The KZ ZST are okay mixed usage wired in-ears. They have a passable sound quality but will be better suited for bass-heavy genres. They have a unique style and stand out from other earbuds. They have a similar look to the KZ AS10 and KZ ZS10 but feel slightly cheaper made, and their fit won’t be great for commuting. On the upside, they are still well-built and their cable is braided and detachable. You can also get a Bluetooth adapter to make them wireless. The model we tested didn’t have in-line controls or a microphone, but KZ does offer a variant with both.
The KZ ZST are straightforward wired in-ears that are fairly similar to other KZ headphones in design. They have a bulky build, but these are actually one of the smallest KZ headphones we’ve reviewed so far. They still have a similar transparent look but feel more plasticky than the other models. On the upside, their braided cable seems sturdy and is also detachable and replaceable. They are very lightweight headphones and barely put any pressure on your ear, but the in-ear fit might not be for everyone. The model we’ve tested doesn’t have an in-line remote, but there is a variant with one.
The KZ ZST are very similar in style to the other KZ headphones we’ve reviewed so far, but their overall build is smaller and feels a bit more plasticky than the rest. These headphones still look better than what their price tag suggests, thanks to their transparent casing that lets you see the electronic parts of the headphones. Their braided cable also adds to their premium feeling. They come in a few flashy and colorful designs, as well as a black and a carbon fiber designed one, to suit your preferred style.
The ZST are as comfortable as the other KZ models. They are very lightweight and their angled design fits nicely inside the ear without putting too much pressure. They are a bit bulkier than most in-ears, but their overall build is a bit smaller than other KZ headphones. On the upside, they also come with different tip options to help you find a better fit and air-tight seal.
These headphones do not have an in-line remote with controls. However, there is a model variant with a one-button control scheme on the in-line remote.
The KZ ZST headphones are very portable and will easily fit inside most pockets or in a bag. Their ear-hook design and the bulkier buds take up slightly more space than most in-ears, but you shouldn’t have any problems carrying them around. However, they don’t come with a pouch or a case to protect them.
The KZ ZST feel slightly cheaper-made than the other KZ headphones like the KZ ZS10, KZ AS10, or the KZ ZSN. There is a clear distinction between the backplate of the earbud and the earbud frame itself while other models feel like one solid unit. The plastic also feels fairly thinner and doesn't look like it would be able to survive the same amount of pressure before breaking as the other models. On the upside, even this very affordable option has a detachable and replaceable cable, which makes them more durable. You can also buy a Bluetooth adapter cable for these headphones to make them wireless.
Like most ear-hook designed headphones, the KZ ZST are stable, and you should be able to jog with these without any problem. They don’t move around in your ear and should be fine for most light sports. However, the cable might get stuck on something, yanking the headphones out of your ears or hurting you because of the ear-hook design.
The KZ ZST are acceptable-sounding closed-back in-ears that have a fairly similar frequency response to that of the KZ ZSN. They have a deep, powerful, and consistent bass on top of a good mid-range. Unfortunately, their treble is a bit uneven and the mid-range is a bit recessed, pushing the vocals and lead instruments to the back of the mix. Overall, these headphones will be better suited for bass-heavy genres, and the similar KZ ZS10 and KZ AS10 will be more neutral-sounding options.
The bass of the KZ ZST is great. LFE (low-frequency extension) is at 14Hz, which is excellent. Low-bass follows our neutral target very well, meaning these headphones produce just the right amount of thump and rumble, which is common to bass-heavy music and sound effects. Mid-bass, responsible for the body of bass guitars and the punch of kick drums, is fairly flat and within a dB of our curve as well. High-bass, responsible for warmth, is overemphasized by more than 3dB, making the bass of these headphones a bit boomy and muddy.
The ZST’s treble performance is okay. The response throughout the range is fairly uneven. The 4dB overemphasis in the low-treble will add too much detail and brightness to vocals and leads. On the other hand, the broad drip in mid-treble will make sibilants (S and T sounds) in those frequencies quite lacking in detail while the peak around 9-10kHz will make them overly sharp and piercing, especially on already bright tracks. However, not everybody experiences treble frequencies the same, so your listening experience may vary.
These headphones have excellent imaging. Their weighted group delay value is 0.18, which is very good. This results in a tight and fast bass and clear trebles. The L/R drivers of our test unit also showed very good matching, which helps with proper placement and localization of instruments and sound effects (like footsteps) in the stereo image. However, these results are only valid for our unit, and yours may perform differently.
The soundstage is poor. This is because creating an out-of-head and speaker-like soundstage is largely dependent on activating the resonances of the pinna (outer ear). The design of in-ears and earbuds is in such a way that fully bypasses the pinna and doesn't interact with it. Also, because these headphones have a closed-back enclosure, their soundstage won't be perceived to be as open as that of open-back earbuds like the Apple AirPods 2 2019, Google Pixel Buds, or the Bose SoundSport Free.
The harmonic distortion of the KZ ZST is okay. THD in the bass range is within very good limits, but it gets noticeably elevated in the mid and treble ranges. The sharp peaks shown on the graph could result in these frequencies sounding harsh and impure, which may become fatiguing after a while. On the upside, there is no big jump in THD at 100dB SPL, which could be due to the drivers’ flexibility under heavier loads or be caused by the noise floor of our test.
The KZ ZST have decent isolation performance. Since they only block noise passively they don't do much against the deep rumble of plane and bus engines, so they won't be ideal for commuting. However, they’ll be decent against work environment noises. They fit differently than the KZ AS10 and KZ ZS10, and since their bud design is smaller, it seems to be less isolating. On the upside, the in-ear design doesn’t leak too much at higher volumes, so you should be able to block more ambient noise by raising your listening volume without bothering people surrounding you.
The isolation performance of the KZ ZST is acceptable. In the bass range, where the rumble of airplane and bus engines sits, they achieved about 2dB of isolation, which is inadequate and won’t be great for public transit. In the mid-range, important for blocking out speech, they reduce outside noise by more than 15dB, which is good. In the treble range, occupied by sharp S and T sounds and A/C noise, they isolate by 31dB, which is quite good. The KZ ZS10 and KZ AS10 have a better isolation performance overall.
The leakage performance of the ZST is great. These in-ears do not leak in the bass and mid ranges, and their leakage is concentrated in a narrow range in the treble range. Therefore, their leakage will be thin and sharp-sounding. The overall level of the leakage is quiet too. With the music at 100dB SPL, the leakage at 1 foot away averages at 32dB SPL and peaks at 55dB SPL, which is just over the noise floor of an average office.
The KZ ZST headphones we tested didn't have an in-line microphone, but there is a variant with one. For wired headphones with a good in-line microphone, check out the 1More Triple Driver In-Ear or the Apple EarPods.
The KZ ZST headphones are passive headphones which means they do not have any active features and do not have a battery. They also don't have a dedicated app for added customization options.
Like the KZ headphones we’ve reviewed so far, the ZST are straightforward wired in-ears that can only be used passively by default. You get audio support on any platform that has the appropriate 1/8” audio jack. Although this means that your range will be limited by the short cable’s length, you won’t have any latency for video content and games, which is great. You can also buy a Bluetooth adapter cable for these headphones to make them wireless.
The KZ ZST Hybrid are passable in-ears that set themselves apart by the value they offer. They are very affordable but feel slightly cheaper than the other headphones in the KZ lineup we’ve tested so far. Some may feel like they are overly sharp and don’t passively isolate noise as well as other KZ headphones. See our recommendations for the best noise cancelling earbuds, the best wired headphones, the best cheap earbuds, and the best earbuds under $20.
The KZ ZSN and KZ ZST are very similar headphones with slight differences. The ZSN feel a bit more high-end thanks to the metal-like backplate on their earbuds. Some may find them overly sharp, but both headphones have very similar sound profiles. That said, the treble of the ZSN is more uneven. Other than that, they are practically identical and your choice will rely on which headphones you think look the best.
The KZ ZS10 are better headphones than the KZ ZST. Their earbud casings feel better made and sturdier than the ZST’s. Also, their sound profile follows our target curve better and will sound noticeably better in the treble range. Overall, both headphones still have very similar sound quality. On the other hand, the ZST are more affordable and could offer a better overall value for most people.
The KZ AS10 will be a better option than the KZ ZST. Their overall build feels slightly better made than the ZST and their sound is more accurate for critical listening. Also, their fit is better at isolating noise, so they’ll also be more versatile if you want to use them for commuting. On the other hand, the KZ ZST are noticeably more affordable and offer great value.
The KZ ZST are better headphones than the Apple EarPods. Their sound is better, and they also feel noticeably sturdier. However, some will prefer the one-size-fits-all design of the EarPods, which seems to be more comfortable than the in-ear fit of the ZST. Also, the EarPods have an open design, so this means they don’t block noise well and won’t be a good option for commuting. On the upside, they have an in-line remote and microphone, which the ZST model we’ve tested is lacking, though there is a variant that has them.
The Skullcandy Jib Wireless are better mixed-usage headphones than the KZ ZST. Their wireless design makes them more versatile and noticeably better for sports. They also have a microphone and controls, which our model of the ZST lacks. On the other hand, the ZST are noticeably better built and feel more durable than the cheap, plasticky Skullcandy Jib. Also, the wired ZST won’t give you any latency issues, while the Jib Bluetooth connection might result in a noticeable delay.