KZ ZSX

It’s difficult to keep track of how many IEMs KZ have launched in a month.

Or so was the case before the launch of the KZ ZSX — dubbed as the “Terminator” by KZ themselves. Whether it terminates the competition, or merely the rest of the KZ lineup is the question.

This is the first time I will formally review a KZ IEM, as apart from the KZ ATE all their IEMs since then have been various forms of meh. They are not bad in terms of specs, as KZ seems to be very intent on winning the driver-count war (as useless as the megapixel war in smartphones). While the sound didn’t noticeably improve for the most part, their marketing team had a field day with the increased driver count, and so with the ZSX we’ve got 12 drivers (!), though that’s basically 6 drivers on one side…

So yes, none of it makes sense. Let’s just get on with the review.

[ You can read a better formatted version of this review on my blog. ]

Note: the ratings given will be subjective to the price tier. Definitely the expectations from a $15 IEM won’t be the same as a $150 one, and that’s the approach taken while assigning scores. I bought the IEMs with my own funds, still, Disclaimer

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Sources used: LG G7, Questyle QP1R

Build: The build quality is a mixed bag with the ZSX. The face-plate is something that I find nicely finished, even though it tends to retain smudges. The issue is the resin shell as it looks really cheap and tacky. While I’m glad that KZ got rid of stupid texts on the IEM shells, the poor finish on the shells don’t do much in hiding their budget roots. The metal nozzle is a nice touch, and the 2-pin connector itself is pretty standard. Inside, there are six drivers — one super-high BA, two mid-high dual-BA (four in total), and a solitary 10mm dynamic driver (presumably responsible for the bass). Do note that all those BA drivers are Bellsing drivers (or similar). No Knowles/Sonion BA here. Also, there seems to be no physical cross-overs in sight, so it’s basically a mix of some slots for the drivers and coaxial placement (for the super-high BA).
Another subjective observation: this is perhaps one of the ugliest IEMs I’ve ever used, period. The design is just… too random. Not that they picked this particular shape due to comfort (more on that later), rather it seems like this is how they could fit all six of those drivers. It just doesn’t seem very appealing to me, and while it is a subjective statement, it does lack of the finesse of some other IEMs at this range.
3.5/5


Accessories: Ah, KZ and their accessories, or the lack thereof. $50 is not necessarily a premium price, but to only have a terrible cable in the packaging and no carrying case — it’s not gonna cut in 2019. KZ has always tried to get away with as poor a cable as possible, and that trend continues even now. Disappointing. Ah well, at least the eartips are decent.
2.5/5



Comfort: Due to the random protrusions from the inner-side of the IEM, these are not comfortable at all. I had to yank them out of my ears after a half hour listening session as they induced some serious pain. This is the first time I’ve had to resort to such measures on an IEM (it only happened once before with the M50X aka torture-cans). The comfort that these IEMs provide are questionable at best and downright unusable at worst. Also, they have poor isolation, so best of luck during your commutes.
2.5/5


Now, on to the sound:

Bass: KZ ZSX has a slightly emphasized mid-bass, and rolled-off sub-bass. The sub-bass roll-off is evident in the lack of rumble. The one odd thing about the bass response is that it sounds somewhat disconnected from the rest of the sound. That is probably down to the lack of a physical cross-over, but there’s no point in speculating much over it. The other, more pressing issue with the bass response is that it lacks the “texture” of other good dynamic drivers. While KZ has used a newer (and apparently better than the previous gen driver) dynamic driver, the texture of the bass is completely lost in the mix. Every bass note sounds the same, there’s no subtle shift in tones. It would be excusable for a $50 IEM a few years back, but times have changed.
3/5

Mids: Midrange has a lower-mid dip that’s not too evident from the graphs but once you start listening to them, this dip stands out. On some lower-pitched male vocals this leads to sense of “compressed” sounding vocals. Case in point: Colin Hay’s I Just Don’t Think I’ll Get Over You has a deep, baritone-like lead vocals with subtle acoustic strums along the way. The subtlety of Hay’s voice is completely lost on the ZSX, as it sounds overly compressed.
On the other end of the spectrum, female vocals can often sound too energetic, depending on the track. Donna Burke’s rendition of Glassy Sky exhibits this issue, and sounds overly bright to my ears. There are also subtle hints of sibilance, though nothing that distracts too much.
String instruments sound fine for the most part, and due to pretty good instrument separation, it might sound really impressive at first listen. It’s only when you start listening to more and varied tracks do the issues crop up. Overall, it’s a pretty decent sounding midrange that falls short of budget-perfection.
4/5

Treble: The treble is where things start to get troublesome as the infamous BA-timbre is on full-display here. The cymbal crashes sound too thin and sharp, as the bump around 7–8KHz is a bit overcooked, and due to the placement of the BA driver inside the nozzle itself — it’s all too distracting at times. For example, Breaking Benjamin’s The Diary of Jane has a lot of cymbal hits in the background, all of which sound unnaturally thin and splashy on the ZSX.
The presence region (~5–6KHz) also has a bump that makes everything sound intense, and I personally cannot listen to the ZSX for long due to this overall bright treble. Coupled with the comfort issues — this is an IEM I find myself taking a break with more often than not, and that’s a shame, as on slower and less heavy tracks the treble is actually rather fine. On heavier genres though, this might be too bright for its own good.
3.5/5


Soundstage: The soundstage is average. Nothing to write home about here. It doesn’t sound claustrophobic, so there’s that.
3/5

Imaging: Usually multi-driver IEMs get an advantage in imaging as the literally separate position of various drivers often grant better localization of certain instruments. It is a similar case with the ZSX as instrument placement is mostly well done.
One strange thing about ZSX’s imaging is that it does the “corner” imaging well, i.e. instruments on top-left/top-right will often sound where they should, but when it comes to panning across the stage, ZSX struggles. On tracks like Godsmack’s Straight Out of Line, the snare hits/guitar distortions often start from left/right and then finishes on the other end. ZSX has this tendency to abruptly shift from left to right instead of a smooth, continuous motion. This might not be too much an issue for many people but certain other IEMs get this correct, so it had to be mentioned.
4.5/5

Bang-for-buck: These are not the absolute-best-bargain-deal. They are a decent set of IEMs that might fit your needs, but you can most likely find something else just as good, if not better, at or around the price point. Also, the accessory set is a huge bummer.
Still, these are not necessarily overpriced, so there’s that.
3.5/5


Source and Amping: Make sure that your output device has less than 1–1.5ohm of impedance, as otherwise the ZSX will exhibit some odd behaviors. This is an old issue with many multi-BA IEMs, so nothing unique with the ZSX. Fortunately enough, most of the mobile phones/dongles have really low output-impedance and due to the very high sensitivity of the ZSX they will run just fine on those devices.


Select Comparisons

vs Tin HiFi T3: Tin T3 has recently been superceded by the T4, but Tin HiFi is still selling them around the same price as the ZSX. For one, the T3 is built much better, and the accessories are of significantly higher quality. The cable especially is on another level.
In terms of build quality, T3 has the upper hand, and the same goes for comfort.
As for the all-important sound quality, T3 has a leaner presentation with much thinner bass notes that lack even more sub-bass impact. The mid-range is also noticeably leaner on the T3. Treble, however, is smoother and better defined for my tastes on the T3. If you need a more energetic, on-your-face sound then ZSX is the way to go. Or if you prefer a more analytical signature, T3 might be the better option.

vs BLON BL-03: This is the comparison that everyone wants, so let’s just get into it. Both of the IEMs have terrible accessories, so it’s a tie. BLON however requires that you get a pair of 3rd party eartips, so there’s that added cost (though even with a pair of Spinfits it costs less than the ZSX retail).
Then, there is comfort, and with proper tips the BL-03 is more comfortable. Both have similarly poor isolation so it’s a tie.
Sound signature is where they are very different. BLON BL-03 focuses on a more measured approach and attempts to strike a beautiful balance between the bass, mids and highs. It largely succeeds as well, since you get a really punchy bass that doesn’t bleed into the mids, fantastic vocal rendition (esp female) and a smooth-yet-sparkly treble that delivers some air and shimmer around the upper-treble.
ZSX is all about an up-front signature. This works well with genres like Rock where distortion guitars and raspy vocals take center-stage. However, with heavier genres like Metal the bright treble might be a bit too hot to handle. Also the bass is definitely a step down from the BLONs.
If I had to pick between one of them — it will be the BLON BL-03 hands down, but that’s just me.


Conclusion:

“Don’t forget, the original intention of using earphone is to enjoy music.”

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That’s what KZ has printed inside the ZSX box.

Well, the ZSX will indeed allow you to enjoy your music, at least some of it. This one is, in my opinion, the best KZ IEM to date. However, the IEM world is not a bubble, as newcomers like BLON has completely redefined the budget IEM range and KZ is already on the back-foot. They have their driver-count marketing trick, but it won’t work for long.

KZ has been manufacturing IEMs for over 5 years and they are wildly successful. Still, I don’t see the ambition there. They are mostly about pushing volumes and not pushing the very definition of budget IEMs, which is a darn shame as their original ATE was one of those budget IEMs that sounded like it costs quite a lot more.

KZ is finally heading in the right direction with the ZSX, as this one is tuned a lot better than their previous stuff. However, pressing issues like poor QC control and a total lack of design awareness still exist.

As for if you should buy the ZSX — try before you buy, and try it for a while. If the comfort is alright and that 5/6KHz peak is not an issue then you can definitely give it a shot. It doesn’t sound terrible, is mostly as coherent as you can expect a $50 IEM to be, and has some nice instrument separation to boot.

However, it won’t be my first recommendation, or the second, not at that price. Too bad.

You can check the current prices here (non-affiliated link).

Test tracks (as YouTube playlist, often updated):

The Terminator is here. The latest KZ ZSX, dubbed, The Terminator, is a 6-driver hybrid in-ear monitor earphone with a single dynamic driver and 5 balanced armature drivers feeding it through a rather large shell. The new shell design has a silver triangular look to it that looks a little strange to me, but feels well made at the same time.

The fit itself is a bit of a problem. It’s larger than other IEMs I’ve tried outside of say the Campfire Solaris and my current daily driver, the qdc Anole VX, and the highly praised Sony IER-Z1R, but it’s in the same realm as those in terms of size. The main issue for me is that the angle of the nozzle spout is not in the most optimal direction for my ear and that its not only long, but also has a large diameter. Now, long nozzle shafts don’t bother me, as something like the Moondrop Kanas Pro is really comfortable for me, and so are things like the Campfire Andromeda Gold and IO. Large diameter IEMs are also not a problem, but the combination of the two, with the angle choice, makes it a tough fit for me, and limits my time wearing these to shorter spurts – much like the issues I faced with the Campfire Solaris previously.


Judgement Day Sound

The ZSX has a full-bodied sound that isn’t too far away from some of my favorite top of the line tunings like the ones presented by Solaris and the IER-Z1R – which both present a warm, balanced sound with treble energy and thick lower mids. Of course, the significantly cheaper KZ ZSX is nowhere near the other two when it comes to things like resolution, speed, imaging, and detail. In fact, its quite a step back, but still, the ZSX is impressive for a product made by KZ and of a $50 price tag.




The bass is punchy and elevated, however not bolstered enough to be considered a super bassy IEM. It has good subbass and a downward slope to the mids that has gives impact to drum kicks and has a mild slam to it – more so than the Solaris did. The bass resolution is pretty mediocre though, and the speed of the driver is a tad slow, leaving bass notes to hang out a little longer than I would like. I do tend to prefer nimble, quick, and agile bass responses that provide plenty of detail and textured layering, and the ZSX sounds more like bass noise than bass resolution.

The mid-range is warm, rich and full of body. I never found the mid-range to be too recessed – in fact, I actually like how it’s presented. Male vocals have girth to it, and female vocals do shine and are forward with a response curve that starts sloping upward at 1KHz and almost follows a Diffuse Field type curve until the about 3.5KHz where it has a small drop. This does help it from being too forward and too harsh for me, and gives it a little bit more breathing room from possible congestion.

There is a slight bit of harshness due to an elevated treble peak that can make things a little spicy at times. I never found it overly bright and fatiguing, but just note that it’s not as smooth sounding in that area as say the Solaris or the VX, which I really both enjoy it’s tuning. It’s more along the lines of the Sony IER-Z1R, with its slightly bright tuning in that area. Again, I’m just using some of these known IEMs as a base line and I am not saying the ZSX is of the same caliber. It’s just a similar overall tuning from a high-level overview shot of the IEM’s sound.




I found the ZSX sounding best with rock and country music. The elevated bass that isn’t over done gives drums and bass guitars the needed bump, while the punchiness gives the kick needed to steer rock songs, while the tuning of the upper-midrange and treble gives clarity to guitars and cymbals. It works well for these popular genres.

Overall

The ZSX is a nice choice for a budget IEM, and easily my favorite of one from KZ. It actually is very similar in tuning to the ZS10 Pro, my previous favorite, but downplays the treble a bit, which makes this one not as harsh and fatiguing as the ZS10 Pro was.



The fit, however, is large and should be something to look out for. It’s not going to fit with some people’s ears, including mine, and that could make this a non-starter to begin with. I do have smaller ear canals than a lot of people, and typically wear small ear tips, so the larger nozzle shape and angle really don’t do me any favors here.

So, if you can deal with that shortcoming and your budget was around $50, and you like this type of tuning, this could be a decent set to look out for. It falls in-line with tuning of some of my favorites, and that’s half the battle for me, and that’s why this was instantly one that I enjoyed when I first heard it.

KZ just keeps turning out top flight earbuds at an outstanding rate and it is getting hard to keep up. It gets to the point that you are going to be guaranteed a certain listenable quality piece for $50 or less, and it's just a question of your preference in tuning and comfort levels. The new KZ ZSX is a perfect example of this phenomenon. This gear bills itself as a 6 driver per side IEM with a newly developed higher frequency balanced armature driver and, like others in this lineup, it is quality made metal face plate and very attractive, although perhaps a little bulky for some. I am not a huge fan of the braided cable that now seems standards on the KZ line, but at least this model had the more comfortable and springy ear wrap at the attachment points, which is a must for me. I can wear these without discomfort despite their weight.

My impression on sound is that this KZ ZSX is a much more mature and less in your face presentation that some of the previous KZs I own, like the ZS10Pro, which is a similarly styled over the ear unit. The ZSX puts the music together is a more holistic way and, after some break in period, I noticed some nuances in male vocals that I hadn't heard in some of my earlier KZ models. When I upgraded to a better source unit, or popped an Audioquest Dragonfly on the iphone, the quality and smooth presentation became more obvious. The sub bass in substantial but well controlled, The mids are clean, nothing spectacular, but the treble stands out as detailed with a nice reach and a touch of sparkle but not in an annoying way. It is simply about as listenable as you are going to get at this price point and a very attractive package as well. I will follow up later after I spend more time with the ZSX.