-and-lock design is secure, but it might be a pain if you need to find a replacement. You can also upgrade the package by opting for the manufacturer's balanced cable, which is available separately. The other end of the cable is a 1/8" headphone jack. You also get a 1/8" to 1/4" adapter.

Most PCs can sufficiently drive these headphones via their analog connection to your PC's headphone jack.

These headphones support audio only via their analog cable when connected to your PlayStation's controller.

You can plug the headphones into your Xbox controller's headphone jack for audio support only.