A sonic marvel with room for improvement

High-resolution audio on the go isn’t very convenient. It typically involves wired headphones and a DAC (digital-to-analog converter) of some kind, plus your phone or another device to access files or a streaming service. All of this is necessary since Bluetooth compresses an audio signal by design, to allow for low-latency transmission and minimize battery draw. Simply put, wireless headphones haven’t been able to meet the demands of lossless audio, but Sennheiser has come the closest to fulfilling the dream with its HDB 630 ($500).

Thanks to redesigned drivers, a new acoustic platform and a dongle, the company offers up to 24-bit/96kHz audio on the HDB 630 — depending on your configuration. You also get above average active noise cancellation (ANC), a highly customizable EQ, shockingly long battery life and advanced features to fine-tune the headphones to your liking. For some, the best possible sound is still only found on pricey setups and open-back headphones. For everyone else, Sennheiser has provided a taste of the audiophile life in a much more portable package.

Sennheiser/Engadget

Sennheiser moves closer to open-back performance in a set of closed wireless headphones with the HDB 630, but they look more midrange than high-end.

Pros

• Outstanding sound quality
• High-res streaming dongle included
• Lossless audio over USB-C
• Extremely long battery life

Cons

• Expensive
• Basic design with lots of plastic
• Best audio performance requires extra steps

$500 at Sennheiser

Design

Sennheiser says the HDB 630 “inherited” the same chassis from its Momentum 4 headphones. That’s unfortunate because my biggest complaint with that older model’s redesign is how cheap it looked compared to previous entries in the Momentum line. The HDB 630 suffers the same fate, although the splash of silver on the headband and yokes helps things a bit. Simply put, these don’t look like a set of $500 headphones, and since they’re $150 more than their predecessor was at launch, they really should have a more premium appearance.

The outside of the right ear cup is still a touch panel where you can swipe, tap and even pinch to control the HDB 630. I don’t recall another set of headphones with a pinch gesture, and I’m still not convinced it’s warranted. The action is used to enable an Adaptive ANC adjustment that allows you to dial in the amount of noise blocking you need. After the pinch, sliding a single finger forwards and backwards fine tunes the mix of ANC and transparency mode. It’s a nice option to have on the headphones themselves, I just think a triple tap to activate it would be easier to master — and remember.

The only other button on the HDB 630 is for power and Bluetooth pairing. Unless you’re frequently connecting these headphones to a new device, you might not be reaching for this control very often. That’s because the HDB 630 goes into standby mode when you take them off before powering down completely after 15 minutes of inactivity. You can extend that window to 30 or 60 minutes if you prefer. And if the headphones still have battery left, you can return to active mode by simply putting them back on your head.

Sennheiser is betting you’ll use the HDB 630 for long listening sessions, so it outfitted these headphones with soft ear pads and a well-cushioned headband. The clamping force is adequate for a proper ANC seal, but never becomes a burden. And despite being around 20 grams heavier than the Momentum 4, this model still feels balanced and doesn’t weigh you down.

Sound quality

While the overall design may be familiar, the sound platform for the HDB 630 is completely new. 42mm drivers offer what Sennheiser says is “neutral sound with lifelike mids, stunning detail and a wide soundstage.” In order to deliver sound quality that’s as close to open-back headphones as possible, the company overhauled the entire acoustic system, from the drivers to the baffle’s transparent mesh, in the name of balance and clarity. And since audiophile headphones typically require a dedicated external amplifier to achieve their full potential, Sennheiser included a BTD 700 USB-C dongle for high-resolution wireless audio transmission.

When I first put the HDB 630 on, I thought the audio quality was good but not great. Listening over the standard definition SBC codec produced decent results, but it wasn’t anything to write home about. Once I connected to the BTD 700 dongle and unlocked 16-bit/48kHz tunes from Apple Music, though, these headphones really started to impress.

As good as they are, the HDB 630 may not be for everyone. That “neutral” stock tuning places high emphasis on the midrange, so you’ll likely need to make some adjustments to get the bass performance you crave from rock, electronic, hip-hop and other genres driven by low-end tone. While I concede the neutral base is a great starting point, and the HDB 630 does indeed showcase “stunning detail,” I’d argue Sennheiser’s promise of “a wide soundstage” doesn’t always hold true.

These headphones are at their best with more immersive content, like the TRON: Ares soundtrack from Nine Inch Nails. After a slight adjustment, the electronic score had the booming bass it needed, offering driving beats that nearly rattled my brain. All that was layered with rich synths and Trent Reznor’s iconic vocals. The texture and distortion in the instruments came through in greater detail too, something that’s not as apparent on other headphones and earbuds.

Switch over to Thrice’s Horizons/West and the HDB 630 is a different story. Transitioning from synth-heavy electronic music to a genre like rock causes these headphones to lose some of the immersive character they are capable of delivering. You still get absurd clarity and detail, particularly in Teppei Teranishi’s guitar riffs, but the music sounds slightly flatter and a little less energetic. It’s not bad by any means, but some genres won’t envelope you as much as others do.

You can also use the HDB 630 wired over USB-C for lossless-quality audio. Since a number of competitors also do this, I dedicated the bulk of my testing to see if Sennheiser’s wireless dongle is meaningfully different. Of course, I did my due diligence and tested the wired configuration a few times, and it should come as no surprise that the HDB 630 sounds just as good in that setup.

Software, features and accessories

As I mentioned, the HDB 630 comes with Sennheiser’s BTD 700 Bluetooth USB dongle. This enables higher quality streaming than you’ll natively get from most devices. With the BTD 700, you can expect aptX Adaptive and aptX Lossless listening up at rates to 24-bit/96kHz. The dongle also has a 30ms low-latency gaming mode, (supposedly) enhanced call performance and Auracast support for streaming to multiple headphones or speakers. The BTD 700 has a USB-C connector, but it comes with a USB-A adapter if you need it. This typically costs $60 if you buy it on its own, and since you need it to unlock the HDB 630’s full potential, it’s great to see it included in the box.

The HDB 630’s settings and features are accessible in the Sennheiser Smart Control Plus app. And for this model, the company is offering a lot more customization than it does on the Accentum or Momentum headphones. First, the EQ editing options are more robust thanks to a parametric equalizer, which allows you to get a lot more detailed with your custom presets. For example, I was able to add the low-end tone I feel is missing from the stock tuning for those metal, rock and hip-hop tracks I mentioned before. And unlike a lot of headphone apps, adjusting the EQ actually improves the sound instead of just muddying things further.

Another sound-related addition for the HDB 630 is Crossfeed. This allows you to blend the left and right channels so that it seems like you’re listening to speakers instead of headphones. Unfortunately, you only get two options here — Low and High — but the effect certainly enhances the sonic profile of the HDB 630 at both settings.

Despite the BTD 700 dongle’s Mac and Windows compatibility, there’s no desktop version of the Smart Control Plus app. This means you’ll have to change all of your settings with the HDB 630 through your phone before you pair it with both the dongle and your computer. It would be nice if you could make EQ adjustments, create new presets and even change Crossfeed levels without having to reconnect to another device. This also means you can’t be connected to the BTD 700 and both your phone and your computer, since the dongle takes one of the two available multipoint Bluetooth slots.

Active noise cancellation and call quality

When it comes to ANC performance, I’m not entirely sure that the HDB 630 is better than the Momentum 4. But that’s okay. That previous model brought a significant improvement compared to Sennheiser’s older wireless headphones and the ANC is still quite good here. In fact, it was robust enough to block my family’s voices during their calls while I worked from home, and since most headphones struggle with this, that’s no mean feat.

Sennheiser says the BTD 700 dongle will give you improved voice performance over the headphones alone. Specifically, the accessory should provide extended range, clearer voice pickup and, according to the company, “uninterrupted” calls. In my recorded samples, I think the headphones themselves sounded slightly better than when I captured my voice while connected to the BTD 700. However, I noticed a distinct lack of background noise in both clips, which is helpful in busier environments. I’ll also note the overall voice quality isn’t pristine, but it’s clear enough to use for work calls — even if you’re the main presenter.

Battery life

Sennheiser promises that you’ll get up to 60 hours of battery life on a charge with the HDB 630. That’s the same staggering figure the company claims on the Momentum 4. And yes, that’s with ANC enabled, but you’ll only achieve that if you’re listening to standard resolution tunes. Based on my testing with a mix of noise cancellation and transparency mode while I was listening to music and taking work calls, I have no reason to believe the company’s numbers don’t hold true. If you choose to listen entirely via the BTD 700’s higher quality output, you can expect up to 45 hours of use on a charge. That’s still quite a long time considering a lot of the competition runs out at around 30 hours — and that’s without high-res music.

Due to all of the signal processing that helps with the acoustic performance on the HDB 630, they can only be used when they’re turned on. Unlike some wireless models, you can’t use these as wired headphones when the battery is spent. However, if you find yourself with a completely depleted battery, a 10-minute charge will give you up to seven hours of use. The company doesn’t specify streaming resolution for that number, but I assume it’s at standard definition. Still, you’ll get a few hours of higher-res music in that time, which should be enough to get you through a work session, evening commute or that new album you’re dying to play for the first time.

The competition

In the realm of flagship headphones, any company’s top-of-the-line model will set you back $500 these days. I look back fondly on the time when $300-$350 got you the best Sony had to offer. While the HDB 630 is expensive, it’s also in the same ballpark of what you’ll pay for the Bose QuietComfort Ultra Headphones ($450), the Sony WH-1000XM6 ($458 currently) and the AirPods Max ($549). Each of those have their advantages over the rest of the competition, with the 1000XM6 offering the most complete package overall. However, when it comes to pure sound quality, neither of those three are at the top of the heap.

Up until now, that title belonged to the Noble Audio FoKus Apollo. At $650, those headphones are even more expensive than the HDB 630, but their stock tuning will appeal to more listeners and the soundstage is wider and more immersive. There’s also Bowers & Wilkins’ Px7 S3 for a slightly cheaper $479. It delivers the company’s warm, inviting sound and attention to finer details. After spending time with the HDB 630 though, these alternatives are just that — alternatives — as the new Sennheiser headphones are now my pick for best overall sound quality.

Wrap-up

I get it:  in the current financial climate, $500 is a lot to pay for headphones (or anything else, for that matter). You can find a number of perfectly capable sets of ANC headphones for much less given how frequently things go on sale these days. However, what you won’t find is an option that gives you anything close to the performance of audiophile-grade, open-back headphones. That’s really what Sennheiser is doing here, and the HDB 630 slots nicely into the company’s HD 600 series of high-end cans.

As good as the HDB 630 is sound-wise, I can also appreciate that these aren’t the best headphones for everyone. The company’s Momentum 4 is still a very capable set of headphones and it’s now available for about $250. If you crave the best sound quality that still offers the convenience of wireless headphones — and you’re okay with a few extra steps — the HDB 630 is a worthy investment. Just don’t leave home without that dongle.