HeadphoneOverreview

Audio-Technica ATH-M40x

Name: Audio-Technica ATH-M40x
Brand: Audio-Technica

The 'flat' M-series pick a decade of buyers trusted — and the graphs find it about as bassy as the M50x.

39 sourcesUpdated 2026-10-12

$109Typical US price

Score aggregates reviewer opinions across topics.

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The short version

What to know.

A light, easy-to-drive closed-back that most listeners hear as balanced and most measurement rigs show is not flat. Every rig finds the same shape: a mid-bass shelf around 2.5–6 dB over target between 80 and 250 Hz, a midrange that stays close to neutral, and a lift above 8 kHz. Against the M50x on four shared rigs the bass is about equal or higher, and on two the top octave is clearly higher, so the 'flatter sibling' reputation describes a different balance more than less colour. Reviewers broadly agree it is easy to drive, has a narrow stage, and has clear, slightly lean mids. Opinion splits six ways: balanced versus coloured tonality (roughly two to one balanced); bass that is a muddy hump, about right, or too light; treble that is clean or hot and artificial; comfort, where the clamp and shallow pads divide people; build, where a tough reputation runs into a long record of cracked hinges and flaking pads; and isolation, which reviewers call poor while owners mostly find it adequate. It remains a well-liked hundred-dollar headphone, with the AKG K361/K371 the rival critics keep naming.

About this product

The 40 mm, 35 Ω closed-back monitor launched in 2014 alongside the 45 mm ATH-M50x, with the same twist-locking detachable cable system (a coiled and a straight cable in the box). Not the M50x above it, nor the M30x / M20x below it; there is no Bluetooth M40x (the wireless M-series options are the M50xBT2 and M20xBT).

Audio-Technica's ATH-M40x arrived in 2014 as the plainer, cheaper sibling of the ATH-M50x and has been recommended ever since for one specific reason: it is supposed to be the flatter one — the hundred-dollar closed-back you can track and mix on, where the M50x went to commuters and DJ booths.

That reputation is what this record tests. It draws on 39 sources — nine measurement rigs and labs, the full eleven-review Head-Fi showcase and its 47-page owners' thread, three video reviewers, eleven Reddit and ASR arguments, and roughly 17,000 Amazon and 900 Thomann owners — and they agree on less than the reputation suggests. Most listeners call it balanced; the graphs show a real mid-bass shelf and a lifted top octave; and the people who have owned one for years talk mostly about the hinge, the clamp and the pads.

A good fit for

Home-studio tracking and mixing on a budget, if you know its bass shelf and treble lift and check mixes elsewhere
Phone, laptop and audio-interface users who want a closed-back that needs no amp
Anyone who wants the M-series look and detachable cable at a lower price than the M50x
Listeners with small-to-average ears who find a firm clamp secure rather than tiring
Owners happy to swap pads, who can tune the comfort and the bass with them

Think twice if

You want a genuinely flat reference — on the graphs it is about as bassy as the M50x, with a lifted top octave
You're treble-sensitive — the lift above 8 kHz is the most common sound complaint
You have large ears, wear glasses, or need all-day comfort — the pads are shallow and the clamp is firm
You're rough on gear or travel a lot — the plastic hinge is the documented failure point
You need strong isolation for tracking near a loud source or for flights
You'd rather have the AKG K361/K371 or Beyerdynamic DT 240 Pro, which critics name at the same money

The reviewer consensus

Agreement &
disagreement.

6 / 12topics divide opinion

6 Mostly agree6 Divided opinions

Common ground6

It's easy to drive: 35–38 Ω and sensitive enough to play loud from a phone or laptop with no amp.
The midrange is clear — vocals come through cleanly, even if a few listeners find guitars a little thin.
The soundstage is narrow, as expected for a small sealed cup.
The detachable twist-lock cable is a real longevity win, though it uses a locking 2.5 mm connector rather than a plain jack.
Every rig that measured it shows a mid-bass shelf over target, and the four that also measured the M50x find about as much bass in the M40x, not less.
Pads change it a lot: aftermarket pads fix comfort for many owners but shift the bass and treble by several dB.

Points of contention6

Tonality: 'balanced enough to monitor on' (about two-thirds of the weight) vs 'coloured, and only flat next to the M50x' — the graphs back the second camp's shape but not the M50x comparison.
Bass: an overemphasised upper-bass hump that muddies (57 %) vs controlled and about right (30 %) vs too light for bass lovers (13 %).
Treble: hot, peaky or artificial vs clean and detailed — rigs disagree on the size of the lift above 8 kHz.
Comfort: light and fine for hours vs hard clamp and shallow pads that hurt within an hour or two — it tracks head and ear size.
Build: sturdy and drop-tolerant vs a plastic hinge that cracks and pads that flake.
Isolation: reviewers call it poor for a closed back; owners mostly find it fine for a room or a commute.

A closer listen.

12 topics · 6 divided

Left: criticalRight: positiveTighter lines: more agreement

Choose a topic

Tonality

Leans positiveDivided opinions

Reviewer sentiment25 supporting sources

CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

Sources split on whether it is the neutral studio reference its reputation promises. About two-thirds of the weight — Crinacle's tone grade, RTINGS' verdict, SoundGuys, Higher Hz, Podcastage, Z Reviews and most Head-Fi reviewers — hear it as balanced, flat enough for monitoring, and more even than the M50x. A third — DIY-Audio-Heaven, Sonarworks, Home DJ Studio, DMS and the Head-Fi thread that asked why people call it the accurate one — hear a coloured, mildly V-shaped tuning that only looks flat next to the M50x. The measurements side with the second camp on the shape and with neither on the sibling comparison: the M40x is not less bassy than the M50x and, on two rigs, is brighter.

Measured

Five rigs agree on the shape. Against their targets the 80–250 Hz band sits +4.8 dB (oratory1990, GRAS), +5.4 dB (RTINGS) and +2.5 dB (Auriculares Argentina); against the HD 600 on the same rig it is +4.4 dB (oratory1990) and +3.6 dB (Crinacle). The midrange stays within about 2 dB of target, and the 8–11 kHz band runs +3.6 to +9.3 dB high on every rig but headphones.com's listener database, which reads the treble 3–4 dB under its KEMAR target and the bass 6–9 dB over. Against the M50x on the same rig the bass is within about 1–2 dB (and higher on the listener rig), while 8–11 kHz is 5.7 dB higher on oratory1990's and about 8 dB higher on Crinacle's. Sonarworks calls the shape a W-curve and scores its frequency response 4/10.

vs. listeners — The flatter-than-the-M50x reputation doesn't survive the graphs — the two carry similar bass, and two rigs give the M40x clearly more top octave. What listeners may be hearing is a different balance: the M50x's treble dips where the M40x's lifts, so the M40x sounds clearer and less bass-dominated without having less bass. Both camps can be right about what they hear.

Where it splits

Balanced enough to monitor on — the even-handed M-series model.67%

“Well-balanced tonality with disappointing detailing and claustrophobic imaging.”
Crinacle (headphone ranking list)

Coloured, not flat — a mid-bass shelf and lifted treble that only look neutral beside the M50x.33%

“It is lacking a bit in tonal accuracy when used for music enjoyment.”
DIY-Audio-Heaven (solderdude)

Link to this topic

Bass

Leans criticalDivided opinions

Reviewer sentiment25 supporting sources

CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

Sources split three ways over the same mid-bass shelf. The largest group — RTINGS, DIY-Audio-Heaven, Sonarworks, Higher Hz, several Head-Fi and Reddit owners — hears an overemphasised upper bass that thickens and muddies busy mixes. A smaller group — SoundGuys, Podcastage, Home DJ Studio, Z Reviews — hears it as controlled and well judged: present but not masking anything. And a minority, mostly people who wanted bass, find it light and polite. The split tracks expectations and pads more than ears: the hump sits at 80–250 Hz rather than in the sub-bass, and aftermarket pads move it by several dB.

Measured

80–250 Hz sits 2.5–6 dB over target on every rig, with the lowest octave close to target rather than rolled off (oratory1990 −1.1 dB at 20–40 Hz). DIY-Audio-Heaven measures bass distortion below 1 %, while Sonarworks scores harmonic distortion 4/10 and singles out odd-order distortion in the lows. CammyFi's pad-swap measurements show how pad-dependent it is: the same unit reads +4.5 dB over the HD 600 at 80–250 Hz on M50X pads and −2 dB on Brainwavz pads.

vs. listeners — SoundGuys' studio target is itself bass-heavy, so on its chart the M40x looks restrained, while on Harman-style and diffuse-field targets the same bass reads as a hump. And the 'too light' reports come from bass-forward listeners: on the graphs the M40x's bass is about level with the M50x's.

Where it splits

An overemphasised upper-bass hump that thickens and muddies.57%

“The Audio-Technica, on the other hand, have an overemphasized bass, particularly in the high-bass range, which can make them sound muddier.”
RTINGS

Controlled and about right — present without masking the rest of the mix.30%

“Although many people prefer a bass-heavy sound, this more subdued response is good for songs with a range of instruments because nothing is at risk of serious auditory masking.”
SoundGuys (Lil Katz)

Too light — polite and punchless for anyone who came for bass.13%

“Can be boring for those who want more bass/more fun signature.”
baskingshark (Head-Fi review, 3★)

Link to this topic

The hardware

Specifications.

Checked 2026-10-12

Design

Type: Closed-back
Drivers: 1 × 40 mm dynamic

Electrical

Impedance: 35 Ω
Frequency response: 15 Hz – 24 kHz

Connection

Cable: Detachable
Connector: 2.5 mmcommunity-sourced
Plugs supplied: 3.5 mmcommunity-sourced

Physical

Weight: 240 g

Manufacturer-published figures, not measurements · from audio-technica.com. Connector, plugs supplied not published by the maker — community-sourced from hands-on reviews: diyaudioheaven.wordpress.com, head-fi.org, soundguys.com.

Follow the evidence

Sources 39

Read with context

Limitations & method.

As of 2026-10-12

What to keep in mind 7

This is a read of where opinion and measurements stand in October 2026. The M40x itself hasn't changed since 2014, but the field around it has — the AKG K361 and K371 in particular reset what a hundred dollars buys in a closed-back.
Its reputation as the 'flatter' M-series model is mostly a listening impression. Measured side by side, it carries about as much bass as the M50x, and on some rigs more treble, so it's worth knowing which kind of review you're reading.
Treble readings vary more than usual between test rigs, and the lift sits where ear shape and seal matter most — some people will hear it as clean, others as sharp.
Comfort and isolation depend heavily on your head: the pads are shallow and the clamp is firm, so fit decides both how long you can wear it and how well it seals.
Measured units haven't always matched left to right. If you buy one, check that a centred voice sits in the middle while you can still return it.
Many of the warmest reviews were written after a pad swap. On stock pads it sounds and fits differently, and thicker aftermarket pads can stress the hinges.
The big owner-rating averages come from people who chose to buy it, so they skew positive — and the same owners rate its durability and comfort much lower than its sound.

Where to buy Product & retailer links

Audio-Technica ATH-M40x Amazon

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