Audio-Technica ATH-M40x

The defining argument, and it splits by evidence rather than by taste. One camp — mostly sources describing what they heard — holds that the M40x is the flatter, less coloured, more mix-appropriate sibling, which is the entire reason it gets recommended. The other — mostly sources reading graphs — finds the gap to the M50x much narrower than the reputation implies and the M40x itself well short of neutral: a gentle scoop through the lower mids with a mid-bass rise and an upper-treble lift, a shape Sonarworks calls a W-curve. Notably, nobody in either camp calls it actually flat.

Everyone sees the same low end and reaches opposite verdicts, because the M40x is lifted in the mid-bass while giving up sub-bass. To studio-leaning reviewers that restraint is the point — nothing masks anything. To others the 100–250 Hz rise is bloat that muddies the music. The most revealing case is the third group: bass-forward listeners who bought it expecting the M50x's reputation and found it gutless, which is the same restraint reported with the sign flipped.

The M40x's calling card, and the one thing near-everyone grants it. The measured dip through the lower midrange reads to most listeners not as recession but as clarity: forward, clean vocals that cut. It's what separates it from the warmer M50x, and even sources hostile to the rest of the tuning tend to call the midrange fine. The cost is a thinner presentation — the same scoop takes body out of guitars and mid-heavy material.

“This gives voices a ‘clear’ sound and because the FR drops off above 2kHz there is no ‘shrill’ sound.”

DIY-Audio-Heaven (solderdude)

“Upper midrange notes are clear and accurate, and lower voices come through well thanks to the modest boost from 100-200Hz.”

SoundGuys (Lil Katz)

Sources agree there's a lift up top and split on what it does. A minority hear clean, pleasant emphasis that pulls detail forward. The larger group — and, tellingly, both independent measurement houses arrive here separately — hear it as artificial: a top-end boost that mimics resolution rather than resolving, described as metallic, essy or 'fake detail'. Treble-sensitive listeners report real sharpness.

Narrow, as sealed closed-backs tend to be, and not a reason to buy it. Reviewers who raise it call the stage small and expected rather than a flaw; the rivals most often named at the price (the AKG K361/K371) are said to do a little better here.

“They don't have much soundstage because of their closed-back design, but their well-balanced sound will still satisfy most listeners.”

RTINGS

“The K361 is the same price and has a bit better soundstage”

Reddit r/HeadphoneAdvice

Generally a strength — instrument separation and left-to-right placement come in for praise, and it's part of why the M40x survives as a mixing recommendation. The complication is channel matching, where the two measurement houses flatly contradict each other, which points at unit variation rather than a settled answer.

“The channel matching on the ATH-M40x outdoes the ATH-M50x, as it doesn’t have an imbalance in lower mids and bass.”

Sonarworks (Rudi)

“4 dB difference in the 100Hz-400Hz region is a bit strange.”

DIY-Audio-Heaven (solderdude)

Reads as detailed for a hundred dollars, and reviewers reach for words like clear and resolving — but there's a persistent caveat that much of the impression is manufactured by the upper-treble lift rather than genuine retrieval. The midrange clarity is the part nobody disputes.

“The boosted treble will impart the sound with fake detail and will emphasize overtones on just about every instrument.”

Sonarworks (Rudi)

“Detailed imaging and fairly flat response.”

Higher Hz (Brandon Schock)

Easy to drive and undemanding: around 35–38 Ω with generous sensitivity, so it reaches full volume from a laptop or phone without an amp. No source argues it needs one, and nobody reports running out of headroom.

“The M40x with its 35Ohm impedance and generous sensitivity can be easily driven from any headphone output out there.”

Sonarworks (Rudi)

Genuinely split, and it tracks your head. One camp finds the clamp manageable and wears it for hours; the other finds it clamps hard, with firm, shallow pleather pads that press on the ears, sweat, and turn into a headache after a couple of hours. Small pads and a firm headband push larger ears toward the second camp. Pad swaps are the standard fix — with a caveat: owners warn that thick aftermarket pads overstress the headband and hinges, which are already the M40x's weak point.

One clear flaw sits next to a real disagreement. The flaw is the hinge: because the cups don't rotate as freely as the M50x's, the joint where the headband meets the cup is a known break point, and first-hand breakage reports recur across sources — the pleather also flakes after a couple of years. The detachable cable is welcomed as a genuine longevity win (though the connector is proprietary and replacements cost). Past that, one camp calls the M-series tank-like and drop-proof; the other notes the plastic is plainly cheaper than the M50x's.

The clearest weakness, and unusually poor for a sealed monitor — it does little against low-frequency noise and leaks enough that people near you hear it. That matters twice over for its intended job: it's a liability for tracking, where bleed lands in the take, and it's a poor commuter.

“This headset hardly quiets low-frequency sounds like a plane engine or the droning din of a train car.”

SoundGuys (Lil Katz)

“The ATH-M40x don’t have the best isolation, and at levels above 90 dB you’ll begin to experience significant amounts of bleed.”

Higher Hz (Brandon Schock)

Still widely regarded as a strong hundred-dollar buy — the owner ratings are high and large, and its defenders point out it has been recommended for a decade on merit. The dissent is comparative rather than absolute: at the same money the AKG K361/K371 is the challenger reviewers keep naming, and Sonarworks points elsewhere too. Worth noting the counter-argument that the K371's advantage is partly hype, and that it carries durability complaints of its own.