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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-17 · 8 min read · Independent comparison
These two look similar on paper — both are wired in-ear monitors with a 20Hz–40kHz frequency range — but they solve completely different problems. The ST2 is a digital-first earphone built around an ESS DAC chip and a USB-C connection. The Phantom is an analog-first earphone built around a balanced armature driver, a metal cavity, and a tuning switch. Once you understand that split, the choice gets easy.
• Hidizs ST2 — biggest strength: A USB-C plug with a built-in ESS ES9218AC Pro DAC, so it decodes high-resolution audio directly from your phone, tablet, PC or Mac without a dongle or external DAC.
• Hidizs ST2 — biggest trade-off: It is USB-C only. There is no 3.5mm option, so older analog gear, most dedicated DAPs with only a headphone jack, and consoles with a 3.5mm output are off the table.
• KZ Phantom — biggest strength: A tuning switch that combines into up to 12 different timbres, plus 37dB of passive isolation from a deep in-ear seal and a sturdy all-metal cavity.
• KZ Phantom — biggest trade-off: It is an analog 3.5mm earphone. Your sound quality depends entirely on whatever DAC or dongle you plug it into — nothing is built in.
• Choose Hidizs ST2 if you listen from a USB-C phone, laptop or tablet and want lossless playback, a mic, and in-line volume control without adding a dongle.
• Choose KZ Phantom if you game, monitor on stage, or want to shape your own sound signature with a tuning switch and a metal shell that shrugs off daily abuse.
The ST2 is, in my opinion, the more technically ambitious of the two. Hidizs has essentially taken a small desktop DAC and glued it to a pair of earphones. The ESS ES9218AC Pro chip handles 32-bit/384kHz PCM plus DSD128 and 8X MQA unfolding, which means it can decode high-resolution streams from services like TIDAL without any extra hardware. You plug it into a USB-C port and it just works — Windows, macOS, iOS, Android, HarmonyOS.
The driver setup is a pair of 10mm dynamic drivers with titanium coating, a PU+PEEK composite diaphragm, and a dual magnetic circuit. In plain terms, that design is aimed at efficiency and detail: the dual magnet raises high-frequency extension and cuts distortion, while the composite diaphragm keeps the midrange even. Hidizs quotes 32Ω impedance, 118dB sensitivity, 122dB dynamic range and 0.0012% THD. That low impedance and high sensitivity combination means it is easy to drive from a phone — no amp required.
Where it really earns its place is latency and battery. Because there is no Bluetooth and no internal battery, there is no pairing, no charging, and effectively no wireless delay. For gaming that matters — the ST2 is pitched at pinpointing footsteps and reloads in shooters. For long sessions, it simply never runs out, because it never had a battery to begin with. The HD mic converts voice to 24-bit/48kHz, so calls and voice chat come through clearly, and there is in-line volume control on a braided OFC cable.
Who should buy it: Anyone who listens from a USB-C device, wants true lossless playback without a dongle, and values zero charging and zero latency. It also suits gamers on PC or phone who want one cable for both audio and mic.
Who should skip it: If your main source is a 3.5mm jack — an older player, a console controller, a mixing desk — the ST2 is the wrong tool. It also gives you no tuning options; you get the Hidizs house sound and that is it.
The Phantom takes the opposite philosophy. It is an analog IEM with a 3.5mm jack, and its headline feature is control. A dedicated tuning switch lets you combine modes into up to 12 different timbres, which is unusual at this level — most earphones at any price give you one fixed sound. If you want a warmer, bass-forward presentation for gaming and a cleaner, flatter response for monitoring, the switch is what makes that possible without buying a second pair.
The driver is a balanced armature rather than a dynamic driver. Balanced armatures are typically prized for speed and separation, which lines up with KZ's pitch: hearing footsteps and pinpointing flanking enemies in a firefight, and pulling a clean monitor mix on stage or in a studio. Impedance is 41Ω with 128dB sensitivity, so it is still easy to drive from a phone or a cheap dongle, though it benefits from a decent source.
Build is a genuine strength here. The all-metal cavity is light but sturdy, and KZ says it reduces resonant interference — a metal shell tends to sound less hollow and survive more abuse than plastic. The ear-hook design spreads weight so you can wear it for hours with less fatigue, and the specs note 37dB of passive isolation from the deep seal. That is a big number, and it means you hear your mix — or your game — consistently regardless of how noisy the room is. KZ also states every part is serviceable, so it is not a disposable product.
Who should buy it: Gamers who want spatial accuracy and isolation, musicians and audio engineers who need a clean monitor mix, and anyone who likes to tune their sound rather than accept a fixed signature.
Who should skip it: If you want plug-and-play lossless decoding straight from a USB-C phone with no dongle, the Phantom cannot do that. There is no built-in DAC and no USB-C option — you will need a source with a 3.5mm output or an adapter.
• Best for lossless USB-C audio without a dongle → Hidizs ST2. The built-in ESS DAC does the decoding; the Phantom needs an external one.
• Best for sound customization → KZ Phantom. Up to 12 timbres via the tuning switch versus one fixed signature on the ST2.
• Best for gaming latency → Hidizs ST2. A wired USB-C digital path with no Bluetooth and no battery means effectively zero delay.
• Best for noise isolation → KZ Phantom. 37dB of measured passive isolation from the deep seal beats the ST2's sound-isolation approach.
• Best for build durability → KZ Phantom. An all-metal cavity with serviceable parts is built for years of daily use.
• Best for calls and voice chat → Hidizs ST2. The HD mic captures at 24-bit/48kHz, and there is in-line volume control on the cable.
• Best for monitoring and stage use → KZ Phantom. The balanced armature's separation and the flat-leaning tuning mode suit studio and live work.
• Best for never charging anything → Hidizs ST2. No battery at all means unlimited playback — though the Phantom also has no battery, it still needs a powered source.
If I were buying one of these for myself, I would pick the Hidizs ST2. The reason is simple: it removes the weakest link in most people's chain. I listen from a USB-C phone and a laptop, and having the DAC inside the cable means no dongle, no charging, and no Bluetooth compression — the ST2 measures up on paper with genuinely high-resolution decoding, and the 32Ω/118dB spec means it works from anything. In my opinion the ST2 is the better daily driver for a modern USB-C listener.
That said, the KZ Phantom is the smarter pick if your world is 3.5mm and you want to shape your own sound. The tuning switch, the metal shell, and that 37dB isolation figure make it the more versatile tool for gaming, stage and studio. Neither is objectively better — they are aimed at two different setups, and you should match the earphone to the jack you actually own.
Both are wired, so both avoid Bluetooth lag. The ST2 leans on a digital USB-C path with no battery for effectively zero latency, while the Phantom leans on a balanced armature's separation plus 37dB isolation to hear footsteps clearly. If you game on a phone or PC with USB-C, the ST2 is the cleaner fit. On a console or a 3.5mm setup, the Phantom is the one that works.
Not strictly. At 41Ω and 128dB sensitivity it is easy to drive from a phone or a basic dongle. But because there is no built-in DAC, the quality you get depends on your source, so a decent dongle will get more out of it than a weak headphone jack.
No. The ST2 is USB-C only. It ships with a USB-C to USB-A adapter, so it works with computers and USB-C phones, but there is no 3.5mm option. If your gear only has a headphone jack, choose the Phantom instead.
Ignore the sticker and look at what you already own. If you have a USB-C phone and want lossless audio with no extra gear, the ST2 saves you buying a dongle. If you have a 3.5mm source and want tuning options plus metal build, the Phantom gives you more flexibility per earphone. Check the current price on Amazon for both before you commit, since that is the only number that should tip a close call.
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