How We Research
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-27 · 7 min read · Independent comparison
• Audio-Technica ATH-M40x — biggest strength: a flat, accurate 40mm dynamic driver tuned across 15 Hz to 24 kHz, with two detachable cables and 90° swiveling earcups for one-ear monitoring. Biggest trade-off: it's a full-size over-ear headphone, so it's bulkier than an in-ear and relies on passive sound isolation rather than a sealed in-ear structure.
• Sony IER-M500 — biggest strength: a sealed, customizable in-ear fit with fitting supporters, four ear tip sizes and coreless ear hangers, giving strong noise isolation and a stable fit during movement. Biggest trade-off: it's an in-ear design, so you get that sealed fit rather than the open, over-ear feel of a studio headphone — and the fit is only as good as the tip you settle on.
• Pick the ATH-M40x if you sit at a desk, interface or mixer and want one headphone for mixing, monitoring and daily listening.
• Pick the IER-M500 if you perform live, move around while you monitor, or need to hear yourself clearly in a noisy room.
• Both are wired with a 3.5 mm jack and both are aimed at adult users doing serious audio work — the split is over-ear versus in-ear, not sound quality versus sound quality.
The ATH-M40x is the classic studio workhorse shape: an over-ear, closed-back monitor with 40mm dynamic drivers using rare earth neodymium magnets and copper-clad aluminum wire voice coils. Audio-Technica rates the frequency response from 15 Hz to 24 kHz, and the intent is a flat, accurate curve rather than a pumped-up consumer sound. In my opinion, that's exactly what you want when you're mixing or tracking and need to hear what's actually in the file instead of what a bass-boosted tuning wants you to hear.
Where it earns its keep is long sessions and flexible setups. The headband and earpads use pro-grade cushioning, and the frame folds down for transport. The 90° swiveling earcups are the detail I'd point at first for DJs and producers: flip one cup off your ear and you can cue a track while still hearing the room. On the connectivity side you get two detachable, single-sided cables — a coiled 3.9 to 9.8-foot cable for studio work and a straight 9.8-foot cable for desktop or mobile use — both with gold-plated 3.5mm plugs and a 1/4" screw-on adapter. That covers audio interfaces, mixers, headphone amps and phones without hunting for an adapter.
So who should buy it? Anyone whose monitoring happens in one place: a home studio, a desk with an interface, a DJ booth, or a practice room. It's also a sensible pick if you want one headphone that does critical listening and everyday listening without switching gear, and the bundle adds a stand, a case, a microfiber cloth and a headphone cleaner, which suits a fixed setup.
Who should skip it? If your monitoring happens on a stage, in a loud rehearsal space, or while you're moving around, an over-ear headphone is the wrong tool — it's heavier, it sits on top of your ears rather than sealing inside them, and it won't give you the locked-in isolation an in-ear can. If you also want maximum portability in a pocket-sized form, look elsewhere.
The IER-M500 is Sony's take on a stage-ready in-ear monitor, and the whole design is built around one idea: staying put and shutting out noise. The proprietary fitting system pairs an ergonomic shell with isolation earpieces, and Sony includes multiple fitting supporters plus noise isolation earbud tips in XS, S, M and L so you can dial in a personalized seal. The coreless ear hangers contour naturally to your ear, which is the part that keeps the monitors from tugging loose when you turn your head or move across a stage.
On sound, Sony frames the IER-M500 around accurate, balanced reproduction for live monitoring, with a large acoustic chamber and optimized internal structure delivering deep, controlled bass and refined high-frequency detail. It's also listed as Hi-Res Audio capable, with an extended frequency response for detailed reproduction of high-resolution sources. The sealed structure is the functional centerpiece: it reduces external noise so you can track your own performance clearly even when the room is loud — which is precisely the situation an in-ear monitor exists for.
Who should buy it? Live performers first — singers, instrumentalists, worship bands, anyone who needs to hear a mix over stage volume. Also a good fit if you rehearse in a loud room, or if you simply prefer the feel of a sealed in-ear to an over-ear headphone and want a wired connection you never have to charge. The included clothing clip, protective case and range of tip sizes point at a kit you're meant to carry and use repeatedly.
Who should skip it? If you do critical mixing at a desk and want a neutral reference you can wear for hours without anything sitting inside your ear canal, the over-ear ATH-M40x is the more natural fit. And if you've never gotten along with in-ears — or you don't want to spend time finding the right tip size, since the seal depends on it — this isn't the design to force yourself into.
• Best for studio mixing and critical listening → Audio-Technica ATH-M40x. Flat 15 Hz–24 kHz tuning and an over-ear, closed-back presentation made for reference work.
• Best for live performance monitoring → Sony IER-M500. Sealed in-ear structure, isolation tips and ear hangers built to survive stage volume and movement.
• Best for one-ear cueing → Audio-Technica ATH-M40x. The 90° swiveling earcups let you flip a cup off your ear without taking the headphones off.
• Best for maximum noise isolation → Sony IER-M500. A sealed in-ear design with multiple tip sizes isolates more effectively than an over-ear relying on passive isolation.
• Best for cable flexibility out of the box → Audio-Technica ATH-M40x. Two detachable cables (coiled 3.9–9.8 ft and straight 9.8 ft) plus a 1/4" adapter and gold-plated 3.5mm plugs.
• Best for long-session comfort if you dislike in-ears → Audio-Technica ATH-M40x. Cushioned headband and earpads with a foldable frame for storage.
• Best for a personalized, stable fit → Sony IER-M500. Four tip sizes, fitting supporters and coreless ear hangers that contour to your ear.
• Best for travel and storage → Both work, differently. The ATH-M40x folds into an included pouch; the IER-M500 comes with a protective case and clothing clip.
If I had to buy one, I'd buy the Audio-Technica ATH-M40x. My reasoning is simple: it's the more versatile monitor for the way most people actually work — a desk, an interface, a mixer, a DJ setup — and the flat 15 Hz–24 kHz tuning, swiveling earcups and two included cables cover more ground without asking you to fuss over tip sizes. I'd only switch to the Sony IER-M500 if my monitoring genuinely happens on a loud stage or while moving, because that's where its sealed, customizable in-ear fit and strong isolation win outright. Different jobs, different tools — pick the one that matches where you actually listen. And check the current price on Amazon before deciding, since both are wired monitors with very different kit contents.
how to check headphones battery
Neither the ATH-M40x nor the IER-M500 has a battery to check — both are wired headphones with a 3.5 mm jack, so they draw no power of their own. There's no charge level, no indicator and nothing to keep topped up. If you're used to wireless gear, this is one headache you simply don't have here.
how to check headphones
Start with the connection: both use a 3.5 mm jack, and the ATH-M40x also includes a 1/4" screw-on adapter for interfaces and mixers. Then check fit — on the IER-M500, try the XS, S, M and L tips and the fitting supporters to get a proper seal, since isolation depends on it. On the ATH-M40x, confirm the detachable cable is fully seated on the single-sided connector.
how to check headphones mic
Neither the ATH-M40x nor the IER-M500 is listed with a built-in microphone, so there's nothing to test on that front. Both are monitoring tools designed for listening, not for calls or recording your voice. If you need a mic, you'll pair these with a separate microphone rather than relying on the headphones.
how to check headphones battery on iphone
You can't, because there's no battery in either model — both are wired, so an iPhone won't show a headphone battery level for them. Plugging in via the 3.5 mm jack (with the appropriate adapter on newer iPhones) is the whole setup. No pairing, no charging, no battery widget to watch.
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