We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-30 · 7 min read · Independent comparison
If you want a wired in-ear monitor that blocks outside noise through a deep, ergonomic seal and gives you upgradeable, musician-grade sound, choose erjigo KZ ZST X; if you need an over-ear gaming headset with a boom mic, big 50mm drivers and a sturdy aluminum frame for long sessions at your desk, choose IYGR K98.
• erjigo KZ ZST X — biggest strength: a hybrid 1DD+1BA driver setup in a molded in-ear shell, so it seals your ear canal and physically blocks chatter, traffic and keyboard clatter while delivering a wide 20Hz–40kHz range.
• erjigo KZ ZST X — biggest trade-off: it's a wired 3.5mm in-ear, so there's no boom mic arm and no over-ear cushioning — fit depends entirely on getting the silicone tips seated properly.
• IYGR K98 — biggest strength: an over-ear design with 50mm neodymium dynamic drivers, memory foam cushions and an aluminum alloy frame, plus a noise-isolating microphone for voice chat.
• IYGR K98 — biggest trade-off: it's a bulkier wired headset (8 ounces) aimed at desk and console use, and its frequency response tops out at 20kHz with 32Ω impedance, so it needs a bit more drive than a low-impedance IEM.
• Pick erjigo KZ ZST X if you want maximum isolation in the smallest possible package — commuting, practising, gaming on the move.
• Pick IYGR K98 if you want one headset that does game audio and voice chat on PC, PS5, PS4, Xbox or Switch.
The KZ ZST X is a hybrid in-ear monitor: one 10mm dual-magnetic dynamic driver for the low end, paired with a 30095 balanced armature for the highs. The numbers tell you what that combination is chasing — a 20Hz–40kHz frequency range, 107dB sensitivity and just 12Ω impedance. Low impedance plus high sensitivity means it's easy to drive straight from a phone or laptop jack without a dedicated amp. In my opinion, that's the single most practical thing about it for everyday listeners.
The isolation story here is mechanical, not electronic. There's no active noise cancellation chip — instead, the shell is molded around the shape of the human auricle, and the soft silicone tips sit inside your ear canal. That physical seal is what reduces external noise, and it's the reason IEMs like this are popular with musicians for stage monitoring. The ear-hook design keeps them anchored during running, workouts or long sessions, and the whole thing weighs about 3g per earbud.
The detachable 0.75mm 2-pin cable is a real long-term plus. It's a 100-core silver-plated copper wire with added Kevlar fiber, and because it unplugs, you can replace it or swap it later instead of retiring the earphones. You get a 1.25m tangle-resistant cable terminating in a universal 3.5mm plug that works with phones, laptops, tablets, MP3 players and consoles.
Who should buy it: commuters, gym-goers, gamers who want in-ear isolation, and anyone who wants a wired monitor they can maintain. Who should skip it: if you want an over-ear headset with a built-in boom mic for team chat, or you dislike things sitting inside your ear canal, this isn't the shape for you. Note the mic is listed as optional, so check the variant you're buying.
The IYGR K98 is the opposite philosophy: a full over-ear gaming headset. It uses 50mm neodymium dynamic drivers with 32Ω impedance, 105dB sensitivity and a 20kHz frequency ceiling, and it lists 15ms audio latency. Stereo surround sound is the pitch, and the oval ear cups are padded with memory foam — that's the part that matters over a three-hour session, because pressure on the ears is what usually ends a gaming night early.
Build-wise it leans rugged rather than light. The frame is aluminum alloy, the enclosure is ABS plastic, and the whole headset weighs 8 ounces. It ships with a user manual and carries a 2-year warranty. Controls are simple: a push-button volume control on the cable, and sound isolation rather than active noise cancellation. The noise-isolating microphone is the point of the headset — it's built for voice chat, and it's tuned to reject background noise so your teammates hear you rather than your room.
The isolation approach is again passive: closed oval cups plus memory foam cushions. That blocks some ambient sound, but it won't seal as tightly as an in-ear with silicone tips jammed into your canal. That's the honest trade-off of over-ear comfort.
Who should buy it: PC, PS5, PS4, Xbox and Switch players who want one wired headset for game audio and comms, and who prefer cups over in-ears. Who should skip it: anyone who wants something pocketable for a commute, or who needs the widest possible frequency range for critical music listening. The 20kHz ceiling and 32Ω impedance make it a gaming-first pick, not an audiophile one.
Side-by-Side: Which Should You Choose?
• Best for noise isolation → erjigo KZ ZST X. In-ear silicone tips seal the ear canal directly, which blocks more ambient noise than over-ear cushions can.
• Best for gaming voice chat → IYGR K98. It has a dedicated noise-isolating microphone; the KZ ZST X's mic is listed as optional.
• Best for commuting and workouts → erjigo KZ ZST X. Roughly 3g per earbud, an ear-hook that holds during running, and a 1.25m cable.
• Best for sound range → erjigo KZ ZST X. 20Hz–40kHz versus the K98's 20kHz ceiling, plus a hybrid DD+BA driver setup.
• Easiest to drive from a phone → erjigo KZ ZST X. 12Ω impedance and 107dB sensitivity versus 32Ω and 105dB.
• Best for repairability → erjigo KZ ZST X. The 0.75mm 2-pin detachable cable means a broken wire isn't the end of the earphones.
• Best for console plug-and-play → IYGR K98. It's explicitly listed for PC, PS5, PS4, Xbox and Switch with a 3.5mm jack.
If I had to pick one, I'd buy the erjigo KZ ZST X. The keyword here is "noise isolating," and a properly seated in-ear beats an over-ear cushion at that job every time — the silicone tip seals the canal itself instead of just covering it. Add the hybrid driver setup, the 20Hz–40kHz range and the 12Ω impedance that runs happily off a phone, and it covers commuting, gym and solo gaming in one tiny package. I'd only switch to the IYGR K98 if voice chat and long desk sessions were my main use, because that's where its boom mic and memory foam cushions earn their keep.
how to noise cancelling headphones work
There are two different mechanisms, and neither product here uses the active kind. Active noise cancellation uses microphones and circuitry to cancel incoming sound waves. Both the KZ ZST X and the IYGR K98 use passive sound isolation instead — the KZ ZST X seals your ear canal with silicone tips, while the K98 covers your ears with closed oval cups and memory foam cushions.
how to use noise cancelling headphones
With passive isolation, there's no button to press and no battery to charge. You simply put them on correctly: for the KZ ZST X, fit the silicone tip so it sits snugly inside your ear canal and let the ear hook hold it in place. For the IYGR K98, adjust the headband so the memory foam cushions sit flat around your ears without gaps. A good seal is what does the noise blocking.
Play something quiet at low volume in a noisy room and listen for how much of the background disappears. For the KZ ZST X, try each silicone tip and compare — isolation changes noticeably with fit. For the IYGR K98, check that the cushions fully surround your ears with no air gaps, since a poor seal on an over-ear headset is the usual reason isolation feels weak.
Are the erjigo KZ ZST X and IYGR K98 wired or wireless?
Both are wired and connect through a 3.5mm jack. The KZ ZST X uses a detachable 0.75mm 2-pin cable that's 1.25m long and works with phones, laptops, tablets, MP3 players and consoles. The IYGR K98 is a single wired headset listed for PC, PS5, PS4, Xbox and Switch, with an inline push-button volume control.
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