I use the online alias 16BitAudiophile because I consider myself an ambitious enthusiast who cares as little about voodoo audio as unreasonably priced ultra high-end gear. Give me a good quality CD and I can enjoy it on mid-tier headphones – even over Bluetooth. And the Sennheiser HDB 630 proves it!

Audiophile Headphones Disguised as a Consumer Product

You’d be excused if you mistook the HDB 630 for a premium consumer headphone. It’s dressed with all the expected buzzwords: adaptive active noise cancellation, transparency mode, touch controls, support for the aptX HD Bluetooth codec, a Bluetooth USB-C dongle, an airplane adapter, a fully analog cable, and a travel case. On paper, it looks like the perfect every-day travel companion.

The predominantly plastic build might even suggest that the price is driven by these features. However, when judged purely as a consumer product, the HDB 630 faces some stiff competition.

The Consumer Experience

To be fair, the HDB 630 fulfills its basic tasks, but its value proposition becomes less clear when compared to established leaders. I still have the Apple AirPods Max (which I reviewed five years ago), and they outperform the HDB 630 in key areas like ANC effectiveness, transparency mode naturalness, and seamless Bluetooth connectivity within the Apple ecosystem. They also offer immersive audio with official Dolby Atmos support. And the AirPods Max aren’t even universally considered the best value.

In my testing, the HDB 630’s ANC was inconsistent. In a café, I was amazed at how well it blocked out noise. On the subway, however, the anti-wind feature would activate frequently, reducing ANC effectiveness by 50% or more. After finding the setting to disable anti-wind, I noticed the ANC did a good job with engine noise on a bus, but introduced a faint, high-pitched noise – in this rare case, I preferred to deactivate ANC altogether.

The transparency mode is functional, but doesn’t match the natural, open sound of Apple’s implementation on the AirPods Pro 3 or Max. The touch controls are also present, though I found them less precise for volume adjustments compared to the tactile crown on the AirPods Max.

On my iPhone, the HDB 630 would briefly cut out sound after a few seconds – likely as it adjusted the codec or bitrate – and also when switching between ANC and transparency. Using the included BTD 700 dongle introduced noticeable latency, putting videos out of sync unless switched to its game mode. While the dongle advertises lossless transmission, the headphones themselves have their own limitations. A minor, but consistent, quirk is that the HDB 630 never automatically reconnects to my iPhone; I have to manually select it from the Bluetooth menu.

When stacked against the user experience of the AirPods Max or AirPods Pro 2, the HDB 630’s convenience features feel a step behind. For a user prioritizing seamless integration and top-tier ANC, the value is a harder sell.

But There’s More: The Audiophile’s Playground

None of the above are deal-breakers. However, the HDB 630 has a suite of features that the average user might overlook, but that speak directly to an enthusiast’s heart.

It allows the use of a 5-band parametric equalizer. If you read my RME ADI-2 Pro review on Headfonics (oh my, that was already 9 years ago!), you know this is a feature I hold in high regard. The Smart Control+ app isn’t as intuitive as the RME’s interface, but the results are similarly powerful. I don’t expect an inexperienced user to achieve good results with the PEQ, but fortunately, none of my readers are ;). (And before we get to sound, the HDB 630 is one of the few headphones that may not even need EQ, but having the option is still awesome.)

To top it off, Sennheiser implemented crossfeed. As an avid jazz listener, I love crossfeed. I can’t stand trumpets coming from one side only, and even the low setting does a great job of creating a more cohesive, three-dimensional image with only a tiny bit of smear.

One feature that is missing is equal-loudness correction. As we’ll see, the stock tuning is excellent and fairly neutral. However, at low volumes, the bass drops out a bit, and the sound can become rather dry. An equal-loudness contour could mitigate this by adjusting the frequency balance at lower volumes.

What Really Matters

Now, let’s get to the heart of what makes the HDB 630 stand out: its sound quality.

Tonality

Sennheiser has had its hits and misses with tonality, but the excellent midrange of the 6-series line-up is legendary. The HD 650, the even more neutral HD 600, and the more affordable HD 6xx are all among the best in their categories – and have been for over 20 years! However, there have been some missteps in the line, like the closed-back HD 630 VB. So, approaching this new HDB 630 with caution made a lot of sense.

Fortunately, the use of DSP has helped Sennheiser bring the new 630 on track. By default, its frequency response resembles a sloped Diffuse Field target with a boosted bass. This is widely appreciated in the audiophile community, and we have to commend Sennheiser for being one of the first to release a product that aligns so closely with this optimal tonality.

In practice, this means the HDB 630 sounds fairly neutral in its stock settings. There’s no way to bypass the pre-configured DSP, as even the included analog cable connects to an internal ADC. So, you can rest assured the HDB 630 will generally sound great, no matter how you connect it.

Bass

By default, the HDB 630 has a “new meta” shelved bass curve. The sub-bass is boosted considerably, while the upper and mid-bass are kept lean and neutral. This is exactly what many in the community want. Personally, I find this tuning can sometimes lack fullness and body. Some songs sound thin, while others can feel overpowering in bass presence.

I have two PEQ suggestions for a more homogenous and natural bass tuning:

  • Low Shelf at 70Hz of -3dB with 0.7Q
  • Peak Band at 170Hz of +1.7dB with 2Q

With both corrections applied, the bass curve flattens nicely for a more consistent presence while maintaining a steady elevation towards the very low end.

With or without my EQ, the bass is well-controlled, tight, and has authority when demanded. You won’t get basshead levels of headroom, nor unheard-of textural detail. Its character strikes a balance of wetness and tactility, serving as a great all-rounder. That description might sound middling, but for a closed-back headphone, this is actually very commendable.

Mids

If you’ve read this far, you’re likely interested in the HDB 630 because you enjoy the legendary Sennheiser midrange. And to keep it short: yes – even if accomplished through DSP – the HDB 630 has that sweet and easy natural timbre that made Sennheiser famous. (BTW, here is my recent take on the HD 650.)

If you want to be nitpicky, this headphone can have a rare tendency to sound slightly honky and thin. I have two different PEQ suggestions to even this out:

  • Peak Band at 980Hz of -1.5dB with 5Q
  • Peak Band at 3.1kHz of -2dB with 4Q

The tuning is great either way, and the 630 is nearly transparent in the mids. Especially for a closed headphone, the mids sound airy with excellent imaging. Personally, I use crossfeed most of the time, which improves the soundstage to a great size for this category.

Treble

As measurements and other reviews point out, the treble experience is dependent on positioning and individual HRTF. I can only speak for myself. I experience the high frequencies as somewhat gritty, with overpronounced harmonics, especially from 11 kHz and above. This area can accentuate noise in a recording and small details like vinyl scratches. While this can seem hot, it’s preceded by a cut in the treble around 8 kHz that balances the overall quantity. In effect, some cymbals can lack fundamentals and overcompensate with harmonics, making them appear brighter than expected.

I’m hesitant to recommend my specific PEQ settings here, as the treble seems very fit-dependent. Other reviewers I trust have reduced 10kHz, which, for me, is exactly where it should be. I don’t think this variance is specific to the HDB 630, but equipping users with a PEQ practically invites audiophiles to find their perfect setting.

I don’t think the treble is the main quality HDB 630 users will seek. If it is, they might be disappointed. This is a closed-back headphone, after all. It’s physically challenging to create a natural, airy, and expansive treble in such a confined space. So, in the end, the highs are good enough for me. They are actually damn good with EQ, but I’m not sure if a violin purist would be entirely convinced.

Sound Verdict

The Sennheiser HDB 630 is an impressive statement! The stock tuning is uncompromised, hardcore audiophile territory. A typical consumer headphone would likely have warmer, richer mids and softer treble. As you can see from my settings, even I dial the “neutrality” down a notch. But even then, I could get very used to it and enjoy it for most of my music. The resolution is fantastic for a wireless headphone. I genuinely don’t wish the HDB 630 had a passive mode – and that, in itself, is incredible!

Final Thoughts

By default, the Sennheiser HDB 630 can sound forward and intimate, with depth mostly coming from the sub-bass. Tracks without much low-end information will feel very close to the listener. But overall, the tuning is very close to the experience of the HD 600 or 650. It needs only a few adjustments to create a truly excellent, customized sound, and that capability allows the HDB 630 to outperform every wireless headphone I know, and even most closed-backs as an all-rounder.

The audiophile-grade tuning comes with the convenience of great compatibility – wired with a 3.5mm cable, via USB-C, or through improved Bluetooth with the included BTD 700 dongle. None of this is “ultra-high-end,” but this setup will get you into audiophile territory quickly, with bonus features like ANC included.

The Sennheiser HDB 630 is not a headphone I would recommend blindly. There’s a large user base that may not appreciate the stock tuning – which could come off as aggressive and shouty – nor know how to use an EQ. But for those who do, the HDB 630 becomes a deeply personal product – and probably the best-tuned headphones yet.