Review: Cayin YB04 – Soothing the Serrated Soul

Cartman's subliminally convincing you to press the buy button, or else.
Cartman’s subliminally convincing you to press the buy button, or else.

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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.
Bottom Line

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.

What We Like 😍
  • 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
What We Don't Like 🤢
  • Utilitarian design not for everyone
  • Heavy shells
  • Contrasting, incoherent signature
  • Performs well in selected genres
  • Poor bass technicalities
  • Uneven mids response
  • Feather-thin treble

The Maiden Hour

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.

Where to Buy

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.

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.
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.
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.

A Twisty Tale

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.
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.

Apart of the Art

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.
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.

It’s Complicated

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.

Flood of Tears

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.
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.

Potato Chips

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.
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.

Mel Gibson Time

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.
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 Intimate Sibilant

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.
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.

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