Review - Kiwi Ears Allegro

Review - KZ ZSN Pro X (sub 50€)

English | Español
Also available on YouTube in Spanish: Acho Reviews YouTube 

In the past I purchased the KZ ZSN, the ZSN Pro and when I saw the ZSN Pro X, another 20€ hybrid IEM from KZ, I thought, why not?

I actually enjoyed the original ZSN but found the Pro to be to bright and sibilant, so maybe the Pro X would again be enjoyable?

KZ claim that this IEM is based on the ZSN Pro but with an improved high frequency balanced armature driver and a 10mm low frequency dynamic driver. They say that the “the flexible lows and smooth mids plus the bright highs are perfectly combined by scientific adjustments, giving the human voice richer and clearer details.”

Sounds like the rest of the ZSN marketing to me, so how could I not dig out the older models to compare at the same time?


It must be more than a year since I purchased the ZSN Pro and even longer since I purchased the ZSN but nothing has changed as far as presentation.

In the typical white box from KZ, we get the IEMs, the cable and a selection of tips.

I believe that the tips may be slightly different from the ones included with the older revisions but I can’t confirm as I have all the tips thrown in one big box, making it impossible to be sure which tips came with what.

The cable I got with this version has an inline microphone whereas the previous ones didn’t, so the cable is slightly different, mainly because of the microphone and because it is white (other than that, it is the typical KZ cable). I didn’t plan on using the included cable anyway, so I haven’t tried it.

That’s it as far as contents.

Build and aesthetics…

Again, nothing has changed here. If we look at the photo of all 3 ZSN models in a line, they are pretty much identical except for the colour and the fact that the original ZSN had the lines sunken in rather than protruding as they are on the Pro and Pro X.

The inside of the shell is a transparent resin that is coloured, whereas the back is a metal plate.

All three models use the KZ connector style that sticks out from the shell, I believe they call it type C. So again, no change.

On the resin shell, in the typical style of KZ, there is the name of the model plus a small description underneath. In the case of the ZSN Pro X, it states “New Hybrid Drivers” (the original ZSN said “Balanced Armature” and the ZSN Pro proclaimed “Classic Upgrade”.

As you have probably guessed, the comfort is identical on all three, so if you find one of them comfortable, you will have no issues with any of them.

As far as durability, I haven’t had any issues with any of the KZ models over the past couple of years so I have no reason to think this one will be any different, but I guess only time will tell.


As I said at the beginning, I enjoyed the original ZSN. It wasn’t the most detailed of earphones but it’s sound signature was quite pleasant and relaxed without really going overboard in any of the frequencies.

The Pro I didn’t enjoy so much. It was still no better than the original as far as detail and the sound signature changed from relaxed to bright and sibilant, at least with the majority of music.

However, it has been a long time since I listened to either of the ZSN variants, so revisiting them together with the ZSN Pro X has been like trying out 3 new IEMs at the same time. In order to abbreviate which model I am talking about, I will simply refer to them as the OG (the original ZSN), the Pro (the ZSN Pro) and the X (the ZSN Pro X).

Starting off with the bass, the X is a huge step up from either of the previous models and is by no means short on bass.

Extending quite far down into the sub bass regions, it gives the necessary rumble on tracks like “Bury a Friend” and “No Mercy”. It extends far more into these regions than either or the other two versions, and is in fact probably the KZ with most sub bass rumble I have heard so far, maybe only matched by the S2 (the bluetooth IEM I previously reviewed).

In the higher bass frequencies, there is again a lot of presence and plenty of “slam”, for lack of another word to describe it better. In songs with hard hitting kick drums, these are presented in a way that gives you an impression of air hitting the mic. In fact, on many tracks, such as “Royals” by Lorde or “I Fink U Freeky” by Die Antwoord, I found the bass to be overly present and could actually become tiresome when you are not looking for that bass heaviness. In comparison to the T2 plus for example, an IEM that I found to have plenty of bass when needed but absent when not, I find the X to have too much and would actually prefer to remove some of that excessiveness via EQ.

In comparison to the OG or the Pro, the X has much more bass, in all of it’s lower frequencies, and while it can seem very impressive at first, I like it a little more tamed back for the majority of my music preferences and would prefer the quantity found on the OG (I find the Pro to be lacking).

Moving on to the mids, the lower part of the mids does suffer due to the powerful bass. I don’t think that it is recessed in any way, just that it becomes part of the excessive bass that is present on some songs. This makes it difficult to track instruments in the lower mid frequencies, and while it doesn’t get too muddy, it isn’t very clear either. In this regard I would say that both the OG and the Pro behave better in the lower mids, due to there being less bass to bleed into them.

In the higher mid region, the X can go from recessed to rather shouty. In songs that are usually pretty balanced in the bass range, such as “Billie Jean” by Michael Jackson or “Bombtrack” by Rage Against The Machine, vocals can still seem to get lost behind the instruments that sit in the lower regions. However, in songs with powerful vocals, especially female vocals, the IEM can become very shouty and even give the sensation of being overly present and even distorted at times. This is noticeable in parts of songs that are more powerful in certain sections, such as the busy part of “Hello” by Adele or “No One” by Alicia Keys. In fact in songs like these, it is possible to go from recessed to overpowering in just a few bars.

In the higher mids, again the OG and X seem to do a better job of maintaining the calm, however, if I had to choose, I would go with the OG in this range.

Moving up into the higher frequencies, the X is not as sibilant as the Pro, but it is still too sibilant for my preference. The X seems to have a boost slightly lower than the Pro, resulting more in a shouty sound than a sibilant one. Saying that, my typical sibilance test, such as “Hope Is A Dangerous Thing” by Lana Del Rey or “Code Cool” by Patricia Barber are too sibilant for me to enjoy.

There is also a slight metallic ring in the treble which is common on the majority of BA IEMs and I have found in different quantities on all KZ models I have tried. The X doesn’t seem as metallic as the OG or the Pro but it is still there.

As far as speed and detail, the X gives a sense of both when first listening to it, but starts to fall apart on fast and complicated tracks, such as “The Room” by Ostura. I think the range that suffers the least is the bass range, which actually manages to hold itself together pretty well for such a boosted zone. The OG and Pro are no better though and I wouldn’t give any of them high marks in this regard.

The soundstage is pretty much what I have found on most IEMs that I have tried. It is not very wide but is not terrible. In the typical test track which is “Letter” by Yosi Horikawa, the width is not huge but placement is actually pretty decent. I would say that the X does not fall behind the OG or the Pro in this regard.


I can’t say that I have really enjoyed the third offering in the ZSN line, to be honest, I have found it quite tiring. It is not a bad IEM for it’s price of 20€ and may suit the preferences of those that are looking for a V shaped sound signature, some may find the powerful slam of the bass impressive, however it would not be my personal recommendation over so many other alternatives in similar price ranges.

In comparison to the original ZSN, which is now available for around 10€, I find the OG more relaxed and pleasing for my tastes in music. The X does seem to give a sensation of more detail but that soon gets lost when music gets busy as everything seems to become one big wall of sound.

In comparison to the ZSN Pro, which is now available for less than 7€, I personally wouldn’t choose either. If I had to, then I would choose the X as it is slightly less sibilant and has more bass, but it would be a case of the “least bad” of the two.

It is worth noting that all of the tests above have been made with the large “star” type silicone tips included with the ZSN Pro X. I did swap over to my preferred foam tips and it tamed the bass a little and stopped the voices from getting so lost in the background, although they are still recessed. However, it did not fix the sibilance, nor did it convert the sound signature enough for me to find it pleasing. I would say that the X does improve with foam tips, but still not enough to recommend it over other items at similar prices.

My simple explanation of the ZSN Pro X sound would be… dirty. That probably doesn’t make any sense but that is the impression that it gave me. It is as though all the frequencies of the IEM are competing against each other instead of working with each other.

As far as competing with other sub 50€ contenders, it is way behind. The T2 Plus in comparison seems like a completely different level.

All FR measurements of IEMs can be viewed and compared on
All isolation measurements of IEMs can be found on

To comment or contact, visit any of the following social media platforms: