HEDD Audio HEDDphone D1

Broadly praised for how far it extends for an open dynamic headphone: clean, fast and well short of boomy, and clearly deeper than an HD 600. The quantity is the open question. Most sources hear it as just right, but a meaningful minority — including RTINGS and Resolve — find it lean against a Harman-style target and add a bass shelf, which the driver takes well.

“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.”

headphones.com (Griffin Silver, 'listener')

“compared to them, the HEDDphone D1 still feels a tad tame.”

Kuulokenurkka (Sword of Damocles), on the D1 against the Focal Hadenys and Austrian Audio Arranger

The headline strength: a linear, natural midrange that reviewers set beside the HD 600 and HD 650 — level with them for most, ahead for some. The dissent is about the 3 kHz ear-gain region, which a few owners and Twister6 hear as a little shouty at high volume or on hot recordings, and which RTINGS reads as slightly subdued against an HD 6XX.

“HEDDphone D1’s midrange is among the most linear midrange tunings you can find in over-ear headphones, regardless of price.”

headphones.com (Griffin Silver, 'listener')

“The forward-reproducing and extremely natural midrange is the D1's best feature”

Kuulokenurkka (Sword of Damocles)

“that exact 3 kHz peak pushes about 1.5–2.5 dB past what my personal HRTF agrees with, which explains why the D1 can occasionally come across as slightly shouty at louder listening volumes”

Twister6

Sources split, roughly three to one. Most reviewers hear controlled, well-extended treble that adds detail without sharpness or fatigue. A minority hear a peak, at 5 kHz or around 10–11 kHz depending on the head, that makes cymbals and sibilants tizzy and some sessions tiring. A few others call the top end slightly dark. The split tracks fit: clamp, earcup position and pad wear all move this region by several dB.

Near-universal agreement that it is one of the most neutral open-backs at its price — HD 600-like with deeper bass. The only disagreement is whether that neutrality is a virtue. A small group of owners hears it as clinical or analytical, and one reviewer hears a mild V-shape rather than flat.

“Tonality‑wise the HEDDphone D1s are impressively neutral, in fact, with no part of the spectrum sounding over‑ or under‑represented.”

Sound On Sound (Chris Korff)

“I think it’s definitely analytical on the brink of being clinical for a lot of people.”

jfleysh (Head-Fi)

“This tends to give them an ever so slightly V-Shaped presentation.”

Audiophile Heaven

Agreement on the shape of it: wider, more even and less 'three-blob' than an HD 600, but intimate rather than big. Several reviewers say depth is where it falls short, and Headfonics and Kuulokenurkka list the small stage as a con.

“The D1’s soundstage is wider and more three-dimensional than the HD600, which by comparison can feel like a three-blob presentation.”

Pragmatic Audio (Jerome O'Flaherty)

“The headphones reproduce sound close and present, quite similarly to the Sennheiser HD 600 & HD 650.”

Kuulokenurkka (Sword of Damocles)

“The width is actually still pretty fine for its price it’s the depth that noticeably falls short.”

Twister6

Consistently called precise and stable, with excellent separation. RTINGS measured no audible stereo mismatch.

“I also got a sense that the image was more precise than on the AKG models”

Sound On Sound (Chris Korff)

“The soundstage feels open, and the imaging is precise.”

The Headphoneer

Widely praised as resolving, with low-level detail that reviewers hadn't heard in familiar tracks. A minority — Kuulokenurkka and a few owners coming from pricier headphones — say it is clean rather than exceptionally transparent.

“the HEDDPhone D1s deliver incredible levels of detail.”

AVForums (Tim Hancock)

“However, if I consider the feeling of detail in the reproduction, I have heard more impressive headphones.”

Kuulokenurkka (Sword of Damocles)

Agreement that it is punchier and livelier than the HD 6X0 series, with a sharp 'thwack' on drums. Distortion stays low enough that it takes a large bass boost cleanly.

“despite not being overly colored, the sound of the HEDDphone D1 is surprisingly lively and expressive.”

Ear Fidelity (Mateusz Chmura)

“It has a more precise “thwack” on snare drums”

headphones.com (Griffin Silver, 'listener'), against the HD 600

Sources split almost evenly, and the split is the headband. The pads, the 350 g weight and the gentle-to-firm clamp are widely liked, and many reviewers wore it for hours. But the head pad is stiff, hard foam with no suspension strap, and on many heads it makes a hot spot within 15–60 minutes. Several owners returned it for that, while many others fitted a Capra strap or bent the arms to move the pressure. Narrow-ish ear openings bother a few.

Sources split, mostly positive. Reviewers praise a plain, solid build in which every part is replaceable with a screwdriver, backed by a five-year warranty. Owners add the long-term record. Many report a strong chemical or smoky smell out of the box that took days to weeks to fade, and it drove at least two returns. Some units developed creaking or clicking yokes, one owner's yoke hinge snapped (repaired under warranty), and the velour attracts lint.

An open-back, but several reviewers note it leaks and admits less sound than typical open designs. Audiophile Heaven still hears it leak at loud volumes.

“the D1s offer more isolation than you’d expect from open‑back headphones.”

Sound On Sound (Chris Korff)

“it leaks your music in loud volumes.”

Audiophile Heaven

Sources split almost evenly. Reviewers call it the overdue 'HD 600 upgrade' at a fair price, made in Germany with a five-year warranty. Many owners and skeptics answer that it is not almost twice as good as an HD 600 or HD 550, and several name $400–500 as the right price. Backorders of up to three months and the single, unbalanced stock cable weigh on it too.