Sennheiser HD 6XX Headphones Review

The Sennheiser HD 6XX have a flat sound profile. The frequency response is more aligned with the SoundGuys.com Studio Curve than our own, indicating that they're well-suited to professional audio applications. Their treble range is slightly underemphasized compared to this target, too, which can be crucial in avoiding listening fatigue over long listening sessions.

Note: While the following measurements were taken with our previous testing rig, we've chosen to keep them in this box as they still provide valuable context.

These headphones are a revision of the Sennheiser HD 650 and are often compared in sound to them. However, when we originally tested both headphones, we noticed that they differed in frequency response. After closer examination, we noticed our HD 650 model, which was originally tested in 2020, had lots of wear and tear on the ear cup padding. It can affect their audio delivery as they may not be able to create a good seal or fit. As a result, we purchased a new pair of pads to check for differences between this model and the HD 6XX.

Note that this padding isn't the same as the original padding. It appears that Sennheiser altered their manufacturing in 2021, and there have been reports that the new padding is rounder and a bit stiffer. First, we compared the 6XX's original pass with a new pass using the same pads. It helps us identify if the headphones' padding has worn down enough over time to change their sound. Then we replaced the HD 650's pads and compared them to the HD 6XX, which still have their original pads. After this change, the frequency responses look much more similar. It suggests that wear and tear over time can result in a change in clamping force and, ultimately, frequency response. If you notice that your unit's padding is getting softer or flatter, you can replace it by purchasing a pair directly from the manufacturer.

These headphones have incredible frequency response consistency. If you take the time to secure a good fit, you'll be rewarded with very consistent audio delivery, regardless of your facial features.

They have decent compliance in the bass range with our target. Like many open-back headphones, their low bass is underemphasized, so audio lacks deep thump. However, they can still reproduce punchy kicks and plucky bass guitars accurately.

These headphones have incredible mid-range compliance. The entire range is extremely even, so vocals and lead instruments are clear and present in the mix.

These headphones have outstanding treble-range compliance. While the whole range is very slightly underemphasized compared to our target, the treble response is still very balanced, with few deviations. The slight underemphasis can also be an asset for those who work in sound mixing and engineering, reducing the chance of ear fatigue over long periods of time.

The Sennheiser HD 6XX have a good peaks and dips performance. The frequency response generally follows the flat sound profile in the bass and mid-range, with very few deviations. That said, there's a peak in the low-treble that can help nudge higher-pitched vocals to the front of the mix. Furthermore, the mid-treble is a little uneven, so sibilants like S and T sounds can be alternately dull or piercing.

These headphones have a fantastic stereo mismatch performance. Their L/R drivers are very well-matched in amplitude, frequency and phase, which is indicative of tight tolerances.

The group delay performance is okay. There are two peaks in the group delay that rise above the audibility threshold, in the low-bass and mid-bass respectively. That said, these are frequency bands that the headphones' drivers struggle to reproduce anyway, so the higher group delay doesn't translate to any noticeable looseness in bass notes.

They have a disappointing PRTF performance. While these headphones' open-back design allows them mimic the PRTF response of an angled reference speaker somewhat, they're still not fully able to reproduce the width and immersive quality of such a speaker.

The Sennheiser HD 6XX have an outstanding harmonic distortion performance. There's no audible coloration at both regular and elevated listening levels, meaning you can enjoy clean and pure audio reproduction.

While you should be able to use the Sennheiser HD 6XX with mobile end devices without a dedicated headphone amp, this will depend somewhat on the amplification provided at source. You might find that you prefer how they sound with an amplifier.

These headphones don't have any virtual soundstage features.

These are the settings we used to test these headphones. Our results are only valid when using these settings.

The Sennheiser HD 6XX are open-back headphones with the same design as the Sennheiser HD 650, but with a few minor differences. They're available in a midnight blue color scheme, unlike the gray-and-black Sennheiser HD 650. They have large, oblong ear cups with a metal grille on the outside to help protect the drivers.

These headphones are decently comfortable. They're lightweight, and the ear cups are well-padded, so they feel soft and comfortable against your skin. However, they clamp a bit tighter than the Sennheiser HD 650 and the Drop + Sennheiser HD 8XX, which can feel a bit fatiguing after long listening sessions. It's most likely because these headphones have new pads, though, as the padding can wear down and lower their clamping force over time. You can see the HD 6XX's pad condition here.

These headphones don't have any controls.

These headphones have poor portability. Like most over-ears, they have a big and bulky design, so they may not fit easily into your bag. They also don't fold into a more compact format, and they don't come with a case to protect them when you're on-the-go.

These headphones don't come with a case or pouch.

The Sennheiser HD 6XX have a good build quality. They feel very similar to the Sennheiser HD 650. They're mostly made of plastic, with a metal headband and metal grilles covering the ear cups. However, there isn't a lot of padding on the headband.

They're decently stable. They clamp tight on your head, and they should stay on your ears during casual listening sessions. However, they aren't designed for sports and may fall off your head during more intense physical activity. Also, the wire could potentially snag on something, which could pull the headphones off of your ears.

• Sennheiser HD 6XX headphones
• 1/8" to 1/4" adapter
• Detachable TRS audio cable
• Manuals

The Sennheiser HD 6XX have terrible full range noise isolation due to their open-back design. They don't block out any sounds in the bass and mid-ranges, so you'll be at the mercy of any construction noise that makes its way into your room. While they perform a bit better in the treble range, you may still hear sounds like the hum of nearby A/C units.

These headphones do an awful job of isolating you from the noises you might encounter in common scenarios. If you wear them on an airplane, their open-back design does virtually nothing to block out the sound of rumbling jet engines. They're similarly useless at attenuating the scraping chairs and background conversations of an office, but fare very slightly better with the clamor of a busy street.

Due to their open-back design, they have awful leakage. They leak a lot of sound, and it's audible even in noisier settings like an office. It may be distracting for people around you. Also, the leakage is fuller-sounding compared to that of closed-back headphones and in-ears.

The Sennheiser HD 6XX don't have a microphone.

The Sennheiser HD 6XX don't have a microphone, so the recording quality isn't tested.

The Sennheiser HD 6XX come with a long 1/8" TRS cable, but the cable doesn't have an in-line remote. Latency is almost very for headphones with a wired connection and these cans are no exception.

These wired-only headphones don't support any wireless connectivity.

You can plug in the 1/8" jack of these headphones into your PC's audio out to listen to audio, but the lack of a built-in mic means you won't be able to communicate with online teammates.

You can plug these headphones into your PlayStation controller, but the lack of a microphone means you can only receive audio.

You can plug these headphones into your Xbox controller, but they don't have a microphone, so you'll only receive audio.