Sennheiser HD620S review

In this case, not breaking any new mould is a good thing since the HD620S provides ample passive noise isolation via its artificial leather earpads and a fit that focuses on a secure fit over all-day comfort. They’re built to last, indicating their semi-professional lineage and perhaps, even audience. Although largely plastic, the steel-reinforced headband and earcup covers add the requisite structural rigidity to avoid any resonance or premature wear and tear. Little details like the swappable twist and lock cable connector are borrowed from more expensive designs, enabling higher quality cables to be used. Adequate cushioning on the head bang and earcups do make them feel reasonably plush if not velour-level plush.

Three dots on the left ear-up help the visually impaired quickly identify the correct orientation and the only big omission here is the lack of any folding option. Neither the earcups fold flat, nor do they fold inwards to reduce travel footprint. This makes the carry pouch that is bundled the only way to carry these around and it’s not the most elegant. A potential downside for some would be its excessive clamp force that starts heating up or hurting (or both) the ears after extended periods of wear. And this could be anything from an hour onwards…

The long-ish 1.8m cable is terminated to a 3.5mm connector but a 6.3mm adapter is supplied in the box and a balanced cable is slated to arrive later this year as an option. Using an angled baffle to mount the 42mm driver allows the HD620S to sound more open with a wider soundstage than typical designs that fire straight into your ears. Though the actual useable diaphragm size is quoted as 38mm, the claimed frequency response is an astounding 6Hz-30kHz via the single driver system. Its 150ohm lightweight voice coil gives it the right characteristics to be powered by a smartphone and a dedicated headphone amplifier/DAC.

For our tests, we chose to run them with a MacBook Pro 16in (M2 Pro) using the 3.5mm connector and through a Chord Hugo TT2 DAC using the 6.3mm adapter. Of course, there were differences…

In the same vein as some of the best pro-level headphones, the first impression of HD620S is that of neutrality. Coming from a pair of ANC mainstream headphones, it takes a few minutes for your brain to compensate for the lack of artificial bass boost and even though Sennheiser’s graphs hint at a boost around the mid-bass region, for a Sony WH, Bose QC or AirPods Max user, these will be filed under the “boring” section.

But give them a few minutes and they are anything but! Boz Scaggs’ Thanks to You sounds clean, crisp and airy, much like on Sennheiser HD600’s. There is a sense of speed and agility to the sound on electronic tracks like Toure (Quebicle Remix) by Ali Farka Toure and it’s easy to keep pushing the volume up since there is no sense of distortion. Of course, the difference in presentation between the MacBook Pro, even with an Audioquest DragonFly DAC in the signal path and the Chord Hugo TT2 DAC was enough to discern the difference these headphones are capable of in terms of soundstage. The Chord Hugo TT2 just allowed the instruments to breathe more, with a lot more clarity on decay and faster impulses.

Even though, the one thing the 620S lacks undoubtedly is punchy dynamics. Trying out the latest banger by Hanumankind just didn’t evoke the emotion a bass-heavy headphone would, simply because of the production value of the track. The Sennheiser seemed to neutralise the potency of the song and made it sound more tame and timid.  So we know that their engineers have succeeded in making the 620S sound more open with a great stereo imaging but it does come at the cost of traditional strengths of closed-back headphones.

It’s a clear type of audiophile who would be interested in the Sennheiser HD620S - someone who values transparency and resolution over all else. They can highlight the differences between sources and file codecs so easily that they serve as amazing tools for reviewers, engineers and prosumers. But if your listening tastes include a lot of hip/hop, house and such, you may find them a little lightfooted.