HEDD Audio HEDDphone D1 Review: The Disruptor

I think most in our sphere would agree that HEDD Audio has fit squarely into the mold of a professionally-targeted speaker brand still working to find their footing in the audiophile headphone sphere… but I think that’s about to change. With their newest HEDDphone D1—an $800 USD open-back dynamic driver headphone—HEDD is making one thing eminently clear: they’re ready to be a serious competitor in the audiophile headphone space.

HEDDphone D1 represents a series of firsts for HEDD: It’s their first dynamic driver headphone, and the first audiophile headphone to use a “Thin-Ply Carbon Diaphragm”. It’s the first “HEDDphone” priced under $1000 USD, and most interestingly, it’s the closest HEDD has come to making a truly well-rounded headphone, paying equal attention to industrial design, comfort, serviceability, tonal neutrality, and of course, subjective performance.

With HEDDphone D1, HEDD seems intent on filling the “Sennheiser HD 600 Upgrade”-shaped hole in the market. It makes sense, because everyone wants that, but achieving that goal in earnest is not an easy task.

Many brands’ prior attempts end up sacrificing tonal balance in pursuit of excitement, and often don’t take things like the HD 600’s excellent build quality, serviceability, or its eminently reasonable comfort & design profile into account. This leads to most supposed “HD 600 upgrades” being more compromised overall than the headphone they’re supposed to be an upgrade from.

Which raises the question: Is HEDDphone D1 just another “HD 600 Upgrade” that sacrifices well-roundedness in favor of X-factor, or did HEDD finally make the HD 600 upgrade that everyone has been asking for? Let’s find out.

Before we get into the review proper, I want to remind people that we also have a video review from Resolve for those who prefer video content, and you can watch that on our YouTube Channel The Headphone Show below: Watch the video

Build, Design, Comfort, and Accessories

Starting with the accessories, it’s a pretty simple package. Buyers receive a hardshell zip case, a 6ft dual-3.5mm TS to TRS stereo cable, a 6.3mm TRS adapter, and a little baggie for holding the cable.

NOTE: This is a pre-production unit that is missing one accessory that will come in the production packaging—a “dust removal sticker” pack, to help clean the earpads which can attract dust.

The cable itself is quite compliant and soft, wrapped in a fabric material not unsimilar to what comes with the HEDDphone TWO GT, though in this case the cable isn’t braided. While I enjoy the lack of shape memory this cable has, I did notice it was a little more prone to tangling than other cables I have on hand. It’s also very slightly microphonic above the Y-split, and while this isn’t a huge issue to me, it may bother some people who move around a lot when wearing headphones. That said, the cable strikes a nice balance of softness and length and has been pretty painless to use.

The hardshell case is fairly uneventful, having only enough room for the headphone and the cable. Similar to other audiophile dynamic driver headphones like those from Sennheiser or Focal, the HEDDphone D1 doesn’t fold down for storage. For that reason, it’s maybe a slightly less portable headphone, but it’s open back, so you’re not gonna be using these in shared spaces anyway. Overall, the accessories package here is fine and I don’t really have any complaints, but I would’ve liked if the cable was a bit more similar to the braided one that came with HEDDphone TWO GT. Let’s move onto the build and design.

In the hand, HEDDphone D1 feels like a well-considered balance between solid and lightweight. At 350g, it’s not the lightest headphone in the world, but it’s far from the heaviest, especially when compared to other audiophile dynamic driver headphones like the Focal Elex which is 100g heavier. The cups have plenty of swivel, while stopping short of rotating a full 90 degrees. There’s no suspension strap, and the overall design feels reasonably evenly-weighted between cups and headband, and all of these factors lead to HEDDphone D1 feeling very stable and “not floppy” in the hand & on the head.

An important note when it comes to HEDDphone D1’s build is that every single part here is intended to be replaceable. The headpad and earpads are affixed with clips, and the baffle, chassis, and headband are all removable/replaceable. All too often headphone companies don’t consider making products that are built to last and be serviced, and HEDD taking care to make sure their most affordable headphone is also serviceable is something that deserves a very positive callout. This is a big thing for a headphone that costs $800, and HEDD is one of the few brands I’ve encountered in this price range doing this right. Big, big points here.

There’s a certain German austerity to the visual design here, but in my opinion HEDDphone D1 looks absolutely awesome. The monochrome black colorway with slightly oval-shaped cups and the low-profile, industrially-tinged features makes for a headphone that looks great on a stand and doesn’t distract or look strange when worn. Considering most audiophile headphones look outright weird on the head, I love that HEDDphone D1 goes for something more subtle, versatile, and… honestly just good looking.

The functional aspects of the design very clearly take cues from the Focal headphones as well as the Sennheiser 6 series headphones. It uses a similar type of earpad to the Focal Elex (perforated velour on memory foam, pads are removable via clip system), but with a slightly taller/deeper pad opening. It also uses a similar headband & arm system to the Sennheiser HD 6 series, but with a thicker, wider velour-wrapped headpad and a much, much more satisfyingly “clicky” arm-length adjustment. I love clicky headband adjustment systems, so this makes me happy any time I put the headphone on my head; underrated touch here.

Which brings us to the comfort, where I think the HEDDphone D1 has a chance to be really excellent for some people, even if it’s not 100% perfect for me. The earpads being ear-shaped and neither small nor large means I think they’ll be sufficient to fit around most people’s ears while having minimal potential for gaps under the ear where the jaw begins. While I personally wouldn’t say no to a larger or deeper earpad—more room is typically always better—I think they struck a nice balance here.

That said, the headband being similar to the Sennheiser HD 6 series means it has a few things I like about it, and a few things I don’t. The main thing I don’t like is the lack of suspension strap, especially because the headpad is quite stiff and doesn’t really fit my head’s natural angles super well. In the beginning of my testing, the bulk of the weight sat on the inner corners of the headpad indentation and I got hotspots somewhat quickly.

However, because this is similar to the HD 6 series headband, it has the same metal extension arms that can be bent (with care) to either increase or reduce the clamp. I opted to increase the clamp by bending the arms inward, as well as sizing down the headband by one click vs. where I started. Both changes displaced some downward force off the top of the headphone with inward force, improving comfort significantly.

Additionally, the HEDDphone D1 is a fairly clamp-sensitive design when it comes to the sound over 3 kHz: more clamp force results in less treble around 6 and 11 kHz, and vice versa. So if you have a larger head, you may find HEDDphone D1 a bit darker than some measurements/impressions suggest, while smaller heads may hear it to be a bit brighter. I personally found it a bit brighter before increasing the clamp, and it’s a happy coincidence that the change I made for comfort also ended up making the headphone sound better for me. Makes me curious what kind of effect a Capra Strap, which usually increases clamp, may have.

Overall, HEDDphone D1 strikes a solid balance of function, form, visual appeal, stability, and serviceability. In fact, HEDD may be the first company I’ve seen offer an industrial design worth comparing favorably to the Sennheiser HD 6 series. While I think the cable could’ve been more premium, every other non-sound factor in the package here is about as well-executed as I’ve seen, and some of the more unique aspects like serviceability (especially with HEDD’s 5-year warranty) represent a big win for consumers.

Let’s move onto the sound.

Sound

Starting down low, the bass is very well-extended for an open dynamic-driver headphone, roughly on par with the well-extended Focal headphones like the Elex and Clear. In fact, I’d say there’s some level of shared DNA between the bass of HEDDphone D1 and something like the Elex. There’s a similar chestiness to kick drums and a fullness of character to bass instruments and low-pitched male vocals.

While the bass is well extended, it’s definitely not elevated, so there’s no extra distinction or emphasis of bass separate from what’s in the track. I’m personally partial to this kind of presentation myself, as I find it conveys bass instrument timbre best while not drowning midrange instruments in bass fundamentals or decay.

In the upper bass and lower midrange we get a very slight push to warmth, which helps vocal and snare drum fundamentals elevate just enough that nothing sounds lean or lacking in density. But again it’s very slight. I would have no issues with a bit more warmth here, but I actually think less warmth may have been a bit of an issue.

As an open dynamic driver headphone, HEDDphone D1’s bass is definitely the least prominent contributor compared to its midrange or treble. So while there’s great bass extension and a slight warmth and fullness, the bass is not the star of the show. This does mean HEDDphone D1 never sounds decisively “thick,” even if it has thumpiness down low when called for. However, because it isn’t super warm or bassy, it portrays quicker passages with an agility that a bassier or warmer headphone—like an Edition XV or an HD 650—would probably have a hard time keeping up with.

Moving to the midrange, this is where it becomes obvious that the HEDDphone D1 is not just another expensive headphone that bets the farm on exciting colorations: HEDDphone D1’s midrange is among the most linear midrange tunings you can find in over-ear headphones, regardless of price.

What this means is that basically all real instruments—pianos, bowed and plucked strings, guitars, horns, woodwinds, and voices—sound about as correct as I’ve ever heard, and on some recordings, the best I’ve heard. HEDDphone D1’s midrange is actually the closest I’ve found to my “ideal” EQ profile with my HD 800. People who are sticklers for midrange neutrality shouldn’t have any concerns when it comes to HEDDphone D1, except for maybe one thing.

HEDDphone D1 is similar to HD 600 in that it slightly overshoots the 3 kHz area and relies on balance from a bit of 100-200 Hz bloom to level out this forwardness. So people that find HD 600 shouty may also find HEDDphone D1 shouty. But of course, this means the myriad people who like HD 600 and HD 650’s mids will almost certainly also like HEDDphone D1’s mids.

Okay so the bass is good, the mids are great… What about the treble?

Well, this is unfortunately where this headphone falls a bit short for me. Now I only say “a bit,” and I mean it, because there are things I like about the treble here. Specifically, I detect a bit less of a recession in the 5-8 kHz range vs. what I typically get with other headphones. This results in the HEDDphone D1 sounding a bit less disjointed and “dark-bright” (dark in some spots, bright in others) than other headphones like the HD 600.

The tippy top of electric guitars resides around 5-8 kHz, and I find HEDDphone D1’s treble commits an appealing “wireyness” that makes them sound really lively and expressive. I like that HEDDphone D1 does this while the overall treble profile doesn’t go quite far enough to make it an outright bright headphone.

That said, to my ear there’s a big spike right at my pain point around 10-11 kHz which is a big enough issue for me to notice consistently across genres. It seems to affect cymbals and female voices in particular more than male voices, strings, drums, or acoustic guitars, and causes them to be a bit too “tizzy,” almost like they’ve been artificially sharpened or excited.

I mentioned earlier that the treble changes quite a bit with clamp, but it’s also quite variant based on positioning, possibly due to the angling of the drivers. This matters because I usually wear headphones situated as far forward on my head as possible, with my ear close to the back of the earpad, but this position sounded pretty rough with HEDDphone D1.

The best spot for me, where the ~11 kHz elevation was most relaxed, was actually with my ear placed squarely in the center of the earpad. So for those who hear HEDDphone D1 and find this area to be an issue, try playing around with positioning.

Even with the treble not being perfect for me, it’s really hard to be mad at the tuning here. As said, bass is good, midrange is great, and even if the treble’s not perfect, I think most audiophiles are going to find it pretty livable, because it’s still more well-controlled than most other headphones in this price range.

Potentially the most compelling aspect of HEDDphone D1 for audiophiles is that it may deliver what people have wanted for more than two decades: the HD 600 with bass extension and better “technicalities”. For me, the latter unfortunately comes at the direct cost of the treble not being as smooth as I’d like, but I think most audiophiles who buy an $800 headphone are expecting something that sounds more expensive, and in this case I’d wager it’s likely that HEDDphone D1’s treble results in these expectations being met more often than not.

While yes, HEDD absolutely could’ve chosen a more “exciting” tuning to maximize performance in dynamics or detail or spaciousness, as it stands HEDDphone D1’s tuning is its biggest strength, and I think diluting it would be a mistake.

And yes, while they could’ve tuned it for a bit more smoothness in the treble, it’s likely that audiophiles in their infinite thickness would decry this smoothness as a “lack of detail” or some other sort of intangible lack for the price.

HEDDphone D1 is neither a space-focused headphone like the HIFIMAN stuff, nor a relentlessly slammy headphone like the Focal stuff… but it does those things meaningfully better than the HD 6 series while not compromising much at all when it comes to tuning. This is no small feat.

If headphone tuning is always a compromise—and don’t get it twisted, it absolutely is—then the compromise HEDD opted for here with HEDDphone D1 is among the best balances I’ve ever encountered. So now let’s talk about how it compares to a few of my other favorite headphones.

Comparisons

Vs. Hifiman Edition XV

Edition XV is my newest infatuation. After my review, it quickly became my daily driver because the treble response is as close to perfect (for me) as I’ve heard in an over-ear headphone. That, combined with its cozy midrange & full bass extension, makes for a very chill, easy to vibe with headphone listening experience that doesn’t have any deal-breaking flaws.

While I think I’d reach for Edition XV over the HEDDphone D1 most times, it’s basically only because of the treble. In every other aspect—build, comfort, looks, serviceability, and every aspect of sound quality outside of treble—HEDDphone D1 is simply a better, more complete headphone.

Now of course, it’s more expensive and is going for something completely different, but I cannot stress enough how clean of a sweep it would be for HEDDphone D1 if the treble was just a little bit smoother. D1 has a meaningfully more tactile, textured, dynamic presentation, a way better midrange presentation, and a comfort/build profile that screams quality while not looking ostentatious or feeling like it opts for form over function.

I love the Edition XV’s treble, but I can’t say I would recommend the Edition XV over the HEDDphone D1 considering how solid of an all-rounder the latter is. Even if Edition XV is a very “me” headphone, the appeal of HEDDphone D1 seems like it has potential to be much more universal.

Vs. Focal Elex

Certainly an interesting comparison, not least because Focal are basically the only other people making dynamic driver headphones in this price range that have any claim to neutrality. Before I received HEDDphone D1, I figured Elex—my favorite of the Focals—would be the most natural comparison given the pricing and tuning… but after listening for a while, I don’t really think their presentations have much in common outside of the bass.

Elex (and Clear) were the first dynamic driver headphones of the modern era to be heralded as the “HD 600 upgrade”. And while yes their broad-strokes sound signature is very reasonable, the Focal open backs absolutely have colorations that, for me, mean they’re going for something quite different than HD 600.

I think the biggest surprise is how much darker the Elex is than the HEDDphone D1 (and most of the other headphones I have around). Perhaps it’s due to pad wear—this unit is a demo unit we’ve had at CanJams prior—but the 4 kHz dip the Elex has is particularly noticeable when compared directly to HEDDphone D1, even though the latter doesn’t really sound particularly forward in this region to me.

To my ear, with this unit at least, Elex is a bit smoother of a listen than HEDDphone D1, as well as a more noticeably bassy headphone; I assume the relaxed treble is tilting the response more towards bass. Kick drums or aggressive swings in overall mix volume really come alive on Elex with an intensity HEDDphone D1 doesn’t quite match.

However, HEDDphone D1’s midrange is much better, avoiding the awkward spotlighting effect Elex gives to horns and hard-struck pianos, or the nasality imparted to certain vocal recordings. HEDDphone D1 also has a more complete, “detailed” sounding treble response; while I think for my taste the Elex performs better above 10 kHz, I actually prefer how the HEDDphone D1 handles the treble under 10 kHz. Again, it sounds more complete and visceral, even if the trade-off is seemingly less thumpiness in the bass.

When it comes to comfort, I prefer the HEDDphone D1’s weight, earpads, and overall industrial design, but I find Elex’s headband a bit more comfortable on my head, likely just because its angling fits my own head a bit better. That said, neither has exceptional headband comfort for me, and I would almost certainly end up getting a Capra Strap for either of them anyway.

Elex has basically been the default answer for “HD 600 upgrade” since its release, but HEDDphone D1 strikes me as a potentially better answer, if only because HEDDphone D1 actually shares a lot more in common with the HD 600 than the Elex does. It still improves on the things the Elex improved on compared to HD 600, but I find HEDDphone D1 has significantly better overall timbre—which is a shortcoming of Elex’s—while also being a better platform for weight and longevity/serviceability.

Vs. Sennheiser HD 600

So now we come to the important question: how does HEDDphone D1 stack up to the HD 600?

Surprisingly well, actually. In fact, in a back to back comparison, I can’t help but feel like HEDDphone D1 has a controversial future ahead of it… because I think a lot of people are going to find HEDDphone D1 to be outright better.

What the HD 600 does well is its value and its “directness” of presentation. For under $500, you get a very well-built, well-tuned, “resolving” pair of headphones that really lets you peer into the music and pick it apart. But its main downsides are some incompleteness in bass and treble, the lack of spaciousness for some listeners, and the comfort still potentially having some weaknesses.

HEDDphone D1 is much better at handling low bass notes in electronic or hip-hop music, but it’s also more filled-out in the mid-treble on my head and, surprisingly, less bright than the HD 600 (and HD 650) above 11 kHz. The upper treble has always been a big issue with the 6 series headphones for me, so it’s nice to see the HEDDphone D1 be a bit more polite up there. Even if it means the euphonic “chirp” of the 6 series treble is absent on HEDDphone D1, I think it ends up a bit more versatile for it.

HEDDphone D1 may not be the punchiest or the most spacious headphone, but it improves meaningfully on HD 600’s performance in these aspects. It has a more precise “thwack” on snare drums, better articulation on things like plucked strings, and keeps up better overall with any fast-paced changes. It does this, while also having a more panoramic soundscape compared to the HD 600’s “3-blob” presentation.

The midrange is also so goddamn close that it’s hard to say I have a discrete preference between the two. There are recordings where voices sounded noticeably better on HEDDphone D1 than HD 600 or 650, and vice versa. What’s so impressive to me is that HEDDphone D1 meaningfully upgrades the totality of the “subjective” package here, while not totally abandoning the excellent timbre or direct, focused presentation that makes the HD 600 and 650 so addictive.

Adding all of this to the fact that HEDDphone D1’s comfort is clearly better for me due to thicker ear and headpads, this means HEDDphone D1 collects a clear win in comfort, bass, treble, subjective aspects, while being tied for midrange with basically the best midrange available in headphones.

Now, all of this would be a bit less confidence-inspiring if the HEDDphone D1 didn’t bother to match Sennheiser’s excellence in build and serviceability, but it seems like HEDD has gone through the effort to make sure that’s taken care of too.

Which means I can only come away with one conclusion here: the HEDDphone D1 is the closest I’ve encountered to an all-around HD 600 upgrade in the modern era of audiophile headphones. I obviously prefer a good few headphones to the HD 600 (like the Elex and Edition XV), but HEDDphone D1 is the first I’ve encountered that I think even die-hard HD 600 fans may prefer to the legendary neutral reference, because it delivers essentially the same performance in the areas that HD 600 gets right, while improving almost everything else.

Conclusion

Reviewers and consumers have been asking for the “HD 600 with bass extension and more ‘detail’ and ‘soundstage’” for longer than I’ve even been in the headphone hobby. The idea that we finally received something that delivers on more of those promises than anything prior is… frankly a bit hard to believe.

I’m aware this review is very positive. I’m not only aware, but actively a bit self-conscious about it. I would obviously prefer to avoid being overly congratulatory to a headphone that doesn’t deserve it, but HEDDphone D1 is undeniably solid in a way I’ve basically never encountered in this product space.

Readers may notice I didn’t compare HEDDphone D1 to many other headphones that are the same price or more expensive, and that’s because those headphones—in my opinion—simply do not compete with HEDDphone D1 (or the headphones I compared it to) when it comes to blending sound quality, build quality, and comfort.

Most headphones are so compromised from top-to-bottom that it’s typically quite easy to find myriad flaws and write a whole review detailing all of them. This is not the case with HEDDphone D1. It’s eminently clear that HEDD took as many steps as possible to ensure this was not only a good headphone, but a great one, and it also happens to be their least expensive offering to date.

HEDDphone D1 is a landmark release in a year seemingly filled with landmark releases (seriously what the hell is going on this year), which is why I’m happy to give it my full seal of approval, and my enthusiastic recommendation not only for audiophiles, but for HEDD’s original audience in the pro-audio market too.