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KZ ZSN Pro X
The internet is flooded with all sorts of newcomers to audio products, and it has never been more overwhelming to parse the junk from the gold. Sure, the reliable standbys are out there, but the bargain hunters willing to take a chance on inexpensive unknowns might get a dud or a diamond in the rough. KZ is a popular brand among budget audiophiles and it produces a dizzying roster of earbuds—all with equally dizzying names. We spent a week with the KZ ZSN Pro X to see what kind of performance you can get out of $30 USD earphones. It’s better than you might expect.
Editor’s note: this KZ ZSN Pro X review was updated on April 18, 2023, to answer frequently asked questions (FAQ), and to update formatting.
Anyone who wants a pretty good set of wired earbuds will like the overall performance from KZ’s earbuds. More specifically, bargain hunters can feel the satisfaction of getting a deal when they buy the ZSN Pro X. Plus, folks who prize sound quality the most will like this headset’s frequency response.
What’s it like to use the KZ ZSN Pro X?
The ZSN Pro X ships either with a mic cable or a simple audio-only cable. The underbelly of each earbud housing has a smoky translucent acrylic finish and the shell comes in black or gold. In person, the metal outer shells look alright, but not as refined as on the KZ product page. Keep in mind the ZSN Pro X sells for less than $30 USD, so having color choices is kind of a bonus.
The simple packaging includes the gold and clear plastic buds, as well as four sets of silicone ear tips. These range from 10mm up to about 14mm in diameter. Spend some time really sorting out your fit, because so much of the comfort and sound quality relies on a secure fit. I find that a combo of the 12mm ear tip (left) with the 14mm ear tip (right) fits better than when I use the same size for both ears—everyone’s anatomy is different.
The cable guides your fit, as the plastic wrap is bent in a shape to curve over the top of your ear. This keeps the KZ ZSN Pro X stable, though the seam of the plastic irritates my skin after some time. On the whole, the ZSN Pro X is neither the most comfortable, nor the least comfortable set of wired earbuds I’ve tried. I rate the comfort as mostly fine, due to the right bud pushing somewhat on my helix. Folks with small ears might struggle to get a fit that feels good over long sessions.
How do you control the KZ ZSN Pro X?
The ZSN Pro X has a single button control that is also where the in-line microphone resides. In tests when used with a USB-C dongle connected to an Android phone, the single and double-press commands work most of the time. Sometimes if another app is open, the commands don’t reliably work. Unfortunately, the triple-press command to skip back to the previous track does not register correctly and instead registers as a skip forward. The commands for phone calls, on the other hand, function without issue.
| 1 PRESS | DOUBLE PRESS | TRIPLE PRESS | PRESS AND HOLD | |
|---|---|---|---|---|
MULTI-FUNCTION BUTTON | 1 PRESS Play/Pause Answer call/End call | DOUBLE PRESS Skip forward | TRIPLE PRESS Skip to previous | PRESS AND HOLD Reject call |
How do you connect the KZ ZSN Pro X?
This one is pretty simple: you connect the KZ ZSN Pro X by plugging it into a 3.5mm headphone jack. You should make sure that the cable is plugged into the housing correctly because the two prongs can easily be swapped the wrong way around. The included removable cable is a 2-pin design, which tends to be cheaper to produce than MMCX, easier to plug in wrong, and easier to accidentally bend the pins. With that said, I find unplugging it from the buds demands less force than most MMCX earbuds.
If you want to add Bluetooth connectivity to your KZ ZSN Pro X earphones, you can purchase a separate KZ AZ09-C Bluetooth module, or the aptX codec-equipped KZ AZ10-C and unplug the included cable and swap it out. This turns the wired earbuds into true wireless earbuds that hook around the ear, and costs about as much as the ZSN Pro X alone. We haven’t tested a set and can’t comment on the implementation.
No, with a sensitivity of 112dB and an impedance of 25Ω most standard headphone outputs can easily drive the KZ ZSN Pro X without needing an amp. However, if you match your ZSN Pro X with a modern day phone, there’s a good chance you’ll need a DAC.
How well does the KZ ZSN Pro X block out noise?
The passive isolation of the KZ ZSN Pro X is fine. It blocks a small amount of low end, which passive isolation typically doesn’t excel at. More importantly, in the highs, it hovers between 20-40dB in attenuation. This is useful for environmental intermittent clangs or muffling speech. It’s pretty average and your particular experience relies on how well you can get the buds to fit. If you want to increase isolation, consider purchasing a third-party set of memory foam ear tips, and for reference, the stems of the buds are 5mm in size.
How does the KZ ZSN Pro X sound?
The KZ ZSN Pro X surprises us with its very good frequency response. It follows our target curve closely, only deviating within a couple of decibels across the spectrum besides a small bump at 5kHz where it only exceeds by about 5dB—this lends itself to slightly louder treble reproduction than our ideal. Ultimately, the vast majority of consumers will like what they hear from the ZSN Pro X.
Using a hybrid of 10mm dynamic drivers and balanced armatures means KZ can delegate specific frequencies to each. The stated frequency range is 7Hz-40kHz, but keep in mind you pretty much won’t hear most of that extended range in the lowest lows and highest highs. Distortion (THD) is pretty low as well. Seriously, the ZSN Pro X sounds much better than its price suggests.
High, mids, lows
Listening to La Rheinita by La Düsseldorf is a joyful experience. The warbling phaser filter over the synths is the perfect volume in concert with the low kick and tom-heavy motor-rhythmic beat. Crash cymbals that intermittently punctuate the track are at a pleasant volume, as are the piano chords. At no point do I wish I could hear something louder, while the ZSN Pro X tends to favor higher frequencies. For those with extra sensitive hearing, this 5kHz volume spike could veer into “ear-piercing treble territory,” though it seems acceptable.
The ZSN Pro X has an unusually good frequency response for budget earphones.
Guilty by Lady Wray is vocal-focused and her soulful voice comes through well enough, I just wish it was a tad louder. This might be related to the very slight under-emphasis between 300Hz-1kHz. The hard-panned guitar parts can be a little loud relative to Lady Wray’s vocals, particularly in the first verse. All the drums, meanwhile, sound about spot on.
While the bass guitar is completely audible, it doesn’t quite propel the song with the same oomph I’ve heard this song have on other headsets. Honestly, for what it is, I would not alter the frequency response, but it’s not the most bass-heavy option out there.
How does the microphone of the KZ ZSN Pro X sound?
Like all in-line microphones, how the KZ ZSN Pro X sounds depends on how far the mic is from your mouth. During a phone call, a friend says my voice sounds clear but quiet. When I lift the mic closer to my mouth, the volume issue disappears. That’s not ideal, since moving and holding the mic in place means talking on the phone is no longer a hands-free experience.
In our tests the ZSN Pro X mic sounds pretty clear, though it can make voices a little too sibilant (s sounds). The mic also picks up plenty of environmental noise, as demonstrated in our street and wind samples, but your voice will still come through well, provided your mouth is not too distant.
KZ ZSN Pro X microphone demo (Ideal conditions):
KZ ZSN Pro X microphone demo (Street conditions):
KZ ZSN Pro X microphone demo (Windy conditions):
How does the microphone sound to you?
Should you buy the KZ ZSN Pro X?
Anyone looking for a wired set of earbuds could do much worse than the KZ ZSN Pro X. Trying the ZSN Pro X really makes me want to try other Knowledge Zenith (KZ) products. It’s not perfect, however, anyone looking for a set of cheap wired earbuds could find some fun with the ZSN Pro X. Its sound quality is very nice, and it fits reasonably well. At less than $30 it’s a worthy experiment.
For some, the housing will be too large to fit easily in all ear sizes. The over-the-ear cabling is useful but can irritate skin with the plastic seams during long sessions. You can replace the 2-pin cables, which is more than can be said for a lot of other cheap earphones. It’s not chockful with the latest and greatest technology, like Bluetooth and uses some older tech like the 2-pin cable, but for the sound and the price, the value is fantastic.
One thing to keep in mind with KZ is that while the ZSN Pro X works (save for the “skip to the previous track” control), we purchased a different KZ unit that arrived and simply did not work. We can’t say for certain if this is common. All manufacturers have some percentage of failed units, but make sure you purchase from a reputable seller just in case you’re unlucky.
What should you get instead of the KZ ZSN Pro X?
For even less money—really only a few bucks difference—the Moondrop Chu features excellent sound quality coupled with low distortion (THD). It lacks removable cables found on the KZ ZSN Pro X, and utilizes a somewhat do-it-yourself set of sleeves to guide the cabling over your ears. Besides that, at any price the Moondrop Chu is tough competition for the KZ ZSN Pro X for $21 at Amazon.
If you want a more neutral studio-style set of wired earphones, you can give the Tin HiFi T2 a try. It sells for $49 at Amazon and provides a less bassy frequency response that’s useful for monitoring audio. The fit is kind of clunky but like KZ, the sound quality is better than the price suggests.
For roughly the same price as the KZ ZSN Pro X you can still pick up the (discontinued) JBL Quantum 50 ($34 at Amazon). Like the ZSN Pro X, the Quantum 50 has a very nice sounding frequency response with a tad more bass. For gamers out there, it has the added advantage of working as a set of wired gaming earbuds too. The build is decidedly plastic and you can’t swap out the cable, but it ought to fit most ears comfortably.
Frequently asked questions about the KZ ZSN Pro X
The initials stand for “Knowledge Zenith” and also happens to be the founders’ initials.
Because the ZSN Pro X has no waterproofing, you have to be careful not to get the buds too damp, so just get a swab, some gentle dish soap, and a bit of water. There’s more to cleaning earbuds, but that’s the gist.
Nope, our ears can’t hear that high or that low. In addition, that range doesn’t suggest if the output at those frequencies is even audible.
Not having reviewed other KZ products, we can’t definitively comment on the sound quality of any besides the KZ ZSN Pro X. Fortunately, the KZ ZSN Pro X usually retails for under $35 USD, and it sounds rather good. If you don’t mind looking at other brands, the Moondrop Chu also sounds great and is similarly priced.
The KZ ZSN Pro X is rather different from the Skullcandy Jib+ Wireless. For starters, the KZ ZSN Pro X is a wired pair of earbuds without any sweatproofing, and does not come with Bluetooth compatibility as in the case of the Skullcandy Jib+ Wireless. Aimed at workouts the Skullcandy Jib+ Wireless doesn’t cover the same niche as the KZ ZSN Pro X, which is meant for close and casual listening with an emphasis on sound quality. Both are relatively inexpensive, but the right choice depends on if you want affordable wireless earbuds or wired earbuds, and if you need an IP rating.