By aspect — in detail
Broadly agreed: neutral and studio-honest, leaning slightly bright, with the classic Beyer treble spike tamed — flat through the low end and mids with a controlled high-frequency lift. Reviewers quibble on the last few degrees (some hear a hair of low-mid warmth, others a slightly lean presence region, one outlier calls it a mild V/U), but the underlying voicing they describe is the same, and it is far more even than the DT 990 it descends from.
“The sound of the DT 900 PRO X is almost flat but slightly bright.”
Cuckoo Studio (Anzol), via Audio Science Review
“PRO X proves to be the most neutral of the 3 with the flattest bass and mids and the least aggressive highs.”
Sonarworks (SoundID Reference)
Measured
Measures close to neutral: roughly flat 20 Hz–2 kHz, a small ~3 dB dip around 3–4 kHz, and a controlled +5–6 dB lift above 5 kHz (Cuckoo Studio) — the most neutral of the DT 990/1990/900 trio, with the flattest bass and mids and the 'least aggressive highs' (Sonarworks). Solderdude and Sound On Sound note a hair more low-mid warmth than the closed DT 700 PRO X / Sennheiser HD 400 PRO.
Agreed on the facts, split on taste. Sub-bass extension is excellent and reaches deep, but the level is neutral and un-boosted, so this is explicitly not a basshead headphone. Most hear it as tight, textured and 'true' — impressively present for an open back; a minority (and the leanest listeners) find it a little understated, and one measurement notes the very lowest octave is down a few dB.
“Subbass is reaching very deep.”
DIY-Audio-Heaven (solderdude)
“If anything their bass is a little understated; it prioritises agility, texture and control over outright power.”
What Hi-Fi?
Measured
Extension is essentially flat to 20 Hz at a neutral (not elevated) level with low distortion (DIY-Audio-Heaven: '20Hz = 0dB'); Sonarworks calls the sub-bass 'as good as it gets with open-back headphones' but measures the lowest frequencies down more than 5 dB, so the deepest sub-bass is present rather than emphasized — which is why bassheads are pointed elsewhere.
Mostly heard as neutral and un-recessed — clear, dynamic, with vocals sitting naturally centered — and defenders push back hard on the 'recessed mids' meme. But there is a small, measured presence dip around 3–4 kHz, and a subset (often coming from warmer Sennheisers) hears vocals and lead instruments as slightly pulled back or lean because of it.
“Sound wise, I certainly wouldn't agree with them having recessed mids, they don't have the usual beyer higher frequency bump and the lows have perfect representation which is strange for an open back.”
r/headphones (Far_Version_9043)
“the high mids get carved out progressively more and more until 4kHz.”
Sonarworks (SoundID Reference)
Measured
Flat lower mids with a gentle presence dip toward 4 kHz — Cuckoo Studio measures the 3–4 kHz attenuation as small (within ~3 dB); Sonarworks frames the same slope as high-mids 'carved out' progressively. The effect is subtle, and whether it reads as 'recessed vocals' or 'neutral' is partly a matter of what a listener is used to.
The headline disagreement. Everyone agrees Beyerdynamic tamed the old DT 990 spike; they split three ways on the result. One camp hears it as nicely smoothed and non-fatiguing with no real harshness; another still measures and hears a bright lift that can turn harsh or sibilant on some recordings; a third — often ex-DT 990 owners — finds it over-damped, missing the sparkle, even blunted or lifeless. The divide tracks treble sensitivity, the recording, and what you're coming from.
Measured
The lift is real but far tamer than the DT 990's: Cuckoo Studio measures +5–6 dB above 5 kHz ('very well controlled' vs the old Beyer); Sonarworks a boost from ~5–12 kHz; DIY-Audio-Heaven narrow dips/peaks above 8 kHz (an 11 kHz peak) that account for a slight 'coarse/grainy' quality, and notes the DT 990 runs ~5 dB hotter in the 6–9 kHz sibilance region.
⚠ vs. listeners — The tuning is measurably between the sharp old DT 990 and a fully relaxed can, so it lands differently by listener: treble-sensitive ears and bright recordings surface the residual lift as harshness, listeners used to the DT 990's sparkle hear the smoothing as blunted, and many others simply hear it as pleasantly even. Same graph, three verdicts.
Where it splits
Nicely tamed — smooth, detailed and non-fatiguing, with the old spike gone and no real harshness.42%
“the treble quality is not super refined but still quite good and maybe just a tiny bit elevated resulting in good detail and air but no sibilance/harshness.”
DIY-Audio-Heaven (solderdude)
Still bright — a residual high-frequency lift that can read harsh or sibilant on brighter material.36%
“distorted guitars can sound overly harsh”
Sonarworks (SoundID Reference)
Over-tamed — smoothed so far it loses the classic Beyer sparkle and can sound blunted or lifeless.22%
“it does kindof take away that sparkle the highs on the sound signature that people love or hate the 990s for.”
r/headphones (Tuned_Out)
Soundstage
Moderate · 7 srcA consistent strong point for an open back: spacious, open and well-organized, wide enough to be a repeated pick for competitive gaming. Reviewers frame it as believable and natural rather than artificially holographic, but the openness and sense of space are near-universally praised.
“Being open-back, the DT 900 PRO X deliver a spacious but realistic soundstage.”
Mobile Audiophile
“The Beyer dynamic DT 900 pro x has a great soundstage but has a more V/U tuning...which you'll either love or hate.”
r/headphones (Tuned_Out)
Measured
Presented as open and spacious with a natural front-to-back layout that community listeners rate highly for gaming (a 'full back, mid, and forward soundstage'); several owners contrast it favorably with the more intimate, forward stage of planar rivals like the Sundara.
Strong and precise — a favorite trait for gaming, where reviewers single out its directional accuracy, and a measured strength thanks to excellent channel matching. Placement is clean and stable, with a solid, well-anchored center image.
“I own both and I do think for gaming the 900 Pro X are better, especially for directional imaging.”
r/headphones (PointMoney)
“Channels are matched beautifully!”
Sonarworks (SoundID Reference)
Measured
Channel matching is among the best Sonarworks has measured (all but one test pair 'practically identical'), and Cuckoo Studio found 'no noticeable skew problems... which makes the center imaging solid' — a technical basis for the imaging praise.
A price-class strength: resolving, clean and free of smearing, and several reviewers rate its technical performance a notch above the HD 600 in the same bracket. The honest caveat is that it is not a flagship resolver — the pricier DT 1990 and good planars pull ahead for the most discerning listeners.
“The transient details of the song will not be smeared in any way.”
Cuckoo Studio (Anzol), via Audio Science Review
“the DT 900 PRO X has a relatively more solid actual listening feel compared to the HD600 in the same price range.”
Cuckoo Studio (Anzol), via Audio Science Review
Measured
Tied to the STELLAR.45 driver's low distortion and clean transients; solderdude places the DT 1990 (with its treble peak reduced) and a modded DT 880 above it for outright 'hyper detail,' framing the 900 PRO X as a strong price-class resolver rather than an absolute one.
Lively and composed: reviewers describe confident macro-dynamics and clean transients, with no sense of compression at normal listening levels. Not called a slam monster, but consistently praised as energetic and controlled for the type.
“these headphones render the sound with verve, punching out crescendos with confidence.”
What Hi-Fi?
“the distortion at 86 dB does not cause a sense of compression or sound contamination on the listening feel.”
Cuckoo Studio (Anzol), via Audio Science Review
Measured
Low distortion above ~100 Hz keeps things clean and uncompressed at listening levels (Cuckoo Studio, DIY-Audio-Heaven); solderdude describes an overall 'forward, open and dynamic' presentation.
Genuinely split, and it tracks head size and time. The plush velour pads, roomy cups and light weight win broad praise, and most reviewers call it an all-day headphone. But the clamp is firm out of the box (measured 5.3 N), and a real minority — smaller heads especially — find it too tight until it loosens over a couple of weeks, with one measurer getting a headache after an hour.
Measured
Weighs ~343–345 g without cable (moderate for the class) with replaceable velour pads and a spring-steel headband; DIY-Audio-Heaven measures the clamp at a high 5.3 N out of the box. Owners widely report it loosens over the first 2–3 weeks (or with box-stretching), which is why fresh-unit impressions of the clamp vary so much.
Where it splits
All-day comfortable — plush pads, well-judged fit, clamp is fine (and eases with use).62%
“I found both the Beyerdynamic models perfectly comfortable.”
Sound On Sound (Phil Ward)
Clamp too high — tight out of the box, hard on smaller heads or long sessions until it breaks in.38%
“The clamping force is on the high side and wearing it for more than an hour gives me a headache.”
DIY-Audio-Heaven (solderdude)
Build
Strong consensus · 8 srcA near-universal highlight. Metal and spring steel where rivals use plastic, made in Germany, with a detachable mini-XLR cable and replaceable pads, cable, headband and even drivers — reviewers place the overall quality closer to the premium DT 1990 than the old DT 990. The main asterisk is some early reports of headband padding wearing out, reportedly improved on later units.
“The Overall level of quality places them closer to the premium DT 1990 PRO than the entry-level DT 990 PRO.”
Sonarworks (SoundID Reference)
“the build quality of Beyerdynamics is rocksolid.”
r/headphones (DE4DLINK)
Measured
Spring-steel headband with metal-and-plastic cups, a locking 3-pin mini-XLR detachable cable (two lengths, no balanced option) and fully replaceable pads/cable/drivers; Sound On Sound highlights the European manufacture and metal construction. DIY-Audio-Heaven relays early complaints of headband padding failing, which community owners say newer revisions addressed.
Isolation
Strong consensus · 4 srcOpen-back by design: essentially no passive isolation, and it leaks freely both ways. Expected for the type and not treated as a flaw — but it rules out offices, commutes and shared rooms.
“It is an open headphone so outside noised are not attenuated much and people around you will clearly hear what you are listening to.”
DIY-Audio-Heaven (solderdude)
Measured
Fully open-back — no isolation and free leakage in both directions, by design; every source treats it as an open headphone.
Widely called a strong buy in the ~$270–300 open-back class — praised as the best value among its direct rivals and a legitimate alternative to the classic HD 600, with the made-in-Germany repairability adding long-term worth. The asterisk: for pure music, some listeners still prefer a Sundara or HD 6XX, and it is a studio tool first.
“As a whole, DT 900 PRO X offers the best value among its direct rivals.”
Sonarworks (SoundID Reference)
“This makes it a top choice for headphones in the 150-300 USD price range, and it can also compete with the classic HD600 headphones in the same price range.”
Cuckoo Studio (Anzol), via Audio Science Review
Measured
Launched around $299 (≈£219 / €230–250) and now listed around $319.99 by Beyerdynamic, with street pricing typically in the high-$200s to ~$320; the fully repairable, made-in-Germany construction and no-amp-needed drivability factor into the value case, though pure-music listeners cross-shop the Sundara and HD 6XX at similar money.
