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KZ ZST X: like Mr. Toad's Wild Ride...

Updated: Dec 27, 2020

Hey guys and gals!

Welcome back to the Neighborhood. Per usual, its Your Friendly Neighborhood Reviewer with InToit Reviews.

Today we’ve got a chance to look at a very unique IEM. The KZ ZST X. Let me say right off the bat, that this is not an accurate IEM. Most definitely not. In fact, it’s a bit of an “odd duck.” But, in any case, it is an experience, and isn’t that what some of us really want from our audio?

So, let’s get InToit!

Disclaimer: And for transparency, the unit was provided to me by KeepHiFi for review and critique, but I am not being influenced by them to say anything specifically, and all opinions and recommendations are my own.

The KZ ZST X is the latest iteration of the KZ ZST. Other iterations of the ZST label include the ZST and the KST Pro. It’s been a while since I’ve heard any of these, but generally speaking, those weren’t very good. So what about these (KZ ZST X)?

Well starting with the build, the KZ ZST X is hybrid, balanced armature and 10 mm dynamic combination housed within a relatively small plastic shell. It comes in two colors at the moment; the translucent electric mint green or translucent electric blue with a fuchsia faceplate. I was provided with the electric green color. The moniker: “ZST X” is screen printed across the front of each of the faceplates. These come with the KZ Starline tips installed, and I had zero desire to swap them out or experiment with alternative tips here. They fit extremely well in my ears, were extremely light weight, and I could instantly tell that I could wear these for hours without any comfort issues. The fit even better than the KBEAR KS2 I recently reviewed as well.

The cable may be the best KZ cable that I have yet to encounter to date. It appears to be over the silver-coated copper variety. It’s soft to the touch, and lays relatively flat, even right out of the box… Why can’t all KZ Cables be like this one? It’s like a T2 Plus cable and a KZ cable had a baby. The ear hooks are a little aggressive, but I barely noticed when wearing them. For the price of this thing of this thing, this cable is excellent. Which is a good thing, because it initiates at the IEM in an odd, square 2-pin, where the housing of the connector recesses into the IEM itself. Like other KZ cables, this one terminates in an angled 3.5 mm, which I mostly don’t like because it makes it difficult to fit it on phones or tablets with larger cases on them. Nevertheless, this particular cable fits on my phone with its case on just fine, so I suppose I should have less of a gripe here. Did I mention that these typically cost less than $20 bucks? For that price, I ultimately feel like you’re getting a good solid package here that is well matched to this set in particular.

Now let’s talk about the sound. It is … different… and like I already said it’s a bit of an odd duck, specially in many ways. Generally speaking, these sound like one is stoned out of their mind, listening to music on festival PA system. Are they the most refined things, no, but they do some unique and interesting things.

Let’s get more specific. We’ll start with the soundstage. It’s pretty great! For an IEM under $20 dollars, this may be the best stage I’ve heard in terms of its general width and depth; however, some of the upper mid frequencies do seem more boxed in, and forward than the rest. Peripheral details were inconsistent- sometimes more forward, while at other times, more recessed. But this also made for some interesting sonics, and, on certain songs, these little guys really did shine. On the song “One Headlight” by the Wallflowers, the tremoloed guitar at the beginning echoes eerily across the whole stage, and depicts that these, in general, have a bit of reverb to them. While one might traditionally consider this a bad thing, remember, these are only for fun, and as such, I’d say that these have an appropriate amount of reverb for their presentation style. These remind me of an Dan Electric Dan Echo pedal on the guitar, which has a unique reverb tone and style to it, which man guitar players adore. And like those musicians, I adore this reverbrative quality here in the ZST X.

Perhaps because of its reverbative character, transient decay is pretty stellar for the price of these things, and details are also quite good- even if their location in space is pretty inaccurate and “all over the place” in the end. In other words, imaging is good with decent definition and separation, but placement is inaccurate. Vocal presentation was also all over the place, with male and lower, timbred vocals being more forward than female singers quite often. Resolution for $20 dollars was quite impressive as well, but cheaper sets are becoming more and more resolving by the day it seems, so I would most simply sum up the resolution here as being above average for its price. Oddly, background noises in some tracks, especially ones which I typically find to be under emphasized, are presented as more forward than the sound engineer probably intended them to be. For example, on the song “100x” by Tegan and Sara, the ambient mic hiss presented as more prominent in the mix than what I have come to expect on that track.

The treble is most defiantly rolled off at its top-end, and these depict a surprising amount of warmth in their overall character at times, despite their balanced armature and the fact that the upper mids come across as assertively forward quite often. Notwithstanding its aggressive character in this region, I never found the ZST X to be sharp, sibilant, or overly offensive, either; but I will say they are somewhat intense in their upper mid-range presentation. A good depiction of said sonics is “Look What the Cat Dragged In” by Poison, which is a track that can sometimes come across as harsh, but instead comes across as unexpectedly warm on the ZST X. Interestingly, I found guitar tones and other instruments within their spectrum to be more forwardly shouty than vocals in the ZST X, even though vocals did have some intensity to them at times.

The bass is somewhat boomy, bloomy, and wooly, but not in an overly intense way. Driver integration isn’t the best here, and the bass overall is somewhat odd with regard to its presentation overall. Unlike most music where the bass appears to come from the “ground up,” in the ZST X, it appears to perceptually “rain down” upon the music instead. There is decent sub-bass presence and rumble, and these are more of a sub-bass than a mid-bass emphasis; but there is also some roll-off towards the bottom. As a result, impact and slam are somewhat limited, as this IEM presents with more of a diffuse pattern to its low-end. Negatively, there is some bass bleed into the mid-range here, but, at the same time, it is less offensive than other sets I have heard. Nevertheless, I never found the ZST X’s bass, nor its other sonics to be fatiguing, even after extended listening periods.

In the end, I feel that I should not like these, but ultimately, I do. I find them to be enjoyable in a guilty pleasure kind of way, but I definitely need to be in the right head space to get the most out of this set. If you are expecting a straight forward, technically competent set, these are not it. They are a bit of an odd duck and an interesting experience to say the least, but they are also fun. I would not recommend these as an everyday driver, or go to IEM; however, but as part of a collection, they will be fun for IEM enthusiasts to pull out and listen to if one is in the right frame of mind. In my opinion, it would take a special person for these to fit their needs as their primary listening set. In some ways they are like Mr. Toad's Wild Ride, its trippy and lack sophistication, but enjoyable nevertheless. Sometimes words don’t really articulate an experience as well as an image, so I’ll include a GIF below that I think accurately depicts the KZ ZST X experience.

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