In this review, I’m looking at a revolutionary new audio product, the HEDDphone D1 open-back over-ear headphones. Many factors make the HEDD D1 an exciting release for HEDD Audio. It marks the company’s first dynamic-driver headphone, departing from their previous exclusive use of revolutionary Air Motion Transformer (AMT) drivers.
This time, HEDD, together with Swedish company Composite Sound) has employed a Thin-Ply Carbon Diaphragm (TPCD), a material prized for its exceptional stiffness-to-density ratio, low mass, and impressive resilience. TPC is no stranger to high-performance engineering either — it’s been used in everything from Formula 1 car chassis to NASA’s Mars helicopter, Ingenuity. The HEDDphone D1 is priced at $799 USD / €699 (incl. VAT) / £599 (incl. VAT).
Disclaimer: This sample was provided by Jackrabbit for an honest review. All observations and opinions here are my own, based on my experience with the product.
HEDDphone D1
Inside the Box
- HEDDphone D1
- Detachable cable
- Velvet cable pouch
- 3.5mm to 6.35mm adapter
Design
Every D1 is made entirely in Berlin, Germany, and it shows. The frame feels solid and purposeful, with just the right amount of flex to inspire confidence without feeling fragile. What’s great is that every part of the headphone is fully serviceable — if something wears out or breaks, you can simply swap in a replacement. It makes you feel the D1 is built to last for years.
There’s generous padding on the underside of the headband, while the perforated velour earpads feel soft and plush. The clamping force is spot on, at least for my head, providing a secure fit without putting too much pressure on the ears, yet never feeling like it might slip off either.
The diaphragm is extremely light, which not only helps the D1 sound fast and articulate but also keeps the design compact and manageable. It’s a genuinely comfortable headphone that you can wear for hours without feeling weighed down or fatigued. At 350g, it’s easy to manage.
The open-back earcups have a smooth, rounded design with metal mesh covers, and the 3.5mm connectors make it simple to swap in third-party cables if desired. Overall, the build quality and comfort are excellent and exactly what I’d expect from a premium headphone.
The included cable has 3.5mm connectors and a 3.5mm termination (unfortunately, there’s no balanced cable or adapter included). It’s not a flashy cable but it is very supple and comfortable to use.
Sound
Sources used for testing include the FiiO QX13, Burson Audio Playmate 3 and iBasso DX260 MK2. At 32 ohms and 100dB sensitivity, it’s not hard to drive. You can plug it straight into a decent portable DAC or desktop setup and get great results, though it clearly scales up when you feed it better amplification.
HEDD describes the HEDDphone D1 as a transducer with the precision of a studio monitor but the intimacy of a high-end headphone — and that actually sums it up pretty well. It feels like they’ve managed to take their studio heritage and shrink it down into something far more personal.
Tonally, the D1 hits the sweet spot between clarity and balance, offering a presentation where nothing feels hyped or exaggerated, just clean and well-controlled. Overall, the D1 brings a studio-grade sense of precision to personal listening without giving up warmth or comfort in the process. In fact, I’d describe the sound as being on the warmer side of neutral, delivering body without introducing artificial colouration.
Bass
The bass response here is genuinely impressive—it’s a real standout feature, actually. It manages to combine that essential depth and authority with seriously excellent control throughout the sub-bass and mid or upper bass. What you get is a low-end that delivers ample weight and satisfying impact without ever getting messy. It’s simply a full, engaging presentation across the board, giving you all the goodness without any downsides. Some might prefer a little more power, though that would compromise its goal of neutrality.
Midrange
The midrange here is a true strong suit, striking a great balance between clarity and warmth. It manages to sound highly resolving and clear yet carries an essential touch of richness—it’s certainly not a cold or analytical presentation. This slight warmth ensures the naturalness of the sound, avoiding the thinness that often plagues highly detailed tunings.
Vocals and instruments come across as highly articulate and textured, featuring a full-bodied presentation that fills the stage nicely. The D1 delivers this level of detail and authority effortlessly without ever tending toward congestion. It’s a versatile and truly engaging sound, offering a rare sense of realism that makes it stand out for complex arrangements and focusing on instrument timbre.
Treble
Moving up to the high frequencies, the D1 maintains that commitment to balance. The treble is neutral and notably smooth in its delivery. You get good extension and a moderate amount of air, ensuring the sound never feels confined or dark, but it certainly isn’t a sparkly or brilliant presentation either.
This tuning pays dividends in texture; high-hats and cymbals sound crisp and realistic—never thin, splashy, or tiring. The overall control is superb, keeping harshness and sibilance well out of the picture. The only minor point is that some of the highest piano notes can sometimes hit with a touch more impact than ideal, but this is a small exception in an otherwise controlled and detailed upper register.
Soundstage & Technicalities
I suspect some readers skipped straight to this section, excited about the staging on an open-back headphone. And while the openness is certainly apparent, it might not be in the way you expect.
I think the true benefit of the open-back design relates more to naturalness and openness, rather than simple stage dimensions. That’s not to say the stage is small—on the contrary, it has good scale and natural boundaries. The real highlight here is the imaging and placement within the perceived space, allowing you to visualise distinct layers in the music, which greatly enhances immersion.
Detail retrieval is, honestly, a touch modest. I was expecting a little more considering the D1’s price point. However, this is likely a result of the neutral tuning, which prioritises listening comfort over micro-detail spotlighting. Overall, its level of resolution remains entirely satisfactory.
Comparisons
Meze Audio 105 AER ($399 USD)
The 105 AER’s bass is more elevated, but both have excellent control and definition in the lows. If anything, the Meze’s mid-bass comes across a bit crisper, a likely effect of its lifted treble response.
The 105 AER has a brighter tonality, which certainly allows crash cymbals to stand out more and provides an edge in perceived clarity. However, this doesn’t directly translate into better resolution, as both headphones perform on a similar level here.
The AER’s sound is designed to be more engaging, whereas the D1 is tuned more for accuracy. Which direction you find more endearing will ultimately depend on whether you’re looking for musicality or honesty.
The treble is softer on the D1, and it does sound legitimately more neutral, whereas the 105 AER’s sound has been sculpted to impress sonically. Overall, these are both great headphones. Arguably, both could be used as studio monitors, but the D1 definitely sounds the more honest representation to my ears.
Sendy Audio Aiva 2
Firstly, Aiva 2’s planar driver is a lot harder to drive and needs more amplification. It has a similar sound signature to the D1, but the Aiva 2’s treble has a bit more energy and air. Similar to the 105 AER, this is an intentional tuning by the Sendy engineers to boost clarity, rather than maintain the most honest timbre like the HEDDphone D1.
The Aiva 2’s mids have a tad more clarity, due to the boosted treble but don’t quite match the HEDDphone D1’s timbral accuracy. Aiva 2 has a slightly wider soundstage and a larger sense of scale and a similar level of detail retrieval.
Physically, the Aiva 2 is significantly heavier, though I find both equally comfortable. Where the Sendy is clearly built to impress visually and audibly, the D1 adopts a more practical and utilitarian design philosophy. One thing is for sure, the Aiva 2’s stunning cable feels a lot more premium than the D1’s plain wire.
Verdict
Well, here we are at the end of what turned into a thoroughly enjoyable review process. Honestly, I didn’t fall in love with the HEDDphone D1 at first listen—let’s just say its style is firmly in the ‘utilitarian’ camp. I’m only human, and sometimes those initial assumptions can cloud your judgment.
But as with all great audio, the magic happens when you stop looking and start listening. The D1 quickly proved its worth by delivering a sound that is simply brilliant in its honesty and control. This headphone isn’t trying to shout about its performance with hyped treble or boosted bass.
Instead, you get a genuine, warmer side of neutral presentation that provides studio-grade precision without ever sounding clinical. The bass reaches deep yet is always disciplined, the mids are full-bodied and articulate, and the treble is smooth and natural. Yes, the detail retrieval is a touch modest for something at its price point, but that’s a trade-off for the fatigue-free listening that highly neutral tuning affords.
Ultimately, the HEDDphone D1 is for the listener who values truth over theatre. If you’re looking for an accurate, controlled, yet genuinely musical headphone that lets the recording speak for itself, this is a top-tier contender. It won me over, and I suspect it will win you over too.
Specifications
Design: Open-back over-ear headphone
Drivers: Dynamic with a Thin-ply Carbon Diaphragm
Frequency Range: 5 Hz – 40 kHz
Maximum SPL: 100dB at 1mW
Impedance: 32 Ω
Pads: Perforated Velour
Cable: Textile-covered premium cable
Inputs: 2 x 3.5mm
Weight: 350g (net)