WATCH REVIEW HERE: https://youtu.be/ek4fCzEV61U

PROS:

• Unique neutral bright sound
• Linear, clean and smooth bass to mids
• Nuanced, full-bodied and clear midrange
• Good detail retrieval
• Competent separation and layering ability
• Very snug fit with no air pressure build-up
• Fantastic presentation and support

CONS:

• A little too revealing that causes occasional sibilance
• Treble contrast is too drastic and affects the timbre
• Closed in sound stage
• Fit might be too aggressive for some
• Very source sensitive
• Lacks bass tactility and impact

WHO THIS UNIT IS FOR:

• People who want a uniquely tuned neutral-bright IEM
• People who want a snug and stable fitting IEM (with bigger ears)
• People who like companies who put a lot of effort into the presentation of their products
• People who like a linear low to midrange presentation

WHO THIS UNIT ISN’T FOR:

• Treble sensitives
• Timbreheads
• People with smaller or weirder shaped ears
• People who want a more “normal” tuned IEM

RECOMMENDED GENRES:

• Jazz
• Orchestra
• Classical
• Ambient

SHORT REVIEW:

Kotori proves themselves a competent company with their latest release being their most mature, best tuned and most capable yet. Their continuous improvement every release is seriously commendable considering that they’ve only been established in 2019. However, they still have quite a lot to improve, particularly with their treble and overall coherency. Once they refine that and release more products, they’ll be legends in the making. Until then, the Zephyr is a set worth considering if you’re looking for a uniquely tuned neutral bright IEM. RECOMMENDED WITH CAVEATS

FULL REVIEW:

Smaller, boutique brands often have the most incentive to try new things. In a competitive market such as in-ear monitors, you have a lot of brands that you need to topple or at least prove that your product can compete at the price you ask for. 

However, 90% of the time it ends up being a flex product or a creator-support product rather than something that is actually unique and usable. But when you’re a company obsessed with improvement and actually care about the quality of your product, you’re bound to make a product that is both boutique and unique. 

Let’s talk about the Kotori Audio Zephyr. 

FLY AWAY ON MY ZEPHYR!

I fully respect Kotori for a few reasons. In my previous review of the Kotori Vampire, I noted that they created this “reviewers guide” that is less about telling what the reviewer should say and instead actually guiding them by explaining the thought process of the product from development to specifications. That’s probably the one thing that sets Kotori apart from every single company that I’ve come across. But for a boutique brand from Singapore, you have to make this effort, right?

The set today is the Kotori Zephyr, a DD + BA hybrid priced at $150 and is their 3rd product following the aforementioned Vampire. This is also their most expensive IEM to date, but for good reason that we’ll talk about later. So how exactly does this Zephyr soar through the competition?

Let’s start with the unboxing

UNBOXING

Sophisticated is probably the best way I can describe the unboxing experience of Kotori Audio products. Maybe it’s a trend, but smaller brands seem to offer much more than just the IEM in their unboxing. They want you to have an experience from the moment you receive your IEM until they reach your earlobes. 

Here’s a full list of the inclusions:

• IEMs
• Cable
• Metal Case
• Eartips with case
• Paperwork

While not necessarily mind blowing for the price, you get what you need and nothing more with the Zephyr. The eartips are serviceable, but I highly recommend tip rolling as we’ll talk about the sensitivity of the sound later. 

The case is your usual metal round case that holds the IEM and maybe a few eartips, but not really much more than that. 

I do appreciate the quality of their paperwork. If anything, it really makes it stand out from a lot of the brands I come across with how meticulous they are to every part of their package.

BUILD & FIT

Now let’s get to the fun part. The Zephyr was created with two things in mind; improve upon the acoustic system of their first IEM called the Dauntless and use the feedback they received from the Vampire. And quite frankly, they nailed it. 

But let’s talk about the internals first. 

The Zephyr features a single titanium dynamic driver paired with a Knowles balanced armature driver. Not necessarily a new pairing, not by a long shot and not at this price point, but it holds a rather special tech that Kotori seems to have called their own. 

PBAS Implementation

I’ll let them explain what the PBAS in their own words:

• The PBAS is a step up from a similar system previously implemented in the DAUNTLESS In-Ear Monitors. It features an intricate network of acoustic pathways that is integrated into the 3D-printed (3DP) shell structure and the utilisation of a balancer tube for pressure control. ZEPHYR takes full advantage of the PBAS system to significantly enhance the overall sound qualities of the drivers. 

It’s honestly a lot of technical talk, but the only thing you need to know is that the way they designed the acoustics of the Zephyr allows it to be tuned exactly how Kotori Audio wants while also ensuring that the air pressure build up is completely eliminated. 

And boy, did they eliminate the air pressure build up. One of my biggest  comments about the Kotori Vampire is that the air pressure build up genuinely affected my enjoyment of the IEM. It’s a unique and interesting IEM to listen to, but the air pressure build up forces me to listen to it in a static environment with minimal movement so as to minimize the changes in pressure in my ears. The Zephyr completely negates that thanks to their PBAS system and I am so for it. This also allows for such a fine level of tuning on the IEM, which we’ll talk more about later.

But let’s go out to the faceplate and shell, starting with the faceplate. 

They utilized modern and traditional techniques with a “Bauhaus-inspired” design language that represents the spirit of the wind god, Zephyrus (which it was named after). Elegance is the name of the game for the Zephyr and, well, it’s quite elegant. Maybe a little too elegant. 

On first look, I found the Zephyr’s design to be a little odd. The hexagonal protrusion sticks out quite literally with elegant waves descending down to the shell. Maybe I’m just used to more extravagant or eloquent designs, but I initially found the Zephyr’s design a little dull. But the more I observed it, the more I realized how much thought was put into the design of this thing. It’s not a hexagon placed on top of a shell, each corner connects gracefully to the lacquered resin shell. Plus, the CNC aluminum shell is a nice touch to give it a premium feel.

As for comfort, I can already tell you that this will completely depend on your ear anatomy. While that is the case almost 90% of the time, I can assure you that the Zephyr is probably the most tip and ear dependent IEM that I’ve reviewed recently. This is due to the very aggressive inner shell and wing structure that allows it to dig into your inner ear for stability, but also add discomfort for those who don’t have the same ear anatomy as their mold. Thankfully, they molded the Zephyr for my ear (this is a joke) because it fits like a damn glove. Granted, you NEED to tip roll with these as the stock tips are unfortunately not enough for me. The texture and shape just feels like it couldn’t go in too deep without causing issues.

However, long listening sessions prove to be a little fatiguing as the wings dig into your inner ear. I don’t hate the long term fit as stability is probably one of the best for the price, but it’s done to the extreme where it might cause problems for anyone with a different earshape. And then of course the lack of air pressure builds up, but I’ve already made a section about that. 

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As for the cable, it uses the same Carbon 3 cable that was used on the Vampire which is apparently an upgrade from the Carbon (2020. I don’t have that cable to compare, but I do have the Carbon 3. And the Carbon 3 is a pretty good cable! It’s not fancy braided 8 core gold plated nonsense, but it’s a functional, aesthetically pleasing and comfortable cable with a very bulky but pretty looking chin cinch and y-split and an L plug. I will always put L-plugs above straight plugs for the sole reason that they just feel more durable due to the fact that they have less jack length to snap or break. But that’s just me. 

Here’s a message from the designers:

SOUND

Sound Signature

Arguably the thing that makes the Zephyr stand out from not only Kotori Audio’s own catalogue but also IEMs in the price is its almost deadpan neutral tuning with a bit of spice in the top end. The bass to midrange is one of the most neutral I’ve heard under $200 with the treble providing a decent level of detail and clarity at the cost of timbre. We’ll talk more about that later. 

Source Pairing

Don’t let that 92db of sensitivity fool you. Well, maybe a little bit because compared to something like the KZ PRX with a similar level of sensitivity, the Zephyr is one that doesn’t need much power to drive properly. However, the Zephyr is similar to the PRX with how sensitive it is to sources. Pair this with a bad source and it’ll screech at you. But pair this with a good source and you’ll hear angels fly. I personally enjoyed pairing this with the ever-so-reliable Fosi SK02 and the HiBy R6 III. I’d probably pair a straight up warm source with this, but I think that’d ruin the tonality a bit much if the lower mids gets colored any more

Volume

I found myself not going beyond mid volume due to the peak at around 4-5k that is a clear violation to my HRTF. But in mid to low listening volume, this thing is a beaut. 

Bass:

The bass of the Zephyr is on par with the Dunu Kima 2 in terms of tonality. This means that the Zephyr has one of the flattest, most neutral but cleanest sounding bass you can find under $200. Seriously, how Kotori Audio was able to achieve this is beyond me or their PBAS system. It’s so clean and soothing and perfectly compliments the midrange. I found myself enjoying jazz, instrumental and orchestral tracks the most here, so expect me to mention those in the songs section. But it’s genuinely impressive how well-tuned the bass of the Zephyr is. However, it does have an achilles heel. This level of control in the tuning lead to a rather nasty con for me personally. Tactility. Now I’m not gonna complain too much as this is a $150 with a relatively neutral bass tuning. I don’t expect anything in this price point to have a tactile bass presentation, but it falls a little too smooth and too clean to the point where I genuinely feel like they focused too much on getting the tuning right that it got over smoothened. It’s not the worst I’ve heard and totally appropriate for the tuning, but I also know that this is the limitation of the price and not necessarily a con for them. Bigger bass IEMs have the quantity to mask this, but IEMs like the Zephyr unfortunately have to live with the fact. 

Listening to a track like Diving In on the Sky: COTL official souindtrack by Vincent Diamante shows the level of maturity that the bass of the Zephyr has. Tight, smooth and present when the track calls for it. During the forte moments of the track, you really feel the air and string instruments come together in such a beautiful, deep and lush harmony unlike anything you’ll hear with IEMs with a subbass focus. The beauty of IEMs with a linear but slightly warmer bass tuning is that you get the weight while maintaining detail and clarity of the notes, and the Zephyr is one such IEM that does this

Mids: 

The Midrange presentation of the Zephyr is two fold. One with vocals and one without vocals. Without vocals, this thing is absolutely amazing. The level of nuance and detail featured in the midrange of the Zephyr is second to none compared to other IEMs in this price range. It doesn’t aim to compliment the bass or the treble, instead it lives in its own little bubble where you get to hear every single detail with such finesse and crispness. It’s a lovely midrange for instrumental tracks and orchestral tracks and has been my go to for those genres. From pianos to Kenny G’s famous saxophone, you get a level of detail and crispness unlike any other IEM in the price. 

Unfortunately, once the vocals start to pop out, it gets a little indecisive. The lower to midrange presentation is immaculate. Male vocals tend to sound good most of the time with the lower frequencies sounding quite cohesive and rich. But once you breach the upper midrange to where the female vocals are, you start to feel like something is wrong. Is it the overly vibrant upper mids to mid treble? Is it the contrast from the calm and collected lower frequency to the energetic treble? Whatever it is, there’s a sudden shift in energy that may seem quite odd at first listen. However, I’ve slowly grown to love this kind of sound for the reason that it focuses that energy where instrumental tracks shine. 

I absolutely loved listening to Kenny G’s tracks on the Zephyr. From his older Breathless album to the New Standards, his sax just never gets old on the Zephyr. The placement of the energy is just perfect as it never sounds fatiguing, yet the details and clarity is phenomenal. I absolutely adored his music again when I listened to him on the Zephyr, and that’s saying something. However, the same cannot be said for tracks with already bright vocals such as You Should Head North by Necry Talkie. S and T sounds just gets so unbearably sharp that it somewhat ruins the tonality of the music by quite a bit on first listen, but starts to normalize after a while.

Treble:

Now to the part that completes the beauty that is the Zephyr. The treble is peculiar in a couple of ways. While the lower frequencies to midrange frequencies are smooth and calm, the Zephyr takes a step up in the treble and provides a very crisp, detailed and borderline analytical sound that is almost treblehead level if you like mid treble. The kind of treble that the Zephyr has isn’t the airy kind, but the sharp and snappy kind. There’s a good amount of air, yes, but most of the energy is pushed to the mid treble from 4k all the way to 8k with a bit of edginess and roughness. I’d be lying if I told you that the weakest aspect of the Zephyr to me is the treble. Unfortunately, this energy does more harm than good for the overall presentation of the sound as the smoothness of the lower frequencies contrasted with the sudden peak in the treble doesn’t sound cohesive. This also suffers from bright or poorly mixed tracks that do NOT hide the flaws of the mix whatsoever. Some people like that, but I know that some people might come to this expecting a smooth and lush experience. Unfortunately, it isn’t

I can name a hundred songs that I found to be problematic due to the treble of the Zephyr, but I’d have to give it to Toto’s IV album in its entirety. Such a brightly mixed album with heavy emphasis on percussive instruments in the treble that end up sounding scratchy and metallic 90% of the time. However, orchestral tracks with tamer and mature mixing like the aforementioned Vincent Diamante collection of Sky COTL albums as the mixing is smoother and more generous compared to Toto’s IV. You can also throw in Samara Joy here as the mixing of her albums is honestly second to none with how clean yet detailed it is. Despite the hardest attempt of Zephyr to expose the mixing of linger while, that album is just mixed too well. 

Technicalities:

For $150, the Zephyr provides a surprisingly competent level of technicalities, especially in the separation and layering section. While it’s not the most defined sounding IEM for the price, the way that it handles complex tracks is pretty impressive with instruments being placed with a good level of separation from each other. Headstage is decent in terms of height, but generally puts vocals in your face and the rest in the background thanks to its tuning. Imaging is also quite impressive considering the up-front tuning of the Zephyr, but I’d probably attribute that to the impressive separation and layering. Unfortunately, the weakest technical aspect of the Zephyr is dynamics and resolution. It’s not the most dynamic or resolving IEM for $150, which I kind of expected with my previous experience with the Vampire which only had a single BA. $150 is a little steep for an IEM with this level of resolution and dynamics, but I’d argue that the tuning alone makes it worth getting.

COMPARISONS

vs KZ AS24 Pro

The AS24 is a set that I fell in love with due to its DF-like tuning that stands out not only amongst KZ IEMs but IEMs in its price range. This comes at the cost of a rather nasty dynamic compression as the balanced armatures they used sound a little limp compared to their dynamic drivers. Regardless, its tuning reminded me a lot of the Zephyr in many ways with the main difference being the Zephyr’s somewhat edgier treble but more neutral midrange. The emphasis on the upper midrange for the AS24 Pro is something that some people might love but others hate. The Zephyr in comparison is tamer in that region, but edgier around the mid treble around the 4-5k region. Technically, they’re not far off which is not a good thing considering they’re above $100 and there have been many sets with impeccable technical performance for much cheaper.

vs CCA Hydro

The Hydro is a more traditionally v-shaped IEM which contrasts the neutral bright tuning of the Zephyr. In a way, it’s the perfect contrast to the previously compared AS24 Pro with its more emphasized treble and bass that makes it a more engaging and fun sounding set overall. This makes the Zephyr a more “reference” and “neutral” set, but the mid treble sticks out like a sore thumb compared to the Hydro’s consistent treble presentation.

vs Dunu Kima 2

From one reference set to another, the Kima 2 has a more natural overall tonality with the timbre being more consistent. The dynamic presentation of the Kima 2 is also considerably better, in exchange for sounding a little bit stale compared to the more nuanced Zephyr. The cost of being neutral is sounding a little dead which is the case for the Kima 2, while the Zephyr’s more distinctly bright tuning is something that not a lot of IEMs can do without having a massive con. The Zephyr nearly reached that con, but just stayed within the borders of whats acceptable. The Zephyr is a more revealing but less consistent sounding IEM compared to the Kima 2’s more linear but consistent tone

vs Celest Phoenixcall

A set that reminded me a lot of the way the Zephyr did coherency was Phoenixcall. The Phoenixcall was the OG Tribrid-sounding Tribrid in the budget-ish segment that really leaned into the Tribrid sound. However, this is something that might end up being a con for those who like a more consistent sound. Regardless, the Phoenixcall completely contrasts the Zephyr in terms of tuning while having a similar level of emphasis on specific areas of the frequency. Technically, the Phoenixcall is still more impressive but the tuning of the Zephyr is just a little bit more neutral to my tastes.

vs EPZ K1

Another 1DD+1BA hybrid, but much lower in the price range. The most distinct difference between them is the emphasis on the bass and warmth for the K1 while neutrality reigns on the Zephyr. It falls under preference more than objective improvement, but the K1 definitely sounds more versatile than the Zephyr’s more selective genre options as the low end is considerably flatter. However, this also makes the Zephyr an overall better “reference” set over the K1’s more vibrant and engaging tone

vs Etymotic ER3SE

The ER3SE is arguably the best comparison I can make with the Zephyr due to their very similar DF-style tuning. The difference? That upper midrange that makes the ER3SE a proper semi-DF IEM while the Zephyr tries to balance it out by giving it a bit more low end and pushes emphasis around the 4-5k region. But I would choose the Zephyr any day thanks to the considerably more comfortable overall fit compared to the ER3SE. The ER3SE might have a superior coherency and smoothness, but not when my ears bleed because of the fit (yes, my ears have actually bled because of Etymotics)

CONCLUSION:

Despite its flaws, the Zephyr is a unique and compelling IEM from a brand with only 3 IEMs under their belt. Their efforts proved to not be in vain as the Zephyr provides such a distinct listening experience under $200 for those who are brave to try sets from a boutique brand that won’t just waste away in your drawer. 

However, this doesn’t mean that the Zephyr is free from my critiques. From the lack of texture to the odd peak in the treble, I think Kotori has a long way to go to get their products in the mouths of of the mainstream. If I were to comment on specific things I’d like to be changed, I’d love for the treble energy to be moved down to maybe the upper midrange and tame the mid treble further as I’d take shout over a 4-5k treble peak any day. This is what makes Etymotic IEMs stand out after decades and if Kotori can create an IEm with the Zephyr’s low to midrange with a heavier emphasis on the upper mids and less in the lower treble, then I genuinely think that it could comfortably compete with sub $200 IEMs. Maybe also improve the quality of the bass, but that’ll require a bump in price which I’d argue is a worthwhile investment.

Regardless, Kotori has been steadily improving their products in every release. I have complete respect for their company because I can see their desire to improve and create a great product stems from their foundation and not to just make a quick buck with OEM parts. They really think about the quality of their products and pour an audiophile’s love into their products. And for that, I think Kotori is a brand to look forward to and the Zephyr a set to consider for those who want a unique neutral-bright sounding IEM from a boutique brand that shows their care for their customer.

Thank you for reading my review on the Kotori Zephyr, If you would like to order one, consider using the non-affiliated link below. https://kotoriaudio.com/products/zephyr-iem