The Grell Audio OAE2 and the HEDD HEDDphone D1 are two similarly priced, dynamic driver studio-grade open-back headphones.
The D1 launched in late 2025, the OAE2 in the spring of 2026. At launch, the D1 was priced at $799 / €699 / £599, the OAE2 slightly more affordable at $599 / €499 / £499.
The HEDDphone D1 uses a 50 mm driver with a thin-ply carbon diaphragm (TPCD) and a traditional driver placement. The Grell OAE2 uses a 40 mm driver with a bio-cellulose diaphragm and a very untraditional driver placement: the OAE2 features extremely angled drivers that are positioned entirely in front of your ear, in an effort to simulate a near-field speaker experience.
My full HEDDphone D1 review is here: HEDDphone D1 Review,
My Grell OAE2 review can be found here: OAE2
HEDDphone D1 SPECIFICATIONS
- Type: Open back full size
- Driver size: 50 mm
- Driver type: Dynamic TPCD
- Impedance: 32 Ohms
- Sensitivity: 100 dB
- Cable: 2 m detachable
- Cable headphone connectors: dual 3.5 mm
- Cable termination: 3.5 mm jack with screw-on adapter
- Pads: detachable ring with “lip-and-groove mounting”
- Fully modular and serviceable
- 5 years warranty
- Carry case included
- Weight: 356 g (measured)
HEDD Audio: Headphones D1
GRELL OAE2 SPECIFICATIONS
- Type: open-back full size
- Heavily angled drivers, positioned in the front of the cup
- Driver: 40 mm dynamic
- Diaphragm: bio-cellulose
- Impedance: 38 Ohms
- Sensitivity: 100 dB
- Frequency Response: 12 Hz – 34 kHz
- THD: 0.05% (1 kHz, 100 dB)
- Pads: Velour
- Cable: 2 x 1.8 m single-sided, material: silver plated OFC.
- Cable connector 2.5 mm 4-pole on headphones
- Cable termination: 4.4 mm balanced jack or 3.5 mm with 6.35 mm adapter
- Transport case included
- Fully modular and serviceable
- Weight: 378 g
Grell Audio: Products
BUILD AND DESIGN
Both headphones are built with studio use in mind and are fully modular and user-serviceable, which vastly reduces the cost of repair. Both feature a padded headband with no headband strap. The D1 offers more and softer headband padding than the OAE2.
Both headphones have good swivel action, but only the OAE2 can be laid flat for storage, though I find this of limited practical value. Both come with travel cases.
Both headphones come with detachable cables, but of different types.
The D1 uses a dual-entry 3.5 mm cable that connects to both cups. This is a standard connection method these days, making it very easy to find third-party cables in different lengths, qualities, and terminations.
The OAE2 cable connects on one side only (user-selectable) via a 2.5 mm 4-pole TRS jack. This makes third-party cables harder to find, especially given the small sleeve/hole the 2.5 mm jack must fit into.
Both headphones come with detachable pads. The D1 uses a connection ring that can host all typical standard lip-and-groove type pads. The OAE2, on the other hand, uses a very proprietary connection mechanism due to the angled driver and limited space. It is very difficult to use third-party pads on the OAE2, as it would require an adapter that is not (yet) available.
I find both headphones comfortable enough in use, though I prefer the D1 in this regard, thanks to its softer pads and better weight distribution from the headband.
LISTENING COMPARISONS
Associated equipment:
- Amplifier: Topping A90
- DAC: RME ADI-2 DAC FS
Eye of the Day by Marta del Grandi
The D1 is very nicely balanced with beautiful vocals: warm, smooth, and detailed. The OAE2 is also good but noticeably drier and crisper, but also sounding more articulate and a bit tighter.
How Deep by John Scofield
The OAE2 sounds very spacious with excellent imaging and image depth, and is very well balanced. The D1 is somewhat warmer and smoother, but at the cost of some articulation and instrument separation.
Yours by Bill Laurence
The D1 is very well balanced with great instrument separation. The bass is clean with nice warmth but not overpowering.
The OAE2 is actually very similar, though a bit tighter where the D1 is a tad smoother. The imaging and instrument separation are a tad better on the OAE2, and the sound is positioned a bit more in front of you.
Train to Tokyo by Vega Trails
The D1 sounds very spacious with excellent imaging and a strong sense of three-dimensionality, especially depth. It is also very well balanced, with all frequencies coming across coherently.
However, while the D1 is excellent, directly compared to the OAE2 the OAE2 edges ahead in terms of imaging, but has a slightly drier tonality where the D1 is slightly warmer and smoother.
Re-Melt by Tord Gustavsen Trio
The OAE2 is very snappy and slightly crisp, with well-articulated detail, superb imaging, and excellent tonal balance. The D1 is not quite as strong in terms of instrument separation and imaging, but its tonal balance is similarly good, and there is a slightly warmer and smoother delivery that is very appealing.
Outlaws by Bill Frisell
The D1 is well balanced, spacious, and detailed. The OAE2 does however have significantly more space between instruments, with a better sense of imaging and depth. It is again a bit crisper and drier in its timbre, but that makes detail feel more articulate and stands out more.
The Hidden Camera by Photek
The OAE2 is extremely dynamic and snappy, with really impressive bass that goes deep and has lots of texture. With the D1, the bass is less prominent, things are a bit smoother, and articulation is not as strong.
Sujet Tabou by Renaudin and Olivier Cahours. (Douö)
The D1 sounds excellent with this very dynamic and explosive acoustic duo of percussion and classical guitar. The OAE2 is similar, even a bit tighter and with slightly better imaging, but again with a drier character.
Like Suicide by Soundgarden
This track sounds excellent with the OAE2, where the excellent instrument separation, tonal balance, detail, and great dynamics really make it shine. The D1 is close but sounds slightly less articulate – things blend more together – making the OAE2 my preferred option here.
Vicarious by Tool
The D1 sounds very good, with great tonal balance, a strong sense of neutrality, and a touch of warmth. The OAE2 is quite different here: more distant, “harder” sounding, and too dry for my taste.
Summer 3 Vivaldi Recomposed by Max Richter
The OAE2 delivers sharply cut strings and a large soundstage. The D1 is smoother and a bit fuller, making for a more pleasant listen.
Young Vivaldi by Modo Antiquo
The D1 offers excellent string timbre, detailed and smooth with enough bite and attack without sounding hard. The OAE2 is thinner and sharper but with better instrument separation.
Spontaneous Compositorius by Thomas Agergard
The OAE2 delivers a smooth yet textured saxophone, the bright percussion is a tad sharp but clean, and bass that is tight yet still rich enough.
The D1 has a warmer saxophone, a slightly smoother presentation of the bright percussion, and bass that is a tad less tight but still detailed.
WRAPPING IT UP
Sound Signature
The OAE2 and D1 have quite similar sound signatures, both neutral but with well-present bass. The D1 is a bit smoother and warmer, while the OAE2 is a bit sharper and drier.
Treble
Both have quite neutral and clean treble, with the OAE2 being a bit sharper and crisper and the D1 slightly smoother.
Midrange
Both deliver a very present and detailed midrange, with the D1 sounding a bit smoother and the OAE2 a tad crisper and drier.
Bass
In terms of bass quantity they are pretty similar, and in terms of quality they are quite close, though I think the OAE2 mostly has a bit better control and sounds a tad tighter.
Soundstage and Imaging
Both have good soundstage size and imaging capabilities, more than adequate. However, in direct comparison the OAE2 consistently offers better instrument separation, a blacker background, and generally better imaging, with especially a better sense of depth.
In other words, the D1 is a headphone with solid imaging, while the OAE2 takes you into an experience slightly more resembling near-field monitors (to a degree).
Detail, Dynamics, and Timbre
In terms of raw detail retrieval I think they are on the same level, though they deliver detail in different ways. The D1 is smoother and more subtle, while the OAE2 is crisper and sharper, delivering more articulate detail. If you want detail to pop out more, the OAE2 is the better choice. If you want to lean a bit back and be enveloped in a smoother, more liquid delivery, the D1 is better.
While both have good dynamics, the OAE2 is stronger in terms of both macrodynamics and microdynamics, including the articulation of detail.
Instrument timbre is also a clear differentiator. The OAE2 is sharper, crisper, more textured, and drier sounding, while the D1 is smoother, more liquid, and a bit warmer.
CONCLUSION
The HEDDphone D1 and Grell OAE2 are both excellent headphones that perform at an equally high level overall. Both are tuned to sound neutral and natural, and are well suited for both studio use and audiophile music listening.
They are however not identical and each has some comparative advantages. The OAE2 is just slightly ahead in terms of dynamics, detail articulation, and most of all in terms of imaging and staging capabilities. The D1, on the other hand, tends to sound smoother and even more natural. In comparison, the OAE2 can sound a bit dry and crisp, not as smooth and subtle as the D1.
That said, they both represent some of the most significant headphone releases in recent years, and both come with my highest recommendation.
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