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If you want a wired in-ear monitor built to survive stage use and studio sessions — with two swappable cables in the box and a metal shell that shrugs off wear — choose BASN Metalen 4; if you need a light, ergonomic hybrid IEM tuned for long listening sessions and lag-free gaming, choose Kinboofi KZ ZA12.
• BASN Metalen 4 — biggest strength: four hybrid drivers per earbud (2 balanced armature + 2 dynamic) inside a CNC-machined, electroplated metal shell, plus a genuinely complete kit with two detachable MMCX cables.
• BASN Metalen 4 — biggest trade-off: a 16 ohm impedance and 108 dB sensitivity make it very easy to drive, but the lower impedance means it can hiss on poorly shielded sources, and the full kit makes it bulkier to carry than a bare earbud.
• Kinboofi KZ ZA12 — biggest strength: a hooked, ergonomic shell with passive noise cancellation and a 20 Hz–40 kHz frequency range, tuned for a transparent, natural sound and a light feel on the ear.
• Kinboofi KZ ZA12 — biggest trade-off: at 45 ohm impedance and 103 dB sensitivity it needs more power to reach the same loudness, and the base configuration ships without a microphone.
• Pick BASN Metalen 4 if you're a musician, drummer, bassist or singer who wants a rugged, do-everything kit.
• Pick Kinboofi KZ ZA12 if you're an audiophile or gamer who wants a light, comfortable hybrid IEM for long sessions.
The Metalen 4 is built around a four-driver hybrid layout: two balanced armature drivers and two dynamic drivers in each earbud. In practice that's a design meant to split the work — the armatures handle detail and definition, the dynamics carry the low end. BASN's own framing of the Metalen line leans on enhanced bass response and a balanced, "true" frequency spread, which lines up with the quoted 16 Hz–25 kHz range. For anyone who plays an instrument rather than just listens to one, that combination of reach-down bass and upper-detail retrieval is the whole point.
The physical build is where this one separates itself. The cover is CNC-machined and electroplated metal, which BASN says improves corrosion resistance and protects the surface from wear and tear. That matters if the earbuds live in a gig bag, get tossed between sets, or sit against a drum stool for years. You also get two detachable MMCX cables — one silver-plated OFC cable without a mic, and one fiber cable with an inline volume control and mic — so you can swap to a headset setup for calls or keep the signal path clean for monitoring. Inline volume control is a rare convenience at this tier and something I'd genuinely use.
The kit is the other half of the story. In the box: two earbuds, both cables, a T-shirt clip, small/medium/large tips plus memory foam tips, velcro strips, a cleaning brush, a 1/4-inch adapter and a carrying case — all backed by a 12-month warranty. That 1/4-inch adapter is the tell: this is aimed at people plugging into an amp, mixer or interface, not just a phone.
Buy it if you're a singer, drummer or bassist who needs one rugged set that covers stage monitoring, practice and calls. Skip it if you want the lightest possible earbud, or if you mostly game and want the smallest, most unobtrusive shell.
The ZA12 takes the opposite approach: comfort first. Its shell uses a hooked, ergonomic shape that the design notes describe as hugging the ear to minimize fatigue over long sessions, and the whole thing is deliberately lightweight — the listed item weight is 0.06 kg, and the copy repeatedly stresses "light to wear." If you've ever pulled IEMs out after two hours because your ear canals were sore, that's the problem this design is attacking. The faceplate is metal with a matte black finish and a fine-textured, classy look that doesn't scream "budget."
Sonically, this is a 2 dynamic + 4 balanced armature hybrid with a stated 20 Hz–40 kHz range — wider on paper at the top end than the BASN. Kinboofi describes the tuning as transparent and natural overall, with mellow vocals, rich detail, mild highs and an extensive sound field. The spec sheet confirms the hybrid driver type. Impedance is 45 ohm and sensitivity 103 dB, which is stiffer than the BASN — you'll want a decent dongle or source rather than a weak onboard jack.
Two practical notes stand out. First, the ZA12 uses passive noise cancellation, i.e. physical sealing rather than electronics, so tip fit does the isolating work; it ships with small, medium and large tips. Second, the cable is a detachable, 1.2-meter silver-plated twin cable using a 2-pin connector, which Kinboofi says reduces signal loss, resists oxidation and tangling, and — importantly — protects the pins from snapping off inside the housing. The version described here has no microphone, so it's a listening-only product.
Buy it if you're an audiophile or gamer who wants a light, comfortable hybrid with a wide frequency range and a lag-free wired connection — the copy specifically pitches zero-latency performance for competitive gaming. Skip it if you need to take calls, or if your source is a weak phone jack that struggles with 45 ohm loads.
• Best for stage and studio monitoring → BASN Metalen 4. The 1/4-inch adapter, T-shirt clip and dual MMCX cables are literal gig-bag tools.
• Best for long-session comfort → Kinboofi KZ ZA12. The hooked ergonomic shell and low weight are designed around fatigue reduction.
• Best for call and voice use → BASN Metalen 4. One of its two cables includes an inline mic and volume control; the ZA12 as listed has no microphone.
• Best for easy driving from a phone → BASN Metalen 4. At 16 ohm and 108 dB it needs far less power than the 45 ohm / 103 dB ZA12.
• Best for gaming → Kinboofi KZ ZA12. Wired, zero-latency by design, with a wide 20 Hz–40 kHz range.
• Best for durability in a bag → BASN Metalen 4. CNC metal cover with electroplating to resist corrosion and surface wear.
• Best for out-of-the-box extras → BASN Metalen 4. Two cables, three tip sizes plus memory foam, cleaning brush, clip, adapter and case.
• Best for a cleaner, more minimalist setup → Kinboofi KZ ZA12. One 1.2 m silver-plated detachable cable, matte black, nothing extra.
In my opinion, the BASN Metalen 4 is the better buy for most people, because the kit and the dual-cable design solve problems the ZA12 simply doesn't address — you get a mic cable, a clean cable, an amp adapter, memory foam tips and a case without buying anything else. The 16 ohm impedance also means it'll sound loud and full from almost any source. I'd only steer you to the Kinboofi KZ ZA12 if comfort over multi-hour sessions and gaming are your absolute priorities, and you don't need a microphone. Check the current price on Amazon before deciding.
how to fit in ear headphones
Push the tip into your ear canal and twist slightly until it seals — the seal is what makes bass and isolation work. The BASN Metalen 4 includes small, medium and large tips plus memory foam tips, while the KZ ZA12 ships with small, medium and large sizes; try each until the sound locks in and outside noise drops.
how to clean in ear headphones
Wipe the nozzles and shells with a dry cloth and clear wax from the mesh with a soft brush. The BASN Metalen 4 kit actually includes a cleaning brush, and its metal cover is electroplated for corrosion resistance, which helps against everyday sweat and grime. Remove the tips periodically and clean underneath them.
how to open in ear headphones
These are sealed, non-user-serviceable shells, so "opening" them means detaching the cable, not the housing. The BASN Metalen 4 uses MMCX detachable cables and the KZ ZA12 uses a detachable 2-pin cable — pull straight and gently at the connector, and never pry the earpiece itself apart.
how to ear headphones
If you mean how to wear them, the hook-shaped KZ ZA12 is designed to hug the ear so the cable routes over the top and down your back. The BASN Metalen 4 uses a rounded-tip shell worn straight into the canal; either way, loop the cable over your ear for stability and clip it with the included T-shirt clip on the BASN.
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