Sennheiser HD 620S: Audiophile-grade closed-back headphones for music lovers and gamers

At the heart of the HD 620S is a custom-tuned 42mm dynamic transducer manufactured at Sennheiser's state-of-the-art transducer plant in Tullamore, County, Offaly.

Sennheiser HD 620S closed-back headphones. Picture: Sennheiser.

The prestigious German audio company Sennheiser has long been a staple in the industry, renowned for its precision engineering and high-quality sound. The firm has a plant in Tullamore, where it manufactures audiophile headphones, including one of the world's most expensive headphones, the Sennheiser HE-1. Thankfully, not all its headphones cost €70,000, and over the past month, I've been testing one of their latest wired closed-back models, the Sennheiser HD 620s.

Design and build

The HD 620S come with a 1.8m removable cable. Picture: Noel Campion.

The HD 620s shares much of the same design language as the iconic HD 600 series. Their all-black design and mostly plastic construction don't scream luxury. However, practicality often trumps aesthetics in audio equipment, and the HD 620s are no exception. The ergonomics are where these headphones truly shine. They use a steel plate to close off the back, which Sennheiser says manages internal sound reflections. The plates are angled to encourage the free movement of air, simulating the behaviour of open-back transducers and replicating the triangle image of an excellent loudspeaker system in a well-tuned room.

The HD 620S is relatively easy to drive. Picture: Noel Campion.

The HD 620s have a removable 1.8-meter cable terminated in a 3.5mm jack and a 6.3mm adapter. The included cable will suffice for most users, and the headphones are relatively easy to drive and perform well with various sources.

Comfort and ergonomics

The HD 620S has a good range of adjustability in the headband. Picture: Noel Campion.

The headband padding provides a comfortable fit that avoids the common pitfall of creating pressure points or causing fatigue over long listening sessions. Comfort is crucial for closed-back headphones, particularly for users who plan to edit videos, listen to music for extended periods, or use them on the go.

The ear cups offer a small degree of swivel, which is vital for achieving a perfect seal—a critical factor in getting the best bass response from closed-back headphones. The ear pads are plush and replaceable, a boon for longevity and customisation.

The clamp force is snug but not overly tight, striking a good balance between security and comfort.

Open or closed-back design?

A closed-back design offers several advantages over Bluetooth headphones. Picture: Noel Campion.

I’m a huge fan of open-back headphones because they offer several advantages. The open-back design allows air and sound to pass through the ear cups, resulting in a more natural and expansive soundstage. This design minimises the reflections and reverberations that can colour the sound in closed-back models, leading to clearer, more accurate audio reproduction. However, I can't use my open-back headphones for travel because of sound leakage and the lack of isolation from external noises. Using good ANC Bluetooth headphones is an alternative, but if you prefer sound quality over convenience, the HD 620S is an excellent choice.

Sound quality

When it comes to sound, the Sennheiser HD 620s deliver a balanced and engaging experience.

The bass on the HD 620s is impressive, with excellent presence and extension. It offers a well-rounded low end that complements the overall sound signature without being overpowering. The sub-bass extension is particularly good, adding a satisfying depth to the audio that makes it fun and lively.

The midrange is where the HD 620s truly excel. Instruments and vocals come through with a rich, full-bodied presence that sits perfectly in the mix. The mids are neither too forward nor recessed, striking a sweet spot that offers clarity and detail without sounding harsh or shrill.

The treble is good but not exceptional. It balances between detail and smoothness without veering into sibilance or dullness. While it might not offer the sparkling highs some audiophiles crave, it integrates well with the overall sound signature, providing a pleasant listening experience across various genres.

Closed-back headphones often struggle with creating a natural soundstage, and while the HD 620s don’t rival open-back models, they perform admirably. The soundstage is reasonably wide, and the imaging is precise, making for an immersive listening experience that feels cohesive and well-balanced.

Gaming

The HD 620S are an excellent choice for gamers. Picture: Noel Campion.

I cannot recommend the HD 620S enough for anyone seeking a top-tier closed-back option for gaming. The combination of strong sub-bass, clear midrange, and excellent treble makes it ideal for any gaming scenario. Of course, it doesn’t have a mic, but an external mic is a better solution anyway.

Its precise imaging ensures you can react quickly and accurately to in-game audio cues, giving you a competitive edge. Unlike wireless headphones, there’s no lag, and overall the HD 620s offer an exceptional gaming experience.

Verdict

The Sennheiser HD 620s combine practical design with solid sound performance, making them suitable for a wide range of applications. If you're in the market for a new pair of closed-back headphones, the HD 620s should be on your radar.

Sennheiser HD 620S €350  Sennheiser