By aspect — in detail
Most sources hear a full, punchy, mid-bass-forward low end — the thing several call its best feature — while a smaller group hears a polite, supportive bass with restrained sub-bass. Nearly everyone on both sides agrees the emphasis is mid-bass rather than sub-bass, that it stays clean of the mids, and that it never reaches basshead territory. The measurements complicate the language: there is no mid-bass hump and no roll-off.
“The bass is fuller than many listeners might expect from an open-back headphone. There is a clear mid-bass emphasis”
Goh Beng Yeow, Porta-Fi
“It's got a thick and heavy slam to it, more midbass than subbass focused.”
u/cl0ckw0rkaut0mat0n, r/headphones
“Overall, the bass performance is just average at best.”
DestinoAzell, Head-Fi showcase review
“EDM 계열에서는 다소 맥이 빠집니다. 이는 저역의 양감이 부족한 것이 가장 큰 영향을 줍니다.”
그리피스의꿈, Naver blog
Measured
Flat with no shelf on both rigs: 20 Hz sits within 0.5 dB (Elrics 711/KB50xx, five seatings) and 1.5 dB (Passion for Sound B&K 5128) of 500 Hz — 2–3 dB under a tilted diffuse-field target and about 5 dB under Harman 2018 in the bottom two octaves, but 7.8 dB above an HD 600 at 20 Hz on the same 711 rig and level with an HD 660S2 on the same 5128. 150–300 Hz is only 0.5–1.2 dB over target.
⚠ vs. listeners — Listeners describe a mid-bass emphasis and a restrained sub-bass; neither rig shows a mid-bass hump, and both show full extension. The 'punch' is the 1–2 kHz recession letting the upper bass and lower mids stand forward, and the 'restrained sub-bass' is the absence of a shelf rather than roll-off — which is also why the same graph reads as 'not warm' to graph-readers and 'very warm' to listeners.
Praised almost everywhere as the heart of the headphone: warm, natural, full-bodied vocals with no harshness, and the reason jazz, singer-songwriter and classic-rock recordings come up again and again. The dissent is a 'slight veil' — three sources hear vocals sitting a step back with less upper-mid presence than a Meze 109 Pro or an Audeze LCD-2 Classic, and one reviewer hears male voices as full yet subtly scooped. The graph backs the dissenters on where the dip is; the majority simply likes it.
“The midrange is the Mortise’s most persuasive region. Vocals are warm, natural, and well-proportioned.”
Goh Beng Yeow, Porta-Fi
“Vocals became a major strength as listening continued.”
Frankie D, Head-Fi showcase review
“What I do hear though is a very very slight veil over the vocals.”
Sweet2K, Head-Fi impressions thread
“have a bit less upper mid-range presence than the 2C, which can leave vocals sounding a bit veiled in comparison on some tracks”
michael2v, Head-Fi impressions thread
Measured
The largest deviation on both rigs is 1–2 kHz: 1.5 kHz sits 5–5.5 dB (Elrics) and 6.3–6.7 dB (PFS 5128) under target and 2 kHz 3–4 dB under, on both channels; the 2.5–3 kHz ear-gain peak then lands within about 1.5 dB of target.
Smooth, relaxed and sibilance-free for most — several call it the reason they can wear it all day, and two owners describe treble-sensitive relief. A minority hears the cost: cymbals and bells that lack bite or ring 'plastic', a phone that sounds less like metal. A separate small minority hears the opposite — a strident ride cymbal in a jazz mix, occasional sibilance on Freddie Mercury, some shout at high volume. The graph makes both complaints plausible at once.
“Still, the top end is not especially vivid. Sparkle is restrained, transient edges are rounded, and the finest details are not pushed forward.”
Goh Beng Yeow, Porta-Fi
“The highs are slightly rolled off in comparison to the 109Pros.”
Sweet2K, Head-Fi impressions thread
“the ride cymbal in particular coming off more stridently in the mix”
Stephen Kostas, Bloom Audio
“두누 모티스는 고역 어딘가에서 치찰음이 종종 들립니다.”
그리피스의꿈, Naver blog
Measured
3.5–7 kHz runs 4–9 dB under target on both rigs (4 kHz −5.6 dB on the 5128 and −8.9 dB on the 711 average; 6 kHz −7 to −10 dB), 8 kHz returns to target, and there is a 10 kHz notch of 2–8 dB on the seating averages (up to 16 dB on a single seating).
⚠ vs. listeners — A headphone this recessed from 3.5 to 7 kHz should not sound sharp — yet the one upper band that is not recessed is 8 kHz, the sibilance region, so 'smooth overall' and 'the occasional hot consonant or ride cymbal' are the same curve heard on different recordings.
Tonality
Contested · 21 srcSources split on how to name the same tuning. The larger camp — most of the English-language reviewers and owners — hears a warm, lush, relaxed coloration in the HD 650 / Meze 109 Pro family, a few going as far as 'vintage bookshelf speaker'. The smaller camp — the Chinese and Korean editorial reads, the retailer shootout and two owners — hears something closer to neutral: clean, modern, 'hard to call warm or cold', balanced with a midrange focus. Both are describing a graph with no bass lift and a recessed 1–2 kHz and 3.5–7 kHz; the warmth is an absence of edge rather than added low end.
Measured
Neither rig shows a bass shelf or a lower-mid hump; the tilt comes from 1–2 kHz sitting 4–7 dB under target and 3.5–7 kHz 4–9 dB under it, with 2.5–3 kHz and 8 kHz on target. Against Harman 2018 it is 4–5 dB short at 20–50 Hz and 3–5 dB short at 1.5–4 kHz — a dark tilt, not a bassy one.
Where it splits
warm, lush and relaxed — an HD 650-style coloration68%
“The Mortise has a warm, smooth, and full-bodied presentation.”
Goh Beng Yeow, Porta-Fi
closer to neutral — clean and modern, the warmth is the missing edge32%
“虽然很难说偏暖偏冷（因为也与前端关系密切），但是的确这个染色的存在会让它听上去不会那么“严肃”。”
KingTsui, TDS Studio
Soundstage
Contested · 16 srcSources split. The larger camp calls the stage wide, spacious and open for the class — one Chinese reviewer found it 'quite surprising', a Head-Fi reviewer 'noticeably wider' than an HD 660S2, an owner 'neck and neck' with a Meze 109 Pro. The other camp, including the retailer shootout and two of the more critical reviews, hears an intimate, front-row presentation with depth rather than width. Two of the intimate votes are conditional: the stage 'opens up' with more power, and it 'rolls off a little quicker' than more expensive headphones.
Where it splits
intimate — depth and center image over width37%
“a more intimate musical experience with classic rock, jazz, and recordings that prominently feature acoustic instruments”
Stephen Kostas, Bloom Audio
Generally rated solid to very good: a strong centre image, clean left–right placement and, for several, layering that outperforms warmer headphones at the price. Separation is the softer point — one reviewer finds instruments sitting close together and blurring on busy tracks, and the retailer shootout ranks it behind the Grell OAE2.
“Imaging is solid, with good left-right separation and an excellent center image”
Frankie D, Head-Fi showcase review
“악기의 정위감이 상당히 뛰어납니다.”
그리피스의꿈, Naver blog
“INSTRUMENT SEPARATION is not its forte.”
DestinoAzell, Head-Fi showcase review
Sources split. The larger camp treats resolution as adequate and beside the point — 'musical rather than technical', 'macros over micros', warmth that 'covers up some microdetails', a 7/10 for sound from one Head-Fi reviewer. The other camp hears a headphone that quietly resolves above its class: better than an HD 650 or DT 900 Pro X for the Chinese bench, string-buzz detail for the Korean blog, 'very detailed' with zero sibilance for one video reviewer. The split tracks what each reviewer compares it to — planars and reference sets on one side, the Sennheiser HD 6-series on the other.
Where it splits
musical first — resolution is merely adequate62%
“The Mortise is not the most incisive or transparent headphone in its class. Its technical performance is solid rather than spectacular”
Goh Beng Yeow, Porta-Fi
quietly resolving — outdoes the HD 650 class38%
“解析能力明显要比 HD650、DT 900 PRO X 之类一两千热门产品要好”
KingTsui, TDS Studio
Dynamics
Moderate · 16 srcMostly praised — punchy, tactile mid-bass, snappy drums, 'more punchy and dynamic' than an LCD-2 Classic for one owner — with a minority hearing restraint: flow over slam, reserved vocal dynamics, softness on the attack. The real argument is power. Several sources say it needs far more than its 38 Ω / 98 dB rating implies, that dongles leave the bass empty and the stage closed, and that it scales with a desktop amp; an equal number call it easy to drive from anything.
“动态出色，瞬态良好。”
KingTsui, TDS Studio
“In many ways it is an even more punchy and dynamic headphone”
michael2v, Head-Fi impressions thread
“Dynamics are restrained in favor of a smooth, effortless flow”
bigbeans, Head-Fi showcase review
“임피던스가 38오옴이지만 이상하리만큼 볼룸을 많이 먹습니다.”
그리피스의꿈, Naver blog
Measured
Rated 38 Ω and 98 dB/mW (113 dB/Vrms) by the maker — on paper an easy load; no independent sensitivity or impedance sweep was found.
The single most-agreed-on strength: light for a wooden headphone at 325 g, gentle clamp, a wide suspension strap with no hotspot, and pads that clear the ear — multiple sources report four- to six-hour sessions and two call it the most comfortable headphone they own. The dissent comes from the cups not swivelling: two listeners feel pressure behind the ears from the thick-at-the-back pads, and one owner notes the ear pads' chemical smell out of the box.
“It is extremely comfy as if I am not wearing it.”
DestinoAzell, Head-Fi showcase review
“I comfortably reached six continuous hours across multiple days”
bigbeans, Head-Fi showcase review
“Due to the design of the pads and the lack of swivel, I feel more pressure behind my ears.”
Richard M., Bloom Audio owner review
“After about fifteen minutes I became somewhat aware of the headphone’s presence, particularly behind the ears”
Frankie D, Head-Fi showcase review
Near-unanimous praise: solid walnut cups finished cleanly, metal everywhere else, a Dan Clark-style wire suspension, and a fabric-sheathed single-crystal copper cable with swappable 3.5/4.4 plugs and a hard case that several reviewers say embarrass headphones costing several times more. The caveats: no cup swivel, pads that are not built for easy swapping, one owner's ear-pad odour, and one reviewer who found the stock cable veiled and recommends replacing it — a claim no one else makes.
“The DUNU Mortise demonstrates exceptional build quality.”
bigbeans, Head-Fi showcase review
“they honestly feel comparable to Meze stuff”
u/cl0ckw0rkaut0mat0n, r/headphones
“Only questionable design decision regarding build is there's no front/back cup swivel mechanism.”
Carbon44, Head-Fi impressions thread
“The Smell off the Earcups ruins the first time Experience”
u/someonefrom77, r/headphones
Isolation
Moderate · 6 srcOpen-back by design, so isolation is not a scored strength: reviewers hear the kettle and the conversation. The nuance is that it is a slightly less open design than an HD 600 — the Chinese bench places it between a true open-back and a DT 880-style semi-open, and two listeners note it leaks less than planar headphones.
“Being an open back design, isolation is essentially non-existent.”
Scubadevils, Head-Fi showcase review
“它的开放程度要比 HD600、R70x、MV1 这类显得稍小一点”
KingTsui, TDS Studio
Widely called a bargain at $429.99 — several reviewers expected a $700–1,000 price after handling it, and the build, case and cable carry most of that argument. The dissent is about sound per dollar: one Head-Fi reviewer scores the sonics 7/10 and an Edition XS the better pure-sound buy, one owner thinks it should settle at €300, one Reddit owner says a Meze 109 Pro 'blows them away', and the Korean blog cannot recommend it to anyone driving it from a dongle.
“At $429.99, based on performance, build, accessories, and overall quality, Mortise is an absolute bargain”
Scubadevils, Head-Fi showcase review
“At $430, the sonic performance it gives is just average.”
DestinoAzell, Head-Fi showcase review
“They weren't bad...but the 109 blows them away.”
u/Needlecrash, r/headphones
