By aspect — in detail
Tonality
Contested · 10 srcSources split on what the JT9 is. The two measurement-led reviewers and Audio Rabbit Hole call it neutral, natural and free of obvious colouration — one bench names it the sub-$200 tonality of the year. Most of the listening reviews hear colour: warm and bassy with a moderately V-shaped balance (Headfonics, the Reddit owners, Ianbanz), or lively and slightly bright with a lifted presence region (PCMag). The graphs sit closer to the first camp; the second camp is describing the extension at both ends and the 2 kHz step-back as emphasis.
Measured
Three rigs agree on the shape from 40 Hz up: bass and lower mids within ~1 dB of 500 Hz, a ~1 dB bump near 1–1.2 kHz, a 3–4 dB step down at 2 kHz relative to the JT7 (Pragmatic Audio's KB501X and Jaytiss's B&K 5128 both show it), a ~12 dB ear-gain peak at 3 kHz that sits on target, and — on the 5128 — 5–8 kHz running 3.6–5.1 dB above a tilted diffuse-field target. DIY-Audio-Heaven's flatbed reads the treble 'on the correct level'; Pragmatic Audio scores the JT9 4.7 dB RMS from its tilted target across 1–8 kHz (JT7 4.8, Sundara 3.6).
⚠ vs. listeners — The graphs support 'neutral' below 2 kHz and 'a little extra air' above 5 kHz; 'V-shaped' is the combination of full sub-bass extension, the 2 kHz dip and that upper-treble energy heard as a smile. Nobody measures a bass shelf, so 'bassy' is extension without a hump.
Where it splits
Neutral and natural — no obvious colouration, a reference-grade tuning for the money.36%
“The sound is ‘natural’ and pleasant without any obvious colorations.”
DIY-Audio-Heaven (Solderdude)
Coloured and fun — warm, bassy and moderately V-shaped (or, to one reviewer, lively and bright).64%
“The JT9 has a warm, bassy, moderately V-shaped tonality with a larger-than-life sound presentation.”
Headfonics (Marcelo)
Everyone agrees the low end is the biggest change from the JT7 and that it extends deep and stays clean. They split on quantity and texture: one camp hears a genuinely bassy planar — dynamic-driver-like weight and sub-bass rumble that surprised them in an open-back — while the benches and PCMag hear neutral quantity: linear, no mid-bass hump, 'not a basshead set', and to DIY-Audio-Heaven a little soft and woolly rather than tight. The measurements side with the second camp on quantity and with the first on extension — on two of the three rigs.
Measured
No bass shelf on any rig — 40–200 Hz sits within ~1.3 dB of 500 Hz on both the KB501X and the B&K 5128. Extension is where the rigs disagree: DIY-Audio-Heaven reads 22 Hz at −3 dB and 'exceptionally seal-loss resistant'; Pragmatic Audio's KB501X has the JT9 within 1.7 dB of its 500 Hz level at 20 Hz, 4.2 dB above the JT7 and level with the Sundara's better channel; but on Jaytiss's 5128 the JT9 and JT7 roll off identically (about −7 dB at 20 Hz). Second-harmonic distortion peaks ~0.7 % at 20 Hz and stays under 0.2 % through the mids (PA); no compression up to ~95 dB SPL (DIY-AH).
⚠ vs. listeners — 'Prodigious bass' and 'bass heads will need more' are the same flat response heard against different references — most planars at this price roll off where the JT9 (on two rigs) doesn't, so full extension reads as generosity to some ears. The soft-vs-tight split has no measured correlate: distortion is low and the 40 Hz square wave is clean.
Where it splits
Generous for an open planar — weighty, deep, dynamic-driver-like bass that stays clean.46%
“There is a healthy amount of effortless low-bass presence, as if I’m listening to a dynamic-driver headphone, unlike most planar headphones, which have tight but stingy bass presence.”
Headfonics (Marcelo)
Neutral in quantity — deep and linear but not for bassheads, and a touch soft in texture.54%
“Bass levels will not satisfy bass heads but are not lacking and bass extension is good. Bass is a bit ‘soft’ in texture and does not ‘hit hard’ nor is it particularly ‘tight’ but of good tonality.”
DIY-Audio-Heaven (Solderdude)
Mids
Strong consensus · 10 srcBroadly praised — clear, textured, natural vocals with good note weight and no hollowness — and the point of least complaint. The only question is placement: Headfonics and Pragmatic Audio hear vocals take a small step back (the measured 2 kHz dip), PCMag hears a lift through the upper mids that makes female voices crisp and slightly forward, and everyone else hears them simply well balanced.
“Mids have good clarity and sound ‘realistic’, ‘dynamic’ and ‘open’ and ‘forward’.”
DIY-Audio-Heaven (Solderdude)
“It is audible if you listen for it, mostly as a small step back in the upper part of a vocal, but it never made a voice sound thin or hollow.”
Pragmatic Audio (Jerome O'Flaherty)
“There is a noticeable lift through the upper mids and presence region that gives vocals, sound effects and instruments a crisp and energetic edge.”
PCMag Middle East (Mufaddal Fakhruddin)
“Vocals through the JT9 are nicely detailed and have good saturation without becoming artificially aggressive.”
Head-Fi showcase review (cleg)
Measured
Both compensated rigs show a ~1 dB bump near 1–1.2 kHz that the JT7 lacks, then the JT9 sitting 3–4 dB below the JT7 at 2 kHz (Pragmatic Audio: about 3 dB under the JT7 and 5 dB under the Sundara there) before a ~12 dB ear-gain peak at 3 kHz that lands on target. DIY-Audio-Heaven's step response notes a small emphasis between 600 Hz and 1.2 kHz.
Treble
Strong consensus · 11 srcStrong agreement that the top end is smooth, extended and non-fatiguing — a clear improvement on the JT7 — with the character described as airy and energetic by some and calm and gentle by others. Nobody who reviewed a retail unit calls it harsh; Pragmatic Audio notes a pre-release sample sounded too forward and that FiiO toned it down, and cleg warns it won't hide brightness already in a recording.
“Treble is smooth and of high quality without any sharpness to it, well extended and on the correct level.”
DIY-Audio-Heaven (Solderdude)
“cymbals have energy without splashing, sibilance stays where it belongs, and I did not find glare on anything I played.”
Pragmatic Audio (Jerome O'Flaherty)
“There is plenty of sparkle and air, but it avoids the scratchy or brittle character that I tend to dislike in brighter headphones.”
PCMag Middle East (Mufaddal Fakhruddin)
“The JT9 isn't excessively sharp, but it also won't hide brightness already present in a recording.”
Head-Fi showcase review (cleg)
Measured
On Jaytiss's B&K 5128 the JT9 runs 3.6–5.1 dB above the tilted diffuse-field target across 5–8 kHz (a couple of dB above the JT7 at 5 and 7 kHz, below it at 6 kHz) with no narrow peak; DIY-Audio-Heaven's unsmoothed flatbed trace reads the treble at the correct level with extension past 30 kHz and only a 4 kHz resonance in the CSD. Above ~8 kHz every rig is dominated by coupler resonances.
Soundstage
Contested · 9 srcSources split on size. Headfonics, Audio Rabbit Hole, cleg, littlenezt and the owner reviews hear an unusually large, spherical, 'massive' stage for the price — the first thing most of them mention. Pragmatic Audio, PCMag, Ianbanz and EarVerdict hear something good but ordinary: natural, orderly, 'real but not extraordinary', and to Ianbanz outright intimate — a large room, not a hall. The split tracks reference: those coming from the JT7 or closed-backs hear big; those comparing to egg-cup HIFIMANs hear normal.
Where it splits
Unusually large and spherical for the money — the headline strength.53%
“JT9’s stage and soundscape are unusually large and way above average for its price.”
Headfonics (Marcelo)
Good but not big — natural, orderly, even intimate next to the wide HIFIMAN open-backs.47%
“I would call the large stage other reviewers report real but not extraordinary.”
Pragmatic Audio (Jerome O'Flaherty)
Sources split. PCMag (gaming-tested), Audio Rabbit Hole, Pragmatic Audio and the owner reviews call placement excellent, orderly and well separated; Headfonics names imaging the one thing it would improve ('not bad, just average'), DIY-Audio-Heaven says it is good but no better than comparable planars, and Ianbanz would not pick it for competitive positional gaming. Both camps agree separation holds up in busy mixes.
Measured
Channel matching is excellent on both rigs that publish it — DIY-Audio-Heaven calls it excellent for the price, and Jaytiss's 5128 left and right traces stay within 0.4 dB of each other from 20 Hz to 15 kHz (where the Sundara Pragmatic Audio measured splits by several dB at 20 Hz).
Where it splits
Fine but unremarkable — average placement, no better than its planar peers.39%
“Stereo imaging is good and not better than any of the other comparable planar headphones.”
DIY-Audio-Heaven (Solderdude)
Precise and orderly — excellent positional accuracy and separation for the price.61%
“What the JT9 does well is keep images focused and stay orderly when a recording gets busy, which is what FiiO said they were aiming at.”
Pragmatic Audio (Jerome O'Flaherty)
Detail
Strong consensus · 8 srcConsistently rated a clear step above the JT7 and strong for the price — resolving, textured, and separated — with the caveat, from Headfonics and PCMag, that it is not an analytical headphone: it can sound more detailed than it is because the presence region pushes information forward, and a Kithara reveals slightly finer texture.
“The JT9 is a clear step above the JT7 here.”
Head-Fi showcase review (Ianbanz)
“Detail retrieval is good, but the JT9 doesn't constantly flex its ability to reproduce microcontrast or push every tiny recording detail into your face.”
Head-Fi showcase review (cleg)
“That is worth keeping in mind, because the JT9 can sound more detailed simply because it puts so much information right in front of you.”
PCMag Middle East (Mufaddal Fakhruddin)
Dynamics
Strong consensus · 8 srcStrong agreement: fast, punchy and effortless, with real contrast between quiet and loud passages, and it goes very loud without distortion or compression — from a laptop, a dongle or a desktop amp. Several reviewers add that it still scales with more current. DIY-Audio-Heaven's one reservation is that the bass itself doesn't 'hit hard'.
“There is no compression up to about 95dB SPL.”
DIY-Audio-Heaven (Solderdude)
“Thanks to its large planar driver, I hear effortless dynamics, especially when paired with powerful sources.”
Headfonics (Marcelo)
“The JT9 is a surprisingly dynamic headphone.”
Head-Fi showcase review (Ianbanz)
Measured
DIY-Audio-Heaven measures 17 Ω and 115 dB/V (97 dB/mW) — 8 dB more sensitive than the JT7 — with no compression to ~95 dB SPL and only 0.5 dB at 32 Hz at 100 dB; ~2 mW reaches studio level and 200 mW gives 120 dB peaks. Pragmatic Audio's sweep at ~89 dB average / 100 dB peak keeps every harmonic ~45 dB below the fundamental.
Comfort
Contested · 10 srcSources split, four to one by weight. Most call it excellent — light for a planar, soft breathable pads, easy clamp, fine with glasses and big heads, hours without hot spots. A minority find the fit hit-and-miss: the oval opening is small enough that the pads sit partly on the ear, the clamp is so light the headphone can slide, and the headband can press on the crown. Ear size and head size decide which camp you land in.
Measured
365 g by FiiO's sheet, 374–375 g on DIY-Audio-Heaven's scale (JT7 318 g, Sundara 372 g). Clamp 2.5–3 N stock (DIY-AH bent his to 1.5 N); pad opening measured 60 × 45 mm and 25 mm deep by DIY-AH, ~65 × 45 mm and ~20 mm by cleg and ARH — shallower than the JT7. Ears run a little warm and the pads squeak against glasses (DIY-AH). FiiO's HS-FT1A/HS-FT1B pads fit and are deeper and softer, at the cost of a ~5 dB wide-band lift around 1 kHz.
Where it splits
Light, soft and all-day comfortable — one of the best fits at the price.80%
“The low weight makes the headphone quite comfortable.”
DIY-Audio-Heaven (Solderdude)
Hit-and-miss — small cups that sit on the ear, a too-light clamp, a headband that can press.20%
“The earcups are smaller than I would have liked, and rather than fully surrounding my ears, the cushions tend to sit partly around and partly on top of them.”
PCMag Middle East (Mufaddal Fakhruddin)
The sharpest split in the record. One camp — both benches, Headfonics, cleg, EarVerdict — calls it sensibly built for the money: steel headband, metal grilles, good plastic, nothing creaks, folds into a real case. The other — PCMag, Audio Rabbit Hole's first impression, and the Head-Fi/Reddit critics — finds it plasticky and creaky in hand and points at the JT7: the JT9 keeps the same headband and yokes that owners have reported cracking, with no visible reinforcement. Nobody has reported a JT9 failure yet; it is a month old.
Where it splits
Well built for the price — metal where it matters, sturdy, folds, comes with a hard case.56%
“For ($)€ 160.- you get a very comfortable and well built headphone.”
DIY-Audio-Heaven (Solderdude)
Plasticky and creaky — and it inherits the JT7 headband that owners have reported cracking.44%
“Give the headset a light shake and there is some creaking and plastic-on-plastic noise, almost as if something inside the construction is slightly loose.”
PCMag Middle East (Mufaddal Fakhruddin)
Isolation
Strong consensus · 5 srcOpen-back by design: essentially no isolation, and it leaks in both directions at any volume. Expected for the type, but several reviewers flag that the folding frame and case invite travel use the acoustics don't support.
“Of course, being an open-back headphone, it offers virtually no isolation and leaks plenty of sound in both directions”
PCMag Middle East (Mufaddal Fakhruddin)
“The only negative that I can find with this set is the sound bleed.”
Head-Fi showcase review (Dad Reviews)
Broad agreement that it is a bargain — several call it the best affordable planar or the sub-$200 headphone to buy, and one bench ranks it ahead of the JT7, FT1 Pro and Sundara. The reservations are about the ladder rather than the price: Pragmatic Audio docks a point because the JT7 does most of it for $50 less, and the build critics would rather pay a little more for the FT1 Pro's metal yokes.
“At this moment I would say the JT9 is the best choice for those wanting to get a taste of planar magnetic sound at an affordable price which is also ‘easy to drive’.”
DIY-Audio-Heaven (Solderdude)
“For $169.99, this level of sound quality is difficult to complain about.”
PCMag Middle East (Mufaddal Fakhruddin)
“Four for price, not five, only because it is $50 more than the JT7 and the JT7 is still a very good headphone”
Pragmatic Audio (Jerome O'Flaherty)
“i would rather spend more for the ft1 pro atleast it has a metal hinge and even if it fails its easy to repair”
Head-Fi launch thread (DGJM)
