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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 wired, high-fidelity in-ear monitor with a metal-and-resin build for focused listening, gaming and everyday music, choose Kinboofi KZ ZS10; if you need a fully waterproof, Bluetooth-and-MP3 hybrid built specifically for swimming and sweaty training, choose BeatH2O S36.
• Kinboofi KZ ZS10 — biggest strength: a five-driver hybrid setup (4 balanced armatures + 1 dynamic driver) with a PCB frequency-dividing board, a 304 stainless steel faceplate over an acrylic resin body, and a detachable 0.75mm 2-pin 6N OFC cable.
• Kinboofi KZ ZS10 — biggest trade-off: it is wired only, with no microphone on this version, no waterproof rating, and touch controls on the housings that some listeners find fussy.
• BeatH2O S36 — biggest strength: IPX8 waterproofing submersible to 6 m, 8GB of built-in memory for offline MP3 playback, and up to 10 hours of Bluetooth or 8 hours of MP3 mode.
• BeatH2O S36 — biggest trade-off: Bluetooth simply cannot transmit underwater, so swimming means MP3 mode only, and the ABS build is tuned for water sports rather than critical listening.
• Who each pick is for: the KZ ZS10 suits desk, commute and gaming listeners who want wired detail; the S36 suits swimmers and heavy-sweat athletes who need music in the water.
The KZ ZS10 Pro is, in my opinion, a listening-first in-ear monitor. The headline is the driver array: four balanced armatures plus one 10 mm dynamic driver, split by a PCB frequency-dividing board that assigns the highs, mids and lows to the units best suited for them. That is the kind of architecture you normally associate with stage monitors, and it is why the ZS10 Pro reads as a detail-forward earphone rather than a bass-first consumer bud. The claimed frequency response reaches up to 40,000 Hz with 30 ohm impedance, which makes it easy enough to drive from a phone or a small dongle DAC without extra amplification.
Build quality is the second reason to consider it. The housing combines an acrylic resin body with a 304 stainless steel faceplate, which is a meaningful step up in rigidity from all-plastic IEMs and gives it a heavier, more premium feel in the hand. The detachable 0.75mm 2-pin cable matters more than it sounds: if a cable fails, you replace the cable instead of the earphone. The included 6N OFC cable is a copper design chosen for clean signal transfer, and the package ships with three pairs of silicone tips and a manual.
Fit is where the ZS10 Pro earns its keep for long sessions. The cavity is molded around ear-canal data to sit like a custom piece, and KZ rates the passive isolation at 26dB of noise reduction. That is enough to dull a bus engine, a keyboard clatter or an office hum without any active electronics. It is a wired 3.5 mm design with touch controls on the housing and a rounded tip shape, and this specific version has no microphone, so it is not the one to buy if you take a lot of calls.
Who should buy it: gamers who want positional detail, commuters who prefer a cable and no charging, and anyone who wants a genuinely multi-driver IEM at an entry-level price point. Who should skip it: swimmers, gym-goers who sweat heavily, and anyone who wants wireless freedom or a built-in mic. There is no water-resistance rating here, so treat it as an indoor and dry-outdoor earphone.
The BeatH2O S36 is a different animal entirely. It exists to solve one problem: music while your head is underwater. The IPX8 rating and 6 m (about 20 ft) submersibility are the core of the design, and the brand is refreshingly blunt about the physics — Bluetooth signals do not travel through water, so swimming playback happens in MP3 mode from the built-in 8GB of memory. That memory holds over 1,500 songs, and you load it by copying files from a computer after converting them to MP3, WMA, APE or FLAC. No phone required, no signal required.
The fit system is clearly built by people who have lost earbuds in a pool. The ear hooks are stretchable and rotate through 30 degrees, and the package includes two full sets of eartips in S, M and L — dual-layer waterproof tips for swimming and single-layer tips for everyday use. The brand also recommends wearing a swim cap over the headphones during intense laps or flip turns to lock them down, which tells you they understand how easily in-ears pop out mid-stroke. The 12mm dynamic drivers are tuned for underwater acoustics and balanced output rather than heavy bass, a deliberate choice since a thick low end is hard to perceive underwater anyway. The housing is ABS, the cable is soft, and the whole thing weighs about an ounce.
Battery and controls round out the picture. A two-hour USB magnetic charge gets you up to 10 hours in Bluetooth mode or 8 hours of continuous MP3 playback. Buttons handle volume, track skipping and playback order with short, long and double presses, and Bluetooth 5.4 covers the out-of-water listening. Note that playback order can reset after a full power-off — a deliberate power-saving behavior, not a fault.
Who should buy it: lap swimmers, triathletes, open-water swimmers and anyone whose workouts drown normal earbuds in sweat. Who should skip it: listeners who want a single pair for critical music listening, since the ABS build and underwater tuning are purpose-built rather than all-round. If you mostly listen at a desk, the S36 is the wrong tool.
• Best for swimming → BeatH2O S36. IPX8 and 6 m submersibility with MP3-mode playback is the whole point of this earphone.
• Best for wired fidelity and detail → Kinboofi KZ ZS10. Five drivers and a PCB frequency-dividing board deliver a more layered sound than a single-driver sports bud.
• Best for battery life and cordless freedom → BeatH2O S36. Up to 10 hours on Bluetooth and 8 hours in MP3 mode, with Bluetooth 5.4.
• Best for durability of the housing → Kinboofi KZ ZS10. Stainless steel faceplate plus acrylic resin, with a replaceable 0.75mm 2-pin cable.
• Best for noise isolation without electronics → Kinboofi KZ ZS10. Passive isolation rated at 26dB, versus the S36's focus on water safety and seal.
• Best for offline music with no phone → BeatH2O S36. 8GB of built-in storage holds over 1,500 songs.
• Best for calls → neither, honestly. The KZ ZS10 version here has no microphone, and the S36's Bluetooth mode works out of water but is not a dedicated headset.
• Best for gaming and positional audio → Kinboofi KZ ZS10. The multi-driver tuning is the better fit for footsteps and directional cues.
If I had to pick one, I would buy the Kinboofi KZ ZS10 — but only because my listening happens at a desk, not in a pool. In my opinion, the five-driver array, the 26dB passive isolation, the steel-and-resin shell and the swappable 2-pin cable give you far more earphone for general music, gaming and commuting, and the wired connection means zero charging anxiety. The BeatH2O S36 is the better product for exactly one job, and it does that job extremely well; if swimming is your use case, buy the S36 and don't look back. Buy the KZ ZS10 for sound, the S36 for water. Check the current price on Amazon before you commit, since both sit in very different budget brackets.
how to clean in ear earbuds
For the KZ ZS10, wipe the resin-and-steel housing with a dry cloth and gently clear the nozzle of earwax — you can pull the silicone tips off and rinse those separately since the cable is detachable. The S36 needs more care: its IPX8 seal is rated for water, so rinse the eartips after pool use and let everything air-dry before charging, since the magnetic charging contacts should stay clean and dry.
how to put in ear earbuds
With the KZ ZS10, pull the top of your ear up and back, then seat the rounded tip so the housing sits flush in the canal — the molded cavity is designed to lock in on its own. With the S36, hook the top of your ear over the upper ear hook first, rotate the hook to 30 degrees to find your angle, then press the eartip into place; many swimmers add a cap over the top for extra security.
how to fit in ear earbuds
Fit comes down to tip size. The KZ ZS10 ships with three pairs of silicone tips, so cycle through them until you get both a seal and no pressure after ten minutes. The S36 includes six pairs total — S, M and L in both dual-layer waterproof and single-layer daily versions — and the ear hooks also stretch and rotate, so you can tune both the tip and the hook angle to your ear.
how to ear earbuds
If you mean which one to use when, the rule is simple: dry listening, wired detail and isolation point to the Kinboofi KZ ZS10; anything wet, sweaty or underwater points to the BeatH2O S36, which needs MP3 mode once Bluetooth can't reach you. Match the earphone to the environment rather than trying to force one pair to do both.
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See also: Kinboofi KZ ZS10 vs Sennheiser Consumer Audio CX: In Ear, MIDOLA Volume Limited 85/110dB vs MAcnas Earbuds Open Ear, Boytond Open Ear Earbuds vs ZYHKON Sleep Earbuds