Cayin YB04

General Information

  • Knowles/Sonion BA Combination
  • CNC Aluminum Enclosure
  • 8-wire Unidirectional Crystalized OFC x Silver Alloy cable
  • High Quality 3.5mm Gold Plated Connector
  • Hexagon Design Aluminum Spliiter
  • Gold-plated 0.78mm 2-pin Connectors



Latest reviews


Reviewer at Headphonesty
Cayin YB04 – Soothing the Serrated Soul
Pros: -Attractive packaging
-Complete accessory set
-Premium cable included
-Robust build quality
-Comfortable fit
-Very good isolation
-Accurate tone and timbre
-Captivating mids tuning in patches
-Airy, detailed treble
-Extra wide soundstage
Cons: -Utilitarian design not for everyone
-Heavy shells
-Contrasting, incoherent signature
-Performs well in selected genres
-Poor bass technicalities
-Uneven mids response
-Feather-thin treble
We go old-school cool with one of Hi-Fi’s traditional brands, Cayin. Performing on a new stage, the YB04 is their first-ever earphone, a four-driver with a captivating and enchanting tuning.

In the past, I have alluded a few times that my dad was the true-blue Hi-Fi enthusiast, with multiple 2-channel speaker sets and all; while I am the impostor of the house still dabbling with portable audio. While he bossed around with old-school big brands like Marantz, Nakamichi and Harman/Kardon, I got my kicks from… Moondrop?

So it is with great pride and pleasure that I get to review a product from a big name in the world of Hi-Fi, Cayin. Formed in 1993, for as long as I remember they’ve been associated with CD players and sweet-sounding tube amplifiers. But since 2013, they’ve made quite a push into portable audio, making splashes with their digital audio players (DAPs), notably the N8 and the alien-looking N6.


Today we take a look at their inaugural foray into in-ear monitors (IEMs), the YB04. It is a 4-balanced armature (BA) IEM consisting of 2 Knowles tweeters and 2 Sonion woofers per side, enclosed in a machined CNC aluminium housing. Addressing the elephant in the room, there aren’t any dedicated drivers for delivery of mids, but in its place is a carefully-tuned crossover design that covers the whole audio spectrum.

The YB04 looks like an engineering delight, but what Cayin is more proud of showing you is probably the sound. Their house sound is known to be smooth, velvety and analogue-sounding, with musicality and euphony at the forefront. Their vision of the perfect sound is hopefully captured in its glory here.

The YB04 is available via Cayin or Amazon. I would like to thank Mr. Andy Kong of Cayin for providing the review sample and making the review possible.

This review was originally published in Headphonesty.

Equipment Used

  1. FiiO M15
  1. Cayin YB04
  2. Fearless Audio S8 Freedom
  3. FiiO FH7
  1. Amber Rubarth – Sessions from the 17th Ward
  2. Art Pepper + Eleven – Modern Jazz Classics
  3. Dua Lipa – Future Nostalgia
  4. Fleetwood Mac – Tango In The Night
  5. Macy Gray – Stripped
  6. Melissa Menago – Little Crimes
  7. Prince – Musicology
  8. Simon and Garfunkel – The Essential
  9. The Weeknd – After Hours
  10. The Eagles – Hell Freezes Over
Technical Specifications
  • Enclosure: Machined CNC Aviation Aluminium Alloy
  • Driver: 4 Balanced Armature Drivers (2 Sonion Woofers, 2 Knowles Tweeters)
  • Frequency Response: 18Hz – 40kHz
  • Impedance: 30Ω
  • Sensitivity: 113dB @ 1kHz ±2dB
  • Cable Length: 1.3m
  • Cable Material: Unidirectional Crystalized OFC and Silver Alloy
  • Plug: 3.5mm TRS Single-ended
  • Connector: 2-pin 0.78mm

Leather, whip, a clamp, and a selection of plugs. Right.

Packaging and Accessories
I wasn’t expecting a shoebox. But then again, sometimes I order lunch and don’t get what’s on the picture, so we have to embrace life’s curveballs. The YB04 is extravagantly packed, much like FiiO’s over-the-top packaging, but in our industry, this is a good thing. A cardboard sleeve with the IEMs prominently displayed in front, covers a thick, magnetic cardboard box with layers of protective foam inserts.

Open the magnetic clasp and there, like two crown jewels pulling your utmost attention, lay the YB04. It’s a dramatic unboxing befitting a showman. But we’re just getting started. The YB04 comes bundled with a full, unrestrained accessory set that completes the premium experience. Included are:
  • 3 pairs of “bass” silicone ear tips in S, M and L sizes
  • 3 pairs of “balanced” silicone ear tips in S, M and L sizes
  • 3 pairs of “vocal” silicone ear tips in S, M and L sizes
  • 2 pairs of foam ear tips in M size
  • 1 pair of double-flanged silicone ear tips in M size
  • Leather carry case
  • 1.3m 8-wire unidirectional crystalized OFC and silver alloy cable
  • User manual
  • Cable clip
  • Cleaning brush
The sheer number of ear tips allow you to customize the fit and sound profile that suits you best. The leather case is roomy and robust, and looks exquisitely made. I love the cable too, which I’ll touch more on later. Make no mistake, at $499 the YB04 is a tad expensive for what it offers, but the accessory package goes some way to convince you that this is a luxury item from the get-go.

Design and Build Quality
I understand that for marketing purposes, “carved from a single block of something” sounds awesome-sauce, but drives up costs. So Cayin came up with the next best thing, using precisely-machined CNC aluminium to combine the faceplate, outer shell, inner shell and nozzle into a smooth, seamless structure. The earpiece is held together by three Andromeda-like screws.

Aesthetically, the YB04 is a handsome stud. This is subjective of course. The polygonal faceplate, polished inner surface and titanium/copper color choice possesses an industrial charm, simple and not overdone. Just looking at it you already know not to pick a fight with it. Here, form serves function, and the YB04’s design highlights its robust and solid build.


The screw placement makes the YB04 look like a confused lil’ dude.

Like wine pairing with your main course, Cayin takes its cables seriously. Eschewing the tried-and-tested Plastics One route most companies would take, Cayin built a cable from scratch to optimize synergy with the YB04. This 8-wire, two-toned hybrid cable has 4 wires of unidirectional crystalized oxygen-free copper (OFC) and 4 wires of silver alloy, which underwent annealing and recrystallization processes to maximize purity and conductivity.

The custom-made aluminium Y-split and 3.5mm jack share a distinctive hexagonal barrel, with colors matching the YB04 housings. The 2-pin connectors have a non-recessed extruded design, providing some protection to the fragile pins so they won’t snap off during a cable-swapping fever. This is a well-designed and well-crafted cable that looks absolutely resplendent.

The cable is a joy to handle as well. Despite its 8 wires, the cable is thin, soft and lightweight, and easily conforms to coiling and uncoiling. The braids are tight and weaved beautifully throughout. When left on its own, the cable has very little memory effect and kinking, assuming its intended shape without much effort. Top marks for ergonomics.


Too early in the year to be thinking of Santa’s sleigh.

Fit, Isolation, and Comfort
An all-metal earpiece might look sharp, but will always have a weight barrier to overcome, compared to conventional plastic or resin IEMs. The YB04, with its aluminium housings is heavy, and needs the ear guides from the cable to help shoulder some of its weight, as well as a good deal of support from the nozzle and ear tips. This knight in shining armor is high maintenance.

Once properly fitted, the smooth inner surface of the earpieces confer excellent comfort. The shape and inner curvature is, after all, designed based on extensive research of listeners’ ear structures. You will never say the IEMs feel weightless, but the sensation of smooth, polished metal caressing the insides of your ears is, at least, a comforting thought.

Isolation is excellent once the seal is good enough. Up to 80% of environmental noise is put aside given the right ear tips. A full-BA design will always have an edge over dynamic driver and hybrid IEMs because there is no need for vents. This happily leads to quieter surroundings and a more intimate listening session. Just you and the music, wherever you go. Mind the traffic.


The YB04 would like to tell you something about his orientation.

Sound Quality
You’ve heard terms like house sound, analogue and musical bandied about to describe the Cayin sound, but do they cut the mustard? Let’s find out.

Overall Sound Signature
If we just scratch the surface, the YB04 possesses a neutral signature, with a slight emphasis in the mids. Listening closer, there are layers to be uncovered. Firstly there is warmth, especially in the bass and mids, as the notes tend to be full-bodied and rounded at the lower end. Contrastingly, there is brightness and coldness as we ascend from the upper mids to the treble.

The sound seems to be a direct effect of the dual-woofer, dual tweeter driver configuration. Anchoring the distinct two ends, are mids that are emotive, resonant, and captivating, but only when done right. This is a unique tuning that Cayin hopes to, in their own words, “put you there in person”. The YB04 tries to accomplish a great many things, almost with a split personality.

It marries natural, timbral accuracy with emphasized detail and transparency. Note character alternates from thick and luscious to thin and raspy. The presentation is quite relaxed and spread out across a magnificent soundstage that awes and inspires. The end result is, to say the least, unique. A sound that soars and sinks, but with no limits to its courage.

Listening Conditions
Critical listening was performed after 50 hours of burn-in. All that metal would need some high heat sear to reach its fullest potential, and boy do I have some Tefal at home. Burn-in did not bring about any significant changes in sound, but the YB04 smells heavenly. The main review rig is FiiO’s M15 DAP, using the stock cable and “balanced” silicone ear tips.


“Tell me your problems,” said the Cayin, “I’m all ears.”

I lived in an era where the only drinks available in McDonald’s were fizzy drinks and thick milkshakes. YB04’s bass would be the milkshake stand all day and night. The primary focus is in the midbass, slightly elevated with a thick, smooth and rounded texture. It has a lovely, natural tone and is the main provider of warmth for YB04’s signature.

While there is nothing to fault about the tone, its technical ability leaves much to be desired. Extension to the sub-bass is average at best, just audible but lacking the physicality and guttural response that the best bass drivers provide. The midbass, while rich and velvety lacks punch and slam. Notes are less well-defined, indicating a lacklustre resolution.

Making things worse is the sluggish decay, so there is some smearing in fast passages. Notes are fuzzy and struggle to stand out on their own. And when that happens, a lack of dynamics and snappiness ensue, two criteria I value highly in bass. I have no doubt it sounds lovely in slow to mid-tempo genres with simple arrangements, but anything besides that I’m not too sure.

Too much love will kill you, said Brian May. I’d say bankrupt, but still. And so the outpouring of love from the bass spills over to the mids. The upper bass to lower mids transition isn’t clean, resulting in some bleed and obscuring what is otherwise, again, an accomplished tone and timbre. Male vocals and bowed strings unfortunately take a step back when that happens.

Venturing upwards, the mids change in character, becoming increasingly detailed and airy as we approach the upper mids. Note body is lighter and more nimble. For once, music becomes crystal clear, spacious and well-layered. Female vocals and acoustic instruments are rendered lovingly, with a neutral and realistic tone cleverly balancing immaculate detail and tender smoothness.

If your music is vocal-focused and surrounded by simple arrangements, you can finally savor YB04 in its element, and it absolutely delights.

Ultimately though, YB04’s mids are uneven, alternating between the lush and smooth lower mids, and the airy and ethereal upper mids. YB04’s mids is frustrating in the sense that, when they get it right, it absolutely brims with emotion, and you’re transported to goosebump city. But when it doesn’t, your listening enjoyment is hampered by the jarring contrasts.


I’ll stay with you forever. Pinky promise.

Consumed by ecstasy only hinted at in the upper mids, the YB04 treble takes flight and never looks back. The entire treble region is transparent, spacious, and vivaciously detailed. The crispy and delicate note texture is easily felt and heard, as notes float in and out of the soundscape deliberately enjoying their freedom.

The treble is technically proficient too, showcasing excellent extension and a giddy amount of air up top. At its best the treble is carefree, enchanting and reminds you what it’s like to be young again. At its worst though, its playfulness can lead to trouble. Like the mids, it is peaky and occasionally tizzy. Hi-hats and cymbals can get hot in a hurry for instance.

Also, if compared to the rest of the spectrum, the treble sounds brittle and tinny, owing to the reduced note weight and relative thickness of the bass and lower mids. It can get too crispy for its own good. The lighter, speedier nature of the treble leaves listeners unsatiated, when an even-handed, smoother and matured approach might win more fans.

Soundstage and Imaging
The YB04 might have taken some hard knocks for its sound signature, but here is where they truly shine. Despite having ventless, fully-sealed units typical of a multi-BA IEM, they manage to sound open, and exquisitely wide. This is one of the widest soundstages I’ve heard in awhile, and the YB04 revels in it.

Depth and height are so-so, but you’ll be diverting your attention to the magnanimous width, and excellent left-to-right separation and imaging. Anything you have in your music collection that sounds stale or boring, or maybe a compilation of academic lectures, do give them a spin from the YB04 for a spin, just to appreciate the distance.


Catwalk-strutting lessons from the Fearless one himself.


Fearless Audio S8 Freedom

The Freedom is the jock of the IEM world, with a bold, aggressive and positively in-your-face V-shaped signature. Pitted next to the relaxed, demure-sounding YB04, Freedom is the loud-mouth who won’t shut up and in fact, will tell you where to stick your social distancing protocols.

Freedom has a fuller, rounder sub-bass that thumps and makes its presence known. The midbass is punchier and meatier too, while remaining better defined than the YB04. This is a fight the Cayin isn’t prepared for. In mids, Freedom sounds bright and grainy next to the natural and accurate YB04, although shining admirably in speed and transient response.

The treble is where I have the most beef with Freedom. It is aggressive, peaky and borderline sibilant, negating whatever technical brilliance it possesses. The YB04 breezes through with a tamer, yet equally detailed treble. Freedom’s soundstage is small, sometimes to uncomfortable levels, although better in rendering imaging cues. Switching back to YB04 makes me appreciate how wonderful a spacious sound can be.

Taking all into consideration, Freedom has a signature that complements, rather than competes with the YB04. If you like clarity and excitement, take the former. If it’s euphony and calm you seek, by all means choose the Cayin.


Swanson, Burgundy… all the famous mustaches are named Ron.

FiiO FH7
Cayin and FiiO are on similar paths to portable audio dominion. FiiO started off with budget-only offerings, before taking it to the next level in recent years, culminating in their flagship hybrid, the FH7. The FH7 features FiiO’s version of a neutral, musical, people-pleasing sound. The comparison was done with the balanced, or neutral-est filter.

The FH7 makes headway in bass immediately. Boasting a beryllium-coated dynamic driver, the bass hits authoritatively, with impressive reach and slam. It’s heavy and satisfying, but cleans up after itself to prevent any bleed into the mids. The YB04 is inferior in extension, impact, layering and speed, sounding sludgy and bloated in comparison. The bass is all FiiO’s.

The YB04 ain’t taking this fight lying down, oh no, and comes roaring back with their brilliantly-tuned mids. Despite its own flaws, the Cayin sounds more accurate and realistic than the clarity-focused FH7, and runs circles around the FH7 in immersion factor. When Youn Sun Nah belts out her signature tune the FH7 makes you go “it’s aight” but YB04 brings tears.

The FH7 has a more solid and extended treble that borders on sibilance, and is the main polarizing factor of the renowned IEM. YB04 sounds thinner and tamer in comparison, although a bit too wispy and wafer-thin for comfort, like a waif-like supermodel in need of a Big Mac. YB04 wins the soundstage easily though, dwarfing the FH7 in size and scope.

Putting things in perspective, the FH7 is a better all-rounder, but YB04 is for the mids and vocal lover with an eye for the dainty.


Somebody get me a cinnamon roll.

Final Words
How do you build on a legacy? Cayin has its own firmly entrenched, as a company building quality tube amplifiers. That should last for a generation or two, but no. Cayin says there are kingdoms yet to conquer, and embarks on a journey to the hearts and minds of portable audio enthusiasts. The first wave was their renowned DAPs, and now the second wave begins with the YB04. Hold on to your wallets.

The YB04, while not perfect, has a bold statement to make. Its tuning is the direct antithesis to the all-too-common V-shaped tuning among its Chifi brethren. A lot of IEMs increase bass and treble levels to tease excitement, but YB04 taps into your emotional core by focusing on the delicate, beautiful and haunting mids, with rewards at each listen.
Last edited:
Hmm, very different thoughts than mine. I wonder if these are just different preferences, unit difference or problems with pairing with the source 🤔


Reviewer at Ear Fidelity
Cayin YB04
Pros: Perfect build quality
Great accessories
Fantastic looks
Neutral and natural tuning
Beautiful timbre
Cons: Comfort is just OK
Nothing more i can think about
Cayin YB04

Cayin YB04 is a first IEM by Cayin. It is priced at 499$ and has a lot to prove. Spoiler Alert : It does.

Sound quality
Rating: 9.5 out of 10.

Build quality
Rating: 10 out of 10.

Rating 10 out of 10.


YB04 impresses from the very first thing you’ll do, which is opening the box. Inside, you’ll find twelve pairs of eartips, the IEMs themselves, a 3,5mm terminated cable and a leather case.

The case is one of the best I’ve seen to date. Made of leather, magnetically closed, with lots of space inside and padded with soft material to ensure safety of our new in-ears. It can easily fit two pairs of IEMs, but hey, I don’t really recommend it, as they could scratch against each other.


The cable included in a box is a very pleasant suprise. It’s an 8-core, hybrid wire terminated in 3,5mm jack. On the other side, the cable plugs into the IEMs by 2-pin connectors, which work flawlessly and ensure that it won’t get disattached on it’s own.
Build quality

The build quality of Cayin YB04 is simply put – splendid.
The IEMs themselves are quite heavy, thanks to sporting a full metal body, but boy, oh boy, these things scream premium. Finish is excellent, all ridges and edges are perfectly made, and you’ll be far from cutting yourself.

Additionally, i adore the design and overall look of these. Those visible screws, big and chunky shells, beautiful texture makes me sing with delight. In terms of build quality and accessories, i haven’t seen a debut that good…well, ever. Chapeau Bas.

YB04’s comfort reminds me a bit of a “pink elephant”. You see these big and heavy shells and you assume, that these won’t be too comfortable. Well, youre kinda right, and kinda wrong. They are not a very comfortable pair of IEMs, but they aren’t uncomfortable. See what i mean? These are nowhere close to the level of Fiio FA9 or any custom in-ear, but at the same time they’re not fatiguing like Campfire Solaris or Sony IER-Z1R. Comfort of the YB04 is decent, its okay, and for the shells that big and chunky, im actually pleasantly suprised.

These beauties sing thanks to four balanced armature drivers, from which two are the Knowles tweeters, and two are the Sonion woofers. I personally adore Sonion drivers being responsible for the low frequencies, as im yet to find an IEM that has a bad bass/lower mid using these.

If you’ve survived to this part you’d already know that in my opinion Cayin made a spectacular debut to the IEM market regarding the build quality, accessories and just an overall design. But all that would have been for nothing, if the sound ended up being poor. Well…

I could describe YB04 in two words, which are : Neutral, natural. But hey, that’s not it, lets dig a bit more into it.
I said that im yet to find a bad sounding bass on a IEM using Sonion driver. Yes, im in for a longer wait then. The bass in YB04 is fast, resolving and greatly extended. I’d say that it is very mature and it sound’s just like it should in some way.
It’s performance varies on the music you’re gonna listen to, but it’s always pretty true to world. When it has to be punchy and bloated, it is. Not by a huge margin, but it has this slam and it tends to make your head bob.
But at the other hand, when talking about bass guitars or a contrabass, it pronounces every single touch of the string with great class and sophistication. Actually, it reminds me a bit of Campfire Andromeda, but is definitely less bassy in the overall quantity.

The midrange is colorful, analog and just beautiful. It has a very natural timbre to my ears, vocals and natural instruments sound just like it should, without even a slightest sharpness or overexposure. Mid’s are quite calm and lush, doesn’t sound aggressive or overly forward. The closest resemblance for midrange in the IEM market i can mention is definitely Meze Rai Penta. Meze has this lovely timbre, sounds just very pleasant and rich. I find YB04 to be quite similiar in this regard.
The Treble is very neutral to my ears. No spikes, no harshness, sybilances. But also, it’s not shy, dark or veiled, hell no. Imagine the Campfire IO, with this slightly sweet, but yet pronounced and saturated high frequencies, and you’ll get what i mean. Great detail retrieval, cymbals sound thick but edgy at the same time. Keep in mind, that pairing these with an overly bright and sharp source MIGHT end up with a very forward and sharp treble response. Plug these into the Cayin N6ii or a Sony WM1A and you’ll be blown away.

As for the soundstage, it is very good, but it ain’t anything crazy. I mean, the imaging is spot on, airiness and separation is quite pronounced and the overall size of the stage is natural. Yet, Rai Penta offers a quieter background noise, which result in a more convincing and spectacular effect of music coming out of a complete darkness. Anyhow, these have great soundstage – its tidy, airy and images well.

Im still suprised how marvelously Cayin has stepped into the IEM game. Pricing your first model at 499$ could be a risky game, but i believe it was a great choice.

Perfect build quality, fantastic accessories (that case!), beautiful, industrial design and a very competitive sound quality with a lovely, yet safe timbre. Cayin YB04 has it all to be called the best IEM for the price. I believe that soundwisely this is what the Fiio FA9 wanted to be, but they fall short in comparison. I already can’t wait for the next IEM by Cayin, but till then…YB04 are HIGHLY recommended.

Gear used during this review for the sake of comparison and as an accompanying equipment:
  • IEM – Lime Ears Aether R, Lime Ears Pneuma, Campfire Audio IO, Andromeda, Solaris, Fiio FH3, Fiio FH5, Fiio FH7, Meze Rai Penta,
  • Source – Smartphone, Cayin N5ii, Fiio M11, Fiio M15, Cayin N8, Shanling M5s, Sony ZX300, Sony WM1A, Shanling M6.

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500+ Head-Fier
Pros: Impeccable build
- Resolving treble
- Good micro-detail retrieval
- Not too picky with sources/very easy to drive
Cons: Stock cable has annoying memory hooks
- Heavy housings
- Bass extension is lacking
- Upper-Midrange can get shouty/harsh on high volume
Cayin YB04 Review
Opening Shot


Judging the “first ever” product in a brand’s lineup is quite perplexing.

There’s no precedence, so it has nothing to live up to (in a sense). Mostly there isn’t much expectation; it’s new, so you just don’t know what might come out of it. On the flip-side, if it’s a turd — that’s the end of said product line for the most part, and the company has to either bury the very existence of it (Amazon Fire Phone, anyone?) or just deal with the stigma forever (Microsoft Kin, darn).

Cayin’s first ever IEM, the YB04, faces that particular dilemma. If it’s too safe/bland in terms of tuning, it might not stand out and be forgotten over time; or if it’s too unique, there might not be a successor at all.
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. Cayin was kind enough to send me the YB04 (courtesy of Andy Kong) as part of the review tour.

Sources used: Questyle QP1R, LG G7, Cayin N6 II, E1DA PowerDAC V2
Price, while reviewed: $400.

Having already reviewed the TOTL Cayin N6 II DAP, it’s time to check out how well they’ve nailed the IEM tuning test at the opening shot. Bullseye, or bust?


Build: Cayin usually gets the build quality right, and they’ve hit it out of the park again. These IEMs are incredibly well built, as good as anything out there. I’m glad that they chose an Aluminium alloy instead of the usual boring Resin shells as it just feels more premium in hand.

The IEMs have somewhat of an oblong pentagonal shape, which is rather striking when viewed in person. The backplate is removable (it uses the same Torx T5 screws as Cayin’s N6II players) and it seems like a great option to either DIY the shell with spray-paints/custom prints, or just make repairing the IEMs easier if such need ever arises. The raised geometric patterns on the backplate also give an industrial vibe to the overall design language.

Opening up the backplate you can see the internal wiring and the (plastic) driver chamber, along with the crossover circuitry. The driver chamber also consists of the wave-guides (to help with the cross-over issues such that phase incoherence etc.).
I couldn’t find any visible vent-hole in the IEM, though that’s likely not needed due to these using a BA-only schema (and the Sonion Woofers are not of the vented type). Naturally that leads to high noise isolation, provided you can get a good seal.

Then on the sides you can see the Cayin logo tastefully etched on the upper portion, while at the bottom there is the 2-pin connector (Cayin supplies a QDC-type connector here). The channel markings are right beside the nozzle along with color-coded dots beside the 2-pin connector. The nozzle has a steel mesh acting as wax-guard.

To summarize: impeccable build and finish, and wouldn’t feel out of place in a kilobuck IEM.


Accessories: Before getting into the accessories, I should probably talk about the box it comes in first. Man, Cayin knows how to make elaborate packaging. It’s great to look at and you feel like you’ve definitely bought something worth the price-tag. The IEMs are very well-protected with more than enough padding to likely survive a 10-story fall. Don’t test that claim, please.

Inside, you get the IEMs themselves nicely laid out with the wire already connected (I couldn’t take a shot of that since my review unit had the wires separated). Then there are the 12 pairs of eartips, 9 pairs of them sorted as Vocal, Balanced and Bass eartips (3 pairs each), a pair of dual-flange tips, and 2 pairs of foam tips. Unfortunately the stem of the Balanced tips (sonically best of them, to my tastes) were too stiff and caused pain in my inner-ears, so I decided to switch to Spinfit CP-500 which provided a similar sound without the comfort issues. Your mileage, of course, may vary.

Then you get the most exuberant leather case you will likely see in a while. It’s large, impractical if not impossible to carry in pant pockets and has a magnetic clasp. Yet, I adore it. I do wish the padding inside was softer. It should also have a cleaning cloth, a shirt-clip and a cleaning tool inside.

Finally, about the cable. This might be a contentious point but I’ll be frank — this cable is subpar in its build quality and overall usability. First, the good stuff — it’s lightweight, supple, the Y-split and 3.5mm connector jacks look awesome with their geometric shapes and subtle branding, and it’s not microphonic. This is where the good stuff ends though. That memory wire, for one, is beyond annoying. It’s stiff and unless you outright remove it with a knife — it’s there to make your life difficult. Then comes the strain reliefs. The Y-split only has a bottom strain-relief (you also need one at the top for obvious reasons) while the relief on the 3.5mm jack is too stiff to be of any use. As a result, you may find that the braiding of the wire around the jack has come loose.

So yes, while the case is great, it’s not too practical to carry around. The eartip selection is good, but the stem is very stiff on the preferred Balanced tips. The cable looks good upon first glance, then you try to wear the IEMs battling the memory wires. The fancy points are scored at the expense of usability and practicality, and that’s a bummer.


Comfort: The YB-04 is heavy, and has a short-ish nozzle that’s also quite thick. The end result is obviously something less than ideal. It’s not an IEM you put on and then forget about. The stock cable with it’s horrible memory wires don’t help as well, so I often had to take a break every 30 mins or so. Swapping to a better cable helped, but didn’t make them as comfortable as, say, Meze Rai Penta. I also found out that they are not suitable for listening while lying down as the weight tends to loosen up the seal.

Now, onto the sound. This is a quad-Balanced Armature setup, with dual Sonion woofers (33AJ007i sealed variant most likely) and dual Knowles SWFK-31736 as the mid-to-high drivers. The crossover setup is a two-way crossover. The sound impressions below were mostly formed with the CP-500 or stock Balanced tips, and Cayin N6ii as the source (since Cayin advertises them to mesh well).

Lows: Cayin aims for a balanced low-end presentation with these, which obviously means a total lack of sub-bass rumble and a mid-bass that’s mostly there for immediate impact rather than substantial body/slam/whatever you may want to call it. Snare hits lack body, and if you’re a drum track aficionado this might not be the most ideal pair for you.

On the plus side, there’s no mid-bass bleed into the lower mids, so — hurrah? Moreover, the bass speed is fast with the typical unnaturally fast bass decay, which if you prefer the nimbleness of BA bass will be right up your alley.

Overall, there is not much to see here for those who prefer south of neutral bass, let alone the bass-heads. It’s a conscious tuning decision and as such might be the deal breaker/maker for you depending on your preferences.

Mid-range is in the front and center of the YB04’s tuning philosophy, and as such should be the most critically judged aspect of the signature. First up, the overall frequency response. The rise from the lower mids to the upper mids is smooth and very well executed. Thanks to the flat-ish bass response, mid-range doesn’t suffer from any bass-bleed, so you don’t suffer lower-mids congestion. However, due to the emphasis on the upper-mids, lower mids take a back seat for the most part and thus deep/baritone vocals sound distant, lacking the heft they should display.

Then comes the upper-mid tuning, and here I encounter some oddities. First up, it’s very apparent that Cayin is going in their own tuning direction rather than conforming to Harman 2019 or the DF target. Thus instead of the usual 3KHz pinna gain, we are met with a “sawtooth” upper-mid and lower-treble peak trio: one at 2KHz, one at 4KHz, and to wrap it up: one that 6KHz. The (un)holy trio if you are upper-mid and lower-treble sensitive.

Thankfully, it’s not so intense for the most part. While the ~8dB of extra boost in the upper mids and lower-treble regions might seem scary, they don’t sound as exaggerated in most tracks. This contrast between the upper and lower frequencies also aids somewhat in instrument separation with higher pitched vocals and string instruments being placed at the forefront.

Vocals have good texture, though the singers breathing in/out aren’t as natural as on certain other IEMs. String instruments sound especially sharp and will be right up your alley if you prefer a brighter string representation. Overall timbre is mostly natural though the upper-mids and lower-mids tend to be brighter in nature. Overall detail retrieval is excellent for the price-range and unless you are used to TOTL level of resolution — this should serve you really well.

All that being said, I’ve still encountered some harshness in upper-mids at high volumes, while certain tracks have a tendency to get sibilant (Lifehouse’s Somewhere in Between), or walk a fine line. It mostly happens in poorly mastered record, but certain well-recorded tracks also exhibit this. The YB04 can also be a bit intense if you are sensitive to 4-6KHz peaks so do keep that in mind.

This is the most favorite part of the YB04 for me. Cayin has tuned the treble masterfully and I can’t really find anything wrong with it. Cymbals crash with authority when needed, and then goes behind in the mix if the track is mastered as such. Violins sound smooth and the transition from one higher note to another is seamless. I do wish they put a bit more emphasis on the 8KHz, perhaps a linear fall instead of an abrupt dip, as it would’ve made cymbals strikes more prominent on certain metal tracks. But even in stock tuning I immensely enjoyed the cymbal strikes on Breaking Benjamin’s The Diary of Jane.

I do miss the shimmer and air that you get from some upper-tier IEMs with even better treble extension (e.g. Campfire Andromeda). Cayin has a small post-10KHz peak but then it rolls. At this point though, it’s basically nitpicking, and since the treble here can convey most of the details without messing with the FR too much — I am rather pleased.


Note: the following two sections may have varying perceptions for each individual due to a number of factors e.g. pyschoacoustics, insertion depth, ambient noise etc.

Soundstage: Soundstage width isn’t the best even when compared to some lower-tier IEMs, but the soundstage depth is really good. Loreena McKennitt’s Live rendition of Dante’s Prayer has an applaud section around the end of the performance, and it sounds plenty realistic on the YB04.

Imaging is fairly well-done, though I couldn’t quite get the 3D-holographic imaging I get on, say, the R2 Atens. The cardinal imaging (top/bottom left/right) were tad hazier and thus this didn’t seem to have the most accurate instrument placement.

Before I go on with this section, I should mention that for me ~$500 is the cut-off point for this bang-for-buck section. Anything more expensive will definitely sit on the diminishing returns spectrum. Since the YB04 is priced at $400, I will pit it against some higher-end stuff in the comparison section. I’ll just summarize it here: it can keep up pretty well in terms of mid-range resolution and vocal rendition even when pitted against higher tier stuff. Where it falls short: bass, treble extension, and soundstage/imaging. However, I’m still not amused with that cable and the stock tips so I need to consider people having to replace them.


Source and Amping: While the YB04 doesn’t need much power to run (most dongles and phones will get you to sufficient volume), it will pair better with slightly warm sounding source rather than the analytical ones. My LG G7 for example made the mid-range more shouty, while the QP1R and Cayin’s own N6ii tamed that into a more enjoyable presentation. A low output impedance is mandatory as well due to its BA-only design (higher output impedance sources will skew the frequency response).

Select Comparisons

Fiio FH7: The Fiio FH7 is, for now, the flagship of Fiio’s IEM lineup and has garnered quite a following. It is a five-driver hybrid, with 4 BA drivers taking care of the mids and highs while a large 13.6mm Beryllium coated dynamic driver is tasked with low-end/bass duties. Being priced similar to the YB04 at $450, this will make for a very interesting comparison indeed.
Both IEMs are incredibly well built, and both come with plethora of accessories though I’m more partial to the Fiio accessories pack due to the inclusion of Spinfit tips along with switchable filters and a soft carry pouch. FH7 is also more comfortable thanks to a more ergonomic nozzle design and angle.
In terms of sound quality, the FH7 pulls ahead when the low-end kicks in. That dynamic driver is too hot to handle for the mere BA woofers on the YB04. However, YB04 immediately delivers a counter-attack with the midrange rendition that’s more upfront and less recessed than the FH7. Cayin also delivers better timbre to the midrange instruments, though both fall short of perfection. Treble is also more accentuated on the YB04 and can exhibit more apparent micro-detail retrieval, albeit this can be a bit too much for long-listening sessions. FH7 is less fatiguing in comparison but pushing the volume high can make the treble harsh and exhibit some grain. YB04 also has more upper-treble extension. Soundstage is similar while imaging is slightly better on the FH7.
As it stands, the bass response is what you need to consider if your choice is between these two. The midrange and treble differences are less stark, while comfort is indeed FH7’s forte.

vs Meze Rai Penta: The Rai Penta is Meze’s 5BA TOTL offering, and costs more than twice of the YB04 at ~$1000.
Rai Penta is definitely a looker, and the fit/finish is even better than the YB04. The shell is smoother with a more ergonomic shape and you can wear them for hours without the slightest bit of discomfort. The accessories are also of higher quality but given the price differential it’s expected.
When it comes to sound, they are polar opposite signatures. The Rai Penta is a mellow, laid-back listen while the YB04 focuses on detail retrieval across the board. Mid-bass is more boosted on the Rai Penta, and it’s followed by a midrange that’s mostly similar up until the upper mids where YB04 boosts 4K region further, and Meze takes a down-turn and mostly plays it safe along the rest of the frequencies. The tonality of the Rai Penta is more natural with less shout in the upper-mids, but the lack of treble energy can cause lack of dynamism in many heavier genres. Soundstage is wider on the YB04 while imaging is about similar.
Despite being priced half as much as the Rai Penta, the YB04 definitely comes ahead in terms of technicalities. These two IEMs are aimed at different audiences/genre however and they complement each other rather than compete.



Cayin has got a lot right with their first attempt at an IEM. It’s impeccably built, the price-tag is mostly competitive and they do somewhat achieve their target of an energetic, detailed signature.

The biggest room for improvement is in the bass department, as right now it’s lacking both impact and extension. Another potential improvement can be done in the mid-range to make it less peaky and have a smoother low-to-upper-mids transition. Treble response is mostly fine and apart from slight reduction in the 6KHz region and have a bit more upper-treble boost, there isn’t much I can complain about.

The shell isn’t ergonomic however and might be the biggest point of contention for potential users. The eartips and cable need some work as well. Availability is another issue as I couldn’t find them on Amazon whereas Fiio FH7 is there for a while. If Cayin can address these issues with the next iteration, we may as well have a default recommendation in the $500 range.

To summarize, the YB04 is a good option if you want something mid-centric that will retrieve gobs of detail without fatiguing you constantly.

Test tracks (as Tidal playlist):
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