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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-25 · 6 min read · Independent comparison
• KZ Zax — biggest strength: A 16-driver hybrid array (per pair) with a 10 Hz–40 kHz range, 24 ohm impedance and 113 dB sensitivity, plus sound isolation rated to block up to 36 dB.
• KZ Zax — biggest trade-off: It ships as a single-cable package with no inline mic, so calls and on-the-fly cable swaps aren't part of the deal.
• BASN Metalen 4 — biggest strength: A 2BA+2DD hybrid per earbud with two detachable MMCX cables (one with an inline volume mic), a full accessory kit and a 1-year warranty.
• BASN Metalen 4 — biggest trade-off: Its frequency range tops out at 25 kHz with a narrower 16 Hz–25 kHz spread, so it trades some upper-end extension for punch.
• Who each is for: KZ Zax for listeners who want a wide, detailed wired monitor for long sessions; BASN Metalen 4 for musicians, singers and drummers who need cable flexibility and a complete kit.
The KZ Zax is built around a hybrid driver concept that KZ splits across four bands — low, mid, high and ultra-high — with a total of 16 sounding units across both sides. In plain terms, that means different drivers are handling different slices of the music instead of one driver doing everything. The spec sheet backs up the ambition: a 10 Hz–40 kHz frequency range, 24 ohm impedance, 113 dB sensitivity, and a 10mm dynamic driver with a PEK spring diaphragm for the low end. If you like hearing layers pulled apart — strings sitting behind a vocal, a bassline that stays distinct from the kick — that's the design goal here.
The physical design is just as deliberate. The faceplate is zinc alloy while the cavity is a transparent material, so you can see the internals, and KZ notes the metal finish resists oxidation over time. The fit is an over-the-ear, angled-insertion design (roughly a 45° in-ear angle with the cable routed behind the ear), which is the standard way to keep a monitor locked in place and cut cable noise. KZ rates the isolation at up to 36 dB, which is a meaningful number — that's the kind of seal that makes a commute or a noisy open office feel noticeably quieter. Weight is listed at 27 g, so it stays light for long listening.
Buy it if you want a wired, detail-forward monitor for music listening, streaming or long desk sessions, and you value isolation and a metal build. Skip it if you need a microphone for calls, want a spare cable in the box, or prefer a warmer, bass-first tuning — this one is aimed at clarity and a wide sound field, and it's the no-mic variant.
The BASN Metalen 4 takes a similar hybrid idea but tunes it for the stage. Each earbud packs 2 balanced armature drivers and 2 dynamic drivers — four per side — and BASN explicitly frames this around "enhanced bass response" with balanced, true frequencies. The numbers tell a slightly different story than the KZ: 16 ohm impedance (easy to drive), 108 dB sensitivity, and a 16 Hz–25 kHz range. You give up some upper-frequency extension, but you gain low-end authority and an easy load for phones, small interfaces and stage packs.
Where BASN really separates itself is the kit. You get two detachable MMCX cables — an upgraded OFC silver-plated cable and a fiber cable with an inline volume mic — so you can swap between critical listening and taking a call without buying anything extra. The box also includes S/M/L tips plus memory foams, a T-shirt clip, velcro strips, a cleaning brush, a 1/4" adaptor and a carrying case. The shell uses CNC machining and electroplating on the cover, which BASN says improves corrosion resistance and resists surface wear. The rounded-tip shape and metal enclosure point to a fit that's meant to be jammed in and forgotten during a set.
Buy it if you're a musician, singer, drummer or bassist who needs cable options, a mic for quick communication, and a bass-forward monitor that's easy to drive. Skip it if you mainly want the widest possible treble extension or you prefer a single, no-fuss cable — the accessory load and two-cable setup are the whole point here.
• Best for detail and soundstage → KZ Zax. The 16-driver hybrid with a 10 Hz–40 kHz range is aimed squarely at resolution and a wide field.
• Best for bass-forward stage use → BASN Metalen 4. Its 2BA+2DD design is tuned around enhanced low-end, and 16 ohm impedance makes it easy to drive.
• Best for noise blocking → KZ Zax. Its isolation is rated up to 36 dB, a strong figure for shutting out the world.
• Best for cable flexibility → BASN Metalen 4. Two detachable MMCX cables, one with an inline volume mic, beats a single fixed setup.
• Best for calls and quick communication → BASN Metalen 4. The mic cable and call/voice/music controls make it the practical pick.
• Best accessory package → BASN Metalen 4. Tips, foams, clip, brush, adaptor, case and a 1-year warranty are all included.
• Best for long, fatigue-free listening → KZ Zax. Lightweight at 27 g with an ergonomic over-ear design built for extended sessions.
• Best for durability on the move → BASN Metalen 4. CNC metal covers with electroplating are built to resist wear and corrosion.
In my opinion, the safer buy for most people is the BASN Metalen 4. It's easier to drive, comes with two cables including one with a mic, and the accessory kit plus 1-year warranty covers more real-world situations — commuting, calls, rehearsals, tracking. The KZ Zax is the better pick if you specifically want a wide, detail-heavy wired monitor with strong isolation and don't need a mic or spare cable. If you're torn, ask yourself one question: do you need to talk and swap cables, or do you just want to disappear into the music? Answer that and the choice is obvious.
how to fit in ear headphones
Insert the nozzle at an angle into your ear canal and then rotate it toward the back of your head — KZ describes its intended fit as roughly a 45° insertion with a 270° rotation and the cable routed behind the ear. A proper seal is what delivers both comfort and isolation, so experiment with the included tip sizes until it feels snug without pressure.
how to clean in ear headphones
Wipe the nozzle and shell with a dry cloth and clear any earwax from the tip, using the small cleaning brush that BASN includes in its kit. Detachable cables help here — on both the KZ Zax (2-pin) and the BASN Metalen 4 (MMCX), you can unplug the cable before cleaning so you don't stress the connector.
how to open in ear headphones
Neither model is meant to be opened by the user — the KZ Zax's transparent cavity lets you see the drivers but isn't designed for disassembly, and the BASN Metalen 4's CNC metal shell is sealed. If a driver stops working, use the warranty (1 year on the BASN, 1 year listed on the KZ) rather than prying the shell apart.
how to ear headphones
If you mean wearing them, both are in-ear monitors that sit inside the canal with the cable looped over the top of your ear — that over-ear routing is what keeps them stable during movement. Match the tip to your ear size, push in gently to seal, then drape the cable behind your ear and down your back.
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