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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
If you want a hybrid six-driver in-ear monitor built for stage and studio monitoring with swappable 3.5mm and 4.4mm plugs, choose BASN BmasterX 6; if you need a flat, closed-back over-ear monitor with 90° swiveling earcups, detachable cables and a foldable frame, choose Audio-Technica ATH-M40x. These two sit at opposite ends of the monitor-headphone spectrum — one lives inside your ear, the other wraps around it — and that single design difference drives almost every other decision you'll make.
• BASN BmasterX 6 biggest strength: a hybrid six-driver array (1 dynamic + 3 balanced armatures + 2 piezoelectric tweeters) in a resin-and-aluminum shell with seven pairs of eartips — deep isolation and a full-range tuning aimed squarely at monitoring, mixing and stage work.
• BASN BmasterX 6 biggest trade-off: it's an in-ear, so it's wired-only with no battery or wireless mode, and the fit-sensitive deep-seal design isn't for people who dislike things sitting in their ear canal.
• Audio-Technica ATH-M40x biggest strength: 40mm dynamic drivers with neodymium magnets and copper-clad aluminum voice coils, delivering a flat response from 15 Hz to 24 kHz across a closed-back, over-ear frame that folds flat.
• Audio-Technica ATH-M40x biggest trade-off: it's also wired-only, and the over-ear design blocks less of the outside world than a properly sealed IEM — plus it's bulkier to carry than a pocket-size monitor.
• Pick BASN BmasterX 6 if you're a musician, singer, drummer or DJ who wants maximum isolation and an in-ear monitoring workflow.
• Pick Audio-Technica ATH-M40x if you're mixing, editing or critically listening at a desk and want over-ear comfort with one-ear monitoring.
The BmasterX 6 is a purpose-built in-ear monitor. BASN splits the work across six drivers per side: one dynamic driver handles warm low end, three balanced armatures carry the mids, and two piezoelectric tweeters take the top end. In practical terms, that's a design aimed at pulling detail out of a mix without smearing the low end — the kind of thing you notice when you're trying to hear a click track over a loud stage.
Isolation is the headline. BASN tunes these specifically for noise blocking, and the package gives you seven pairs of replacement eartips, which matters more than it sounds: an IEM only isolates as well as its seal, and having that many tip options means most people can find one that actually seals. The shell is resin with an aluminum plate, and the construction is deliberately lightweight so you can wear them for a full set without fatigue.
The cable setup is the detail that separates this from a casual pair of earbuds. You get a silver-plated OFC cable with interchangeable 3.5mm and 4.4mm plugs, so the same monitors work with a phone or laptop (3.5mm) and a balanced output on a DAP, audio interface or stage mixer (4.4mm). Impedance is 20 ohm and sensitivity is 107 dB, which makes them easy to drive from modest sources. Throw in the 1/4-inch adapter, cable clip, cleaning tool, protective case and a one-year warranty, and it's a complete gig kit rather than just a pair of earphones.
Buy it if: you perform, monitor on stage, DJ, or want a pocketable, high-isolation monitor with a balanced-capable cable. Skip it if: you want over-ear comfort, one-ear monitoring, or you simply don't like in-ear fit — no amount of tip-swapping fixes a preference.
The ATH-M40x is the classic studio-monitor shape: over-ear, closed-back, built around 40mm dynamic drivers with rare earth neodymium magnets and copper-clad aluminum wire voice coils. Audio-Technica rates the response at 15 Hz to 24 kHz and describes it as flat and accurate — that's the point of a monitor headphone. You're not buying it for a boosted, fun sound; you're buying it so what you hear translates when you move to another system.
The ergonomics are where this design quietly earns its keep. The 90° swiveling earcups let you flip one side off your ear for one-ear monitoring — the standard move for DJs cueing the next track and for engineers checking a room. Pro-grade cushioning on the headband and earpads is there for long sessions, and the closed-back cups provide sound isolation, though an over-ear seal is never as total as a properly fitted IEM.
Connectivity is generous in a different way than the BASN. 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 desk or mobile use, both with gold-plated 3.5mm plugs and a 1/4-inch screw-on adapter. The frame folds for storage, and this particular bundle adds a carrying case, a headphone stand, a microfiber cloth and a bottle of headphone cleaner — which is a genuinely practical set if you're setting up a workstation.
Buy it if: you mix, edit, produce, DJ or do long critical-listening sessions at a desk, and you want over-ear comfort plus one-ear monitoring. Skip it if: you need maximum isolation in a loud environment or you want something that disappears into a pocket.
• Best for stage and live monitoring → BASN BmasterX 6. Six drivers, resin-and-aluminum shells and seven tip sizes are built for performers who need isolation and durability.
• Best for mixing and critical listening → Audio-Technica ATH-M40x. A flat 15 Hz–24 kHz tuning from 40mm dynamic drivers is the more traditional reference-listening setup.
• Best for maximum noise blocking → BASN BmasterX 6. A sealed in-ear with the right tip will out-isolate a closed-back over-ear in a loud room.
• Best for one-ear monitoring → Audio-Technica ATH-M40x. The 90° swiveling earcups make this trivial; you can't do it with an IEM.
• Best for balanced audio gear → BASN BmasterX 6. The interchangeable 3.5mm/4.4mm plugs cover both single-ended and balanced outputs.
• Best for long desk sessions → Audio-Technica ATH-M40x. Over-ear cushioning on the headband and earpads is designed for extended wear without ear fatigue.
• Best for travel and storage → Audio-Technica ATH-M40x. The foldable frame plus carrying case and pouch make it easier to pack than loose IEMs and tips.
• Best for portability → BASN BmasterX 6. An 8.5-ounce kit that includes a compact case, adapter, cable clip and cleaning tool fits in a gig bag without a second thought.
In my opinion, this comes down to where you listen, not which one is "better." If your work happens on a stage, in a rehearsal room or anywhere loud, I'd buy the BASN BmasterX 6 — the hybrid driver setup, the seven tip sizes and the 3.5mm/4.4mm swappable cable are exactly what a monitoring IEM should offer. If your work happens at a desk and you want flat, over-ear reference sound with one-ear monitoring, I'd buy the Audio-Technica ATH-M40x. Pick the form factor first; everything else follows.
FAQ
Start with the basics: confirm the cable is fully seated, then verify the source. With the BmasterX 6, check that you're using the correct plug — 3.5mm for phones and laptops, 4.4mm for balanced outputs — and that the detachable cable is pushed in properly. With the ATH-M40x, try the second included cable and make sure the 1/4-inch adapter is screwed on tight if you're plugging into studio gear.
Neither the BASN BmasterX 6 nor the ATH-M40x lists a built-in microphone. The M40x does list a push-button control method, but the data sheets don't describe a mic on either product, so for calls or streaming you'd need a separate microphone. Don't buy either one expecting built-in voice pickup.
There's no battery to check because both are wired, so an iPhone won't show a battery indicator for them. To use the ATH-M40x with an iPhone you'd need the right adapter for its 3.5mm plug, and the BmasterX 6 works over its 3.5mm plug. Any battery readout you see on an iPhone belongs to a wireless device, not to either of these.
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