Cayin YB04


1000+ Head-Fier
Pros: Incredible build, comfort and styling. Soft and very relaxing sound. Beautiful cable and prideful unboxing experience. Surplus of tips available.
Cons: Doesn't have bass slam nor treble "shine" that many may want.
*To me at least, the format isn't showing my full review (even the HIGHLY shortened and edited one I had to post here thanks to Head-Fi's new 10k character limit). I have posted my full, unedited, review on the Cayin YB-04 forum page here.*

*Yes, I'm sure you've noticed but I used the wrong form of through in my video cover. Didn't even realize I did it until obviously too late. Oh well. We'll have a laugh at it together.*
The Opening Experience


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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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Headphoneus Supremus
Pros: Reference yet very musical and engaging tuning, not analytical with seamless crossover
Outstanding clarity and transparency while remaining non fatiguing
Remarkable pitch black background, highly distinctive and key to the overall signature
Very wide and coherent soundstage with precise imaging
Timbre are spot on
Note attack and decay is very natural
Superb fit for a universal IEM
Cons: None that I can think of as long as you like a reference signature
The YB04 provided for the review Tour is a loan sample and has to be returned. No incentive was given for a favorable review. This review is my honest opinion of the YB04.

Listening notes
I spent approximately 50 hours with the YB04, listening to Cayin N6ii (A01 and T01 motherboard ) with Dunu Hulk cable using balanced 4.4 plug. I also listened out of the AAW Capri cable (with 24/96 DAC and mini balanced amp) plugged into the iPhone.

Special thanks
Thanks to Andy Kong for organizing the Tour and allowing me to be part of it.


The Cayin YB04 packaging is quite premium for a mid tier product, with a beautiful carrying case and a premium cable.



  • FR: 18Hz-40kHz
  • Impedance: 30 Ohm
  • Sensitivity: 113dB@1kHz
  • Enclosure: Machined CNC Aviation Aluminum Alloy
  • 2-pin and Single-ended (gold plated) 3.5mm termination, Unidirectional Crystalized OFC (30 core wire), Silver alloy (30 core wire) in the 8-wire cable

Fit, Build & Isolation
The YB04 build is flawless and the fit is superb for a universal. It looks sturdy, although I don’t know if the anodized paint is subject to scratch (I wouldn’t test this obviously). Isolation is good for a universal but as usual with aluminium, noisy environnement and lower listening level with let some exterior sound pass.


Cayin doesn’t really need to be introduced as it’s a brand that has built a great reputation in audio for over 20 years, venturing in personal audio only later in 2013. Lately, they’ve been on a roll with a stuning flagship DAP in the N8 (the first featuring Korg Nutubes) and the N6ii (a modular DAP with switchable DAC/amp). Continuing the recent trend, the YB04 is their first IEM.

On paper, a 4 BA IEM is rather uneventful in an era of trybrids and high count BA IEM. Still, when I had the opportunity to participate in a N6ii/T-01/YB04 Tour I couldn’t resist. Also, my experience is that tuning and implementation is just as important as any technical characteristics.

On the YB04 product page Cayin claim « Outstanding clarity and musicality across the frequency band » and states « We don’t emphasis or enhance, we only reproduce the original. We don’t offer appealing resolution, we just put you there in person ».

A very ambitious goal, let’s see if it holds its promises!


The very first minutes listening to the YB04 were sufficient to see that the tuning intent of clarity and musicality has been very elegantly achieved. It’s a very open sounding unit with a wide and tall soundstage, depth being only average.

The YB04 is all about balance between very strong technical foundations and a focus on musicality that doesn’t compromise its neutrality. This is harder to do than it appears and that’s why many IEMs that gave a shot at reference quickly ended up categorized as « boring », « dry » or « sterile ». The YB04 is anything but, as I found it highly engaging and lifelike in its presentation. We’ll dig deeper into this but I believe a lot of it has to do with a pitch black background.


The YB04 bass reflects its reference tuning : sub bass extension is fair but if you’re looking or physicality you’ll definitely be disappointed. The mid bass presence is just as balanced, it does convey rhythm but lacks punch and weight. On the flip side you’ll get a fast, controlled and detailed presentation that conveys a lot of nuance.

This is a general observation and since the YB04 is transparent to the source it can gain a bit of weight down low but don’t expect any kind of physicality. The YB04 will shine more on the subtleties of the double bass lower notes than the punch of percussive instruments. For this reason also you won’t get much coloration from the bass.

The YB04 mids are seamless in the sense that separation is very good but the soundstage layout is not spaced in a unnatural way, it’s very coherent and natural against a pitch black background. This and accurate tone and timbre plays a great part in making the YB04 mids quite lifelike and engaging.

Notes pop vividly against a black background, contributing to a very precise imaging, which is usually achieved with more separation and spread in the image layout. You get both a high degree of cohesiveness and separation, which is quite a challenge in my book.

Lower mids have just enough presence and warmth to grant the YB04 a natural tone, but it’s very contained and some might find male vocals lacking a bit of power. The YB04 is not thin but it’s not thick either and the mids have a featherlike touch more than a voluptuous body.

Overall vocal placement is slightly forward making for a clear vocal presence, and while I usually like my vocals with a touch of sweetness and warmth I found the crystal clear vocals were a treat on the YB04.

Upper mids are nicely executed, not too much emphasis and I had a hard time finding any hint of sibilance or harshness : the YB04 is a fatigue free IEM which given its clear and transparent signature was not a given on every recording. You can find yourself to the edge sometimes but it’s staying on the free side of the edge for me.

The YB04 treble is a good example of treble done right in my book, and a good indicator of the overall maturity that is found across the whole tuning. The product page says « We don’t offer appealing resolution, we just put you there in person ». The only thing I disagree with there is that the YB04 resolution is very appealing - just done in a way that isn’t relying artificially on boosted treble.

Again, the black background is key to make this happen : think about it this way, you won’t need to push the volume in a totally quiet room. For the same reason Cayin didn’t have to push the treble, against a black background the treble notes contrasts greatly and shine without over emphasis. I think Cayin has done a great job of infusing enough energy in the lower treble section to make the YB04 exciting, but it’s a subtle and savvy tuning that can send shiver down your spine when called for while never becoming fatiguing.

The upper treble section is seamless in the signature, it’s not the « in your face » technical upper treble presentation but rather the strong performer that shows restraint and stays within the goal of « We don’t emphasis or enhance, we only reproduce the original ».


As I mentionner earlier, I came into this review Tour not really expecting anything extraordinary with the YB04. I was curious how Cayin, a mature audio brand, would address their first IEM. There already was a hint with the product’s positioning, firmly in the mid tier price wise, but the hint was not a clue at what the YB04 can bring to the table.

You gathered it, I think the YB04 punches well above its price point and with some very distinctive qualities that sets it apart from the competition. It was a smart move to design an IEM with such an exceptionally black background (Black belt background ;P) that it doesn’t need to compete on the same basis as its competitors.

Cayin showed across the whole tuning it remained true to the product’s intent, a sign of maturity that is quite impressive for a first IEM. Some manufacturers would have come out and make a statement with a pure performance or an eager to please signature. With the YB04 Cayin chose to be the best at what it aimed to do : reproducing the original, put you there in person and for this, they chose to remove any distraction from the background, keep the goal of a reference yet engaging sound, and in its own understated way show masterful restraint that makes it such an elegant sounding IEM.

Quite a feat in my opinion, especially if you consider my own preference generally do lie in a thicker, warmer and more forward presentation. On top of this, my last review was such a special one as the FIBAE7 rocked me like nothing before it and the amount of time I spent with them before this review made me aware it would be a tough thing to review something afterwards. Call me impressed that the YB04 pulled me from my love affair and were able to shake me away from the F7 for a long bit! I am eager to see what kind of IEM range Cayin is going to build in the future… if this is mid tier, what would be a Cayin flagship IEM? I already have a big smile at the prospect!

If you’re looking for a natural sounding and engaging reference IEM, with an exceptionnally black background that allows its distinctively elegant tuning to shine, you’d be hard pressed to find a better candidate especially at this price point! If you’re looking for a reference tuning with stronger bass foundations, the pricier Penta might be a better candidate.


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Nice review. It would have been useful however to have a few comparisons, the passing comment about the Fibae 7 makes one just wonder...
Fair point. I’ll post comparisons later, just like source matching and cables... main comparison is to the Penta, the FIBAE7 are radically different tuning and on top of this a custom IEM.


Headphoneus Supremus
Pros: -Reference tuning with a touch of warmth in the mids
-SQ punches above its price
-Highs are well extended without being harsh
Cons: -Not enough bass for basshead but again this is a reference tuning IEM
Before I start my review, thanks to AndyKong for sending me YB04 with N6ii for a review!

Build and comfort: These are outstanding! Metal build I believe. This set is really comfortable and it comes with many tips; balance, vocal, bass, double flange, and foam.

Sound signature: Interesting tuning. This is almost like etymotic reference tuning. I will give two different sources here; apple dongle and n6ii pairing

  1. Apple dongle: The bass is lean. The mids is smooth and lush. Highs are well extended and really musical.

  2. N6ii 3.5mm T01: Straight up very musical. N6ii is indeed a musical dap that has a touch of warmth by giving bigger note weight. I certainly believe that there is a slight bump on 150Hz-250Hz for the warmth. With this warmth, there is like a perfect weight on vocals. Very crystal clear and musical mids. The bass is still in the leaner side but this time it is just better. More weight. For the highs; again, this is very well extended and very musical. Really musical pairing. I have an eq preset for Spotify Apple to mimic the N6ii, it’s not 1:1 same but you will get an idea at least! (Spotify EQ below for you to try)

Spoiler: To me personally, I happen to like 3.5mm on N6ii rather than its balance. The single ended seems more airy and open. Very wide soundstage than the 4.4 out. Weird. 4.4output happens to slam better but it has significantly narrow soundstage. Choose which you like the most.


Sonic presentation

Bass: The subbass is not really well extended but the mid and upper bass are well executed to give weight for vocals. This is not for dance/EDM type of song if you are into it.

Mids: With N6ii pairing, this set is AMAZING. Crystal clear and very lush mids. Separation of the mids is really pleasant and beautiful. Without the n6ii, just take this as less musical but the crystal clear retains.

Vocals: Both male and female vocals are excellent. It is almost like this set is designed for vocals. Lush and clear vocals with perfect weight. Regarding the tonality, by having n6ii, the tonality is excellent. Without n6ii, you need to increase the note weight a little bit in eq.

Highs: Very well extended! To me personally, this is a better set of Empire Ears EVR if you compare the highs. Straight up beating Rai Penta and EVR in terms of highs iirc.

Staging and Imaging: pinpoint imaging but not exceptional.

Soundstage: Width; very wide! Depth; Average :)

EarTips: I prefer best with balance tips that comes in the box. Yes, with N6ii pairing or EQed Spotify to mimic N6ii signature.


Test Track

13 Test Track Spotify Link:

Paint by Moonmoon: (Male vocal centric)
No doubt, no problem for male vocals. Pleasing sound, has a great weight for male vocals. The clarity is great too! The ending part with multiple male vocals is also very musical and well separated.

Love Alone by IU: (Female vocal centric)
Beautiful female vocals! It has weight, air, and clarity. There is no bass bleed at all to my ears. It is not even “too forward” kind of vocals and I like how it placed the vocals.

Angel by Chancellor and Taeyeon: (Duet Male and Female vocals)
A very well recorded track and hence YB04 delivers it beautifully. Male and female, both sounded very good. Very airy and musical at the same time. Layering is excellent too!

Every End of the Day by IU: (Female vocal centric with complex music)
Hard track and happily I would say this set did well. The layering capabilities with the soundstage performance helped a lot. The vocals is again smooth and does not sound strained at all.

POPSICLE by UHSN: (Imaging, complex, separation song)
Imaging is excellent but not outstanding as KSE1200 but again this is super great considering its price. It handles the complex and crowded part very well. Not harsh at all and very musical.

Occupied by Rich Brian: (Subbass and imaging track for male)
Again, this is not a sub bass oriented IEM. However the subbass is very clean. The male vocals here are really well pronounced, crystal clear and smooth. Such a pleasing tone and the imaging is great!

Your text by Sundial: (Soundstage and pinpoint imaging test)
The soundstage is wide. Everything is separated well and being placed at the right places. Very beautiful tone and the male/female voice is gorgeous too. No bass bleed at all. Pinpoint imaging great.

Bad guy by Billie Eillish: (Subbass and layering for female)
The subbass is controlled and lean since this is not a sub bass oriented IEM. The layering of multiple female vocals is flawless. Again, the vocal performance on this set is beautiful. I stress this again, with N6ii pairing or EQed Spotify to mimic N6ii signature.

Psychosocial by Slipknot: (Multiple metal instruments track)
The separation of guitars, drums, etc are well presented. The vocals are well presented. There is no any weird peaks on highs that can ruin your experience. I like how it sounds.

Feel Special by Twice: (Pop electronic music)
Very good sounding. I love how YB04 handles electronic music without sounding harsh at all. The N6ii also helps a lot making this set even more musical.

Blah Blah Blah by Armin van Buuren: (EDM, almost dubstep but not a hardcore dubstep)
Not the best set for you to dance in the club however the highs are well extended without sounding harsh. It has a minimal amount of bass for you to enjoy it but other sets can do better for you if you are an EDM banger. Imaging is very good though.

Cumbe by Rodrigo y Gabriela: (Can be a “typical” audiophile track?)
Excellent separation for all instruments. The guitars and the drums do not sound congested at all. Bass is controlled and hence the guitar sounds clear. The imaging is excellent!

Chicken Noodle Soup by j-hope and Becky G: (Pop Hip Hop Top 40 Hitz kinda of track)
Sounds great on this set though it can be better with bass impact if you want to enjoy this kind of track. However, the vocals performance is always on point!


YB04 vs EVR:
This has been a few weeks since Ive heard EVR so, take this with a grain of salt. However I can remember that EVR vocals presentation is superb. However, the highs are a bit veiled as in it rolls of pretty early before creating airy kind of feeling. For the bass the department, I can recall that both of these sets are almost equally the same. It doesn’t have much impact on this region but lean with warmth. YB04 excels on highs since the iem extends quite a bit and give the airy feeling.

YB04 vs Rai Penta:
Even Rai Penta is a hybrid with a DD bass, Penta doesn’t emphasis on bass. The bass is lean and just because of it is a DD bass, I can feel the DD texture in the bass region even though it doesn’t slam that much. For the mids, I think both sets are great. The mids and vocals can be a be a little difference but both are excellent. And again for the highs, YB04 exceed the highs of Penta. It has more details but still retain the smoothness and deliver music in a musical way.

YB04 vs IER M9:
Straight up M9 is a fuller sounding IEM. M9 with hybrid tips sounds intimate and engaging but not really open as YB04. However, with a bigger bore tips, M9 performs outstandingly good with amount of warmth and kick and still maintain the crystal mids and highs. Pairing it with N6ii is so musical and full of emotion. YB04 on the other hand tends to be a leaner side and still have tons of warmth to make the music rich. Just the A B comparison makes the M9 fuller than YB04. Without A B comparison, I can easily say YB04+N6ii pairing is full and musical and still a great set for a detail pickup. Plus, YB04 has above average soundstage!

The unique/Conclusion:
This is a good example of reference tuning that still carries musical emotion to it. It has warmth in the mids and vocals that made this set sounds emotionally engaging. The soundstage in term of width is really one of the factors for this IEM, really wide and well separated sound. However, it performs the best with N6ii. Hence, I tried my best to imitate the signature of N6ii into my Spotify Apple equalizer in order for you try it. Again it is not 1 to 1 sound but the idea is there at least. Picture attached; you can try with any eq app if you have it. Also, I love to bring Ipod/Apple dongle here because that's one of the most clean neutral source for me to know the benchmark of a specific IEM. Again, YB04 is a reference musical sounding with excellent vocals delivery!


-EQ for Signature imitation-
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100+ Head-Fier
Pros: Natural, non-fatiguing sound. Excellent build quality. Good fit. Amazing IEM case.
Cons: Bass light for my tastes. Cable could be better (being picky).
Disclaimer: As part of the Cayin N6II and YB04 tour I was lent these IEMs to try in exchange for an honest review. I am in no way associated with Cayin.

The YB04 is Cayin's first IEM and is positioned as a mid-priced multi BA over ear unit with a premium metal build and engaging, powerful, natural sound. The market <£1000 is pretty crowded, especially with all the new gems coming from China so lets see how the YB04 performs (in my honest opinion of course)...

The YB-04 specification is as follows;

  • Driver units: 4 balanced armature drivers; Tweeter: Knowles x 2; Woofer: Sonion x 2
  • Frequency response: 18Hz ~ 40kHz
  • Impedance: 30
  • Sensitivity: 113dB @1kHz +/-2dB
  • Enclosure: Machined CNC Aviation Aluminium Alloy
  • Headphone Cable: Unidirectional crystalized OFC, Silver Alloy
  • Input connector: 0.35mm TRS Singled-ended
  • Earphone connector: 2-pin 0.78mm
  • Price: currently £449

In The box:

In the (quite large) box you get:

  • YB04 IEM
  • 8 wire Copper/Silver alloy cable, 2pin 0.78mm
  • 12 pairs of ear tips (2 flange, bass, balanced )
  • The fantastic Tan leather case (plenty of space for the IEM + cable + tips). I would buy this case alone for my current earphones.
  • Cable clip
  • Cleaning brush and cloth
  • User manual
Unboxing is a nice experience, getting to the IEM is easy and all contents well protected. The box is actually quite large for what's in it - good protection I guess.

I really like the selection of tips, but after top rolling found the medium balanced to be my favourites.

I love the Tan leather case which has lots of space of the IEM, cable, tips, cleaning brush etc. and protects everything inside. It looks great, feels great and I could get 2x IEM in the same box (Fearless S8f & YB04). I wish more manufacturers would provide this level of accessory as I mostly use earphones on the move and need a secure case.

YB04 Case

Build Quality & Design:

Much like the N6ii, the YB04's build quality is excellent. Machined aluminium shells with screw on faceplates feel solid in the hand and look great. I particularly like the red and blue dots donating Left and Right orientations, useful when both shells look identical (the cable has identical markings too). The nozzle has a mesh wax guard and a very pronounced flange helping tips to stay in place.

Cable connection is via the standard 2pin 0.78mm socket so you can use aftermarket cables. Remember the actual socket raises out of the shell so the best connector would make use of a recessed 2pin plug such that the plug housing slips over the raised socket - just like the supplied cable does. This gives a very secure connection for all those times you pull and push at the cable connection (in/out of bags, dropping your DAP etc.).

YB04 cable detached

YB04 faceplate

The YB04 + Cable (had my own random tips on there for the pics)

I am not one to really care too much about cable 'sound'. To me the only thing that changes is the impedance. But cables make a difference in terms of practicality and looks. The included cable is totally fine. Looks nice, seems strong and well made. Very few microphonics when walking with the YB04 and well shaped over ear bend (although I would have liked to see some memory wire in this section so I could mould the cable a little more). The plug is a 3.5mm straight metal type with a long neck allowing insertion past thick DAP/Phone cases. Cable stain relief is OK, nothing special. Y split is a metal unit with a hexagon shape and a rubber slider to tighten the cables up. Cable length is 1.3m, not too long but still allows me to hold my DAP in front of my stomach whilst routing the cable through my shirt.


The shells are of a medium size, quite similar to my Freedom S8f (maybe a little larger) and fit in my medium ears just fine with no pain or pressure points. I should state here that I was using medium silicone ear tips which suggests the metal YB04 nozzle diameter is an ideal size for me. Isolation with universals really comes down to nozzle width/depth and tip size. I found medium tips work best and provide decent isolation - can gently hear peoples conversations at normal voice level without any music playing.

Surprisingly the shell didn't feel at all cold to my ear even though it's metal on skin, which is nice as I often have earphones dangling around whilst outside in the cold e.g. queuing to board a plane, riding outside in winter etc. The cable bend feeds easily over the ear and can be slightly moulded in place. I did find the over ear bend would loosen up a bit after some time and I had to re-adjust (some memory wire would sort that out).

The shell fits fairly flush with my ear and I can lay my head on a pillow without much discomfort.

My wife has small ears and tried the fit with medium tips. Again, the fit was just fine and she obtained a good seal without any discomfort. I'd say the shell size is spot-on unless you have very small ears.


TL:DR: Lovely precise natural tuning, with fast attack and natural note decay. Great sound stage, kinda puts you a few rows back from the stage. Excellent stereo imaging and not at all fatiguing. Probably not for bass-heads.

I tested the sound using the Cayin N6ii with my preferred EQ setting using the same music files, stock cable and medium balanced tips.

Before we get into it, the included tips pretty much do what they say on the tin - bass tips = more bass, balanced = more balanced, vocal = more high-mid/high end, bi-flange = better isolation. After listening to them all, I found the medium balanced tips to be my favourite. I would have bet a lot of money that I would have proffered the bass tips before testing, but 'balanced' and natural seems to be the tuning for these IEMs and using the bass/vocal tips seem to make the sound a little artificial and break away from the IEM inherent tuning. Bi-flange is OK and sounds a little more bass heavy, but I have never liked the way bi or triple flange tips feel.

Tracks I used are as follows:

  1. AC/DC - Sin City (FLAC)
  2. Black Sabbath - Children of the Sea (FLAC)
  3. Portishead - Numb (FLAC)
  4. Infected Mushroom - Heavy Weight (FLAC)
  5. Nirvana - Where did you sleep last night (FLAC)
Music impressions:

  1. AC/DC - Sin City (FLAC) - Symbols at the start of this track sound great and pronounced alongside solid midrange guitar rhythm and not overpowered by the bassline. The bassline itself is there but not overly extended. It seems the more mid-centric tuning gives this track a natural flavour, but I would like that bassline to shine. Bon's vocals are front and centre here and appear layered right on top of the instruments. At no point does this track sound congested - which I have found happens when bass bleeds into the lower mids.
  2. Black Sabbath - Children of the Sea (FLAC) - Tony's beautiful guitar sounds airy and natural, almost like he's sitting next to me. Again, the bassline is there but does not power through like I have heard. Dio sounds wonderful even when he goes deep. Bill's drum rolls sound great and move L to R well (thanks to the stereo imaging) and the fast attack really brings them to life.
  3. Portishead - Numb (FLAC) - As a glorious bass track, I could have done with some more low end. Even then it still sounds very musical (musical and fun is my general taste) and Beth's vocals come flying through the ensemble. Those light symbol strikes also shine.
  4. Infected Mushroom - Heavy Weight (FLAC) - This is a very holographic track (loads of sweeping sounds L and R) where the sounds seem to come from all around. That aspect is very nicely presented by the YB04. Top end sparkle all there and but bass is a bit light, which does not benefit the track. I'm a big drum freak and at 04:34 the drum beat sounds fast and musical. Vocals and guitars both sound natural and are right up front when they come in.
  5. Nirvana - Where did you sleep last night (Live, FLAC) - NOW YOU'RE TALKING! Man, Kurt really did an exceptional job didn't he! and it's all good on the YB04. I listened to this track over and over, even without the deeper bass notes I can close my eyes and I'm in the studio with them. This track brings out the best in the YB04 and I wonder if they didn't listen to it when tuning :)

Bass: Bass is there but won't slam your brain - but certainly not 'thin' sounding. Saying that its very detailed probably thanks to the speed of the YB04.
Mid: Fantastic note weight and fast guitars are not lost or congested. Male and female vocals are equally great.
High: A combination of fast attack, natural decay and great imaging produce wonderful musical sound that moves around your head. Extension is all there and does not seem to roll off at all, giving a very airy quality.
Sound stage: Right in the middle of the stage, a few rows back.
Other: The natural mid-centric tuning (to my ears) shines for acoustic music and the YB04's speed definitely works on rock tracks, preventing them from becoming loose or congested.

I did listen to this with my Cowon PM2 which adds some bass but the result is quite similar to the above comments. Cayin achieved great synergy with the N6ii ad YB04, but that's not surprising.


The YB04 is probably No.1 from all the (what I consider) mid-centric IEM's I've listened to, from Empire Ears to 64 Audio to JH Audio. Cayin really has the tuning spot on if you love acoustic/classical/rock music or want a very non-fatiguing, natural sound. At this price range there is a lot of competition but the YB04 shines through when you look at sound, build quality and ergonomics. If you're looking for a natural sounding, non-fatiguing IEM with excellent build quality and top accessories, definitely listen to the YB04.
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500+ Head-Fier
Pros: Neutrality
Cons: Amount of bass
Clear side for some
Neutrality for others

YB04 are a demonstration model courtesy of Cayin as part of the Head-Fi tour they organized and launched early November.


Cayin is a Chinese company well established in the world of traditional Hi-Fi for more than 25 years now. In recent years, she has become interested in nomad Hi-Fi and particularly DAPs, with gears providing very good services at the attractive prices at which they were offered.

With the YB04, Cayin is finally entering the in-ear market. In an aluminium shell with visible screws, you find 4 balanced armatures that manage the entire frequency response. The elegant industrial look seems very strong and capable of resisting drops. The stock cable is of great quality and ergonomics are good, except for the earguide which I find very unpleasant. I managed to have an excellent fit with the enclosed tips.
The YB04s are available for €598 in Europe, and $399 in the rest of the world


The YB04 signature is a rather balanced one. We feel that the wish is to aim for a reference signature.
Here are the Crinacle measurements (uncompensated) to compare with the InEar PP8.

The mids are for me the real success of the YB04s and Cayin's tuning is quite incredible. Indeed, they have a very good tone and are both airy and full. Their dynamics are excellent and contribute to this overall feeling of speed. Low Mids (250 to 500Hz) is confoundingly neutral, allowing the recording you are listening to to express itself fully, just like on PP8. Fusion is thicker and denser in comparison. The Mids (500 to 2000Hz) are aerated by means of the relative dip from 500 to 800 and then the steep rise to 2000Hz. This brings a real openness and fullness to the voices that seem to be dull on the PP8 in comparaison. On the Fusion we are smoother and less technical. High-Mids (2000 to 4000Hz), despite a hole to measure, remains consistent due to the peak at 4000Hz. It allows not to give too much intensity to the voices which remain soft and never aggressive, but a little more defined than on Fusion for example.

The bass, as the curves suggest, is there but in a moderate, even discreet way. Present in quantities equivalent to those found on PP8 switch off, they are relatively dry, without emphases and very fast on impact. Maybe even faster than on PP8. Their naturalness is enjoyable. Subs (20 to 60Hz) are present but without ever really giving the pleasant boost to modern music like Hip-Hop or Electro and that can be found with the switch Bass on PP8. The Bass (60 to 250Hz) are very lively here too, with a very good resolution level. All this gives a light and delicate bottom foundation that undoubtedly helps to make the mediums the party kings.

Highs are extended, more than on PP8 but less than on Fusion I think. They are neither too forward nor too far back. The key words are softness and transparency. The peak at 6000Hz, clearly audible to the sweep, gives clarity without bringing hardness. It certainly contributes to the very good clarity of the entire restitution. The speed of the treble is also to be underlined because it brings a dynamic side to the whole message. The result is treble range on the clear side, more than on Fusion for sure, but not itchy.

Soundstage is of very good craftsmanship. The stage width is excellent and comparable to what PP8 or Fusion offers. The depth is good, it seems to me to be greater than that offered by the PP8, but a little less than on the Fusion. The height is also good, between PP8 and Fusion once again. All this allows a proportionate and very pleasant image.

The magic square is of a high level and finally quite comparable to what PP8 or S8Pro offers. Special mention to the resolution and separation which are exceptional for an intra of this price, and superior to what PP8 offers. Combined with soundstage this offers a first-class layering.

Tips and Pair Up

For tips, among those provided I retain the "Balanced Eartips" used for the feedback, and whose rendering is very close to Whirlwind or JVC Spiral Dots. These are the ones that best allow the YB04 to express their soft neutrality.

For the DAP, association with the WM1Z K mod served as the basis for the return.
The switch to the Cayin N6 A01 gives more thickness to the midrange and more musicality, the synergy is very pleasant. The stage shrinks a little in width and depth, but increases in height. Bass moves back a little bit where treble seems a little more present. Resolution, definition and transparency seem to me to be on the decrease.
The N6 T01 compared to the A01 provides less extension at the top, and a more neutral midrange, close to what the 1Z offers. The resolution seems better too. But a step does still exist to the 1Z K mod.

Final Thoughts

Neutrality, resolution, naturalness and musicality ! It is the winning quartet that makes the YB04s a great success in the less than 1000€ in-ear clear signature sector. Be careful with the slightly light basses, which will not be suitable for those who like big impacts.

"Resolution is the ability to individualize a voice or instrument"
"Separation is the ability to feel space between the various sound sources"
"Definition is the ability to perceive as much information as possible"
"Transparency is the ability to transcribe the nuances and subtleties of music"

My topic on Tellement Nomade here :
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200$ and above lol. Ok. Ideally under 500$. May go 800$.
YB04 is a good pick then.
Great review! If I read correctly, I think YB04 is overall the better performer and value-wise compared to PP8.


Pros: Spacious soundstage
Pinpoint imaging
Detailed Mids
Large amount of accessories
Cons: Not really for basshead lovers
Smaller ears might not get a good fit
Cayin YB04 Review

Big thanks to Andykong and Cayin for supplying the tour package for the Cayin YB04 and the N6ii Mk2 A01 + T01. It was an amazing experience.

They come with 12 different ear tips, a storage case, a cable clip, 1.3m 3.5mm cable, a cloth and a cleaning brush.

In terms of tips, they come with a small, medium and large vocal, balanced, bass tips as well as a medium bi flange ear tip and two medium sized foam ear tips.

The cable itself is nice, it has labeled connectors for the left and right as well as blue and red marks to say so. The design itself seems very much on the sleek/minimalist side and not too loud looking. But to me it looks amazing and goes well with the IEM design.


And the storage case, it reminds me a bit of the Tin T4 case design, but it has more room for storage, a lighter shade on the inside and a much sturdier feel to it. It seems sturdy enough to put in a bag on the go with enough room to fit some tips, and the IEM + cable itself.

Fit and Comfort

They were decently comfortable for a bit but personally for me, my ears are a bit on the smaller side, and it was a bit of a tight fit even on the smallest ear tip provided. After about maybe 3-4 hours I could feel the weight on it around my ear canal, possibly due to not the best fit. The bi Flange and foam ear tips were not usable for me, generally I use SS or S ear tip sizes. Sedna ear fit light, AET07 and AET08 were other ear tips I tried but experienced not much better comfort, nozzle might just be a bit too big for me.
Just a random thought on the ear tips. Although not a huge issue sometimes I felt the ear tips were a bit snug to fit on, namely only the stock bass, vocal and balance ear tips. Sometimes it would just go on easy in a second and other times it would be difficult and take a minute to put on. For reference it sorta was a bit tight on the Azla and AET ear tips as well.

Sound Isolation

It was on the decent side, a lot of the time I could really just exit the world at home any ignore the TV going on in the living room, or anyone knocking on the door and blocking out a lot of conversation which was great. They don’t completely block you out though as doorbells, a mechanical keyboard, and possibly a timer would still be noticeable.

Power Requirements:

These IEMs were not hard to drive at all, barely needed any power. But the issue lies as these are very sensitive to noise. My LG v20 couldn’t really do the job. My JDS atoms though was able to give the blackest background in terms of noise.

The sound:

I ended up liking the balanced ear tips the most with my time, but it was close vs the bass and vocal ear tips included. If I were to summarize the sound, I would say neutral with a tad amount of brightness.


I ended up using SDAC-Balanced -> JDS atoms, foobar2000 with flac files only.

I tried this on my LG v20 phone, and it is just unusable on it, would not recommend. These IEMs are sensitive.

As well as the Cayin N6II MK2, using the Cayin music app included in it, with the A01 and T01.


The bass to me follows what most people would describe as BA bass, it is fast in its decay, it is very much not really emphasized in any way. Though this is my first time with a BA at home I think understand what it is now. It is not the leanest amount of bass I ever heard but it is on the leaner side. For reference switching to my HD 580, I felt as if that way bass heavy when I tried it on the same songs. Although the bass ear tips help the extension these really do not have a large amount of slam, punch or rumble. Sub-bass especially felt mostly absent in songs like “Dark Knight: Why So Serious?” by Hans Zimmer, there is a part in the song where it is just sub-bass and it really isn’t there with any of the tips I had. Although in my usual pop and rock songs I felt like the bass amount was fine and didn’t really yearn for more. Hip Hop or Rap on the other hand wasn’t a recommended genre for these IEMs. When I tried to EQ the sub-bass up, I found that it really needs a lot to make it bass heavy, for general use I decided to put a low shelf on 125 hz down by 2.5 db.


Pretty vocal forward was my first reaction when I listened to the YB04. I generally have a decent set of female vocal tracks on my playlist and with the YB04 I felt as if the range around the 1-2k region was just a bit too emphasized. Generally, I find that region fatiguing to me ears, although this was not fatiguing in this case. I EQ’d that part down about a db and felt like the middle of the mids needed a bit more body by like .5-1db. Overall though, the mids really stood out to me as the best part of the IEM such as the detail retrieval. Not much has really stood out to me as detailed in the mids until now and the micro detail on it was amazing for the price. Something else that really popped out at me was that vocals usually and guitar strings really felt as if you are hearing a holographic image. With my finished EQ, it sort of reduces this effect but it still remains there which was interesting.


Treble was interesting as most of it isn’t too bright. For the peaks around 3.5k-4k, 5.5k-6k, around 7k, slight peak in 9.5k and a slight peak in 12k. The biggest peak is the 5.5k-6k region although these peaks weren’t crazy. Between those peaks there are somewhat big dips. I didn’t need much EQ to put it to my preferred sound, at most I was using about -2.5 db. The YB04 didn’t really come of as airy much past the 12k region.

Tips Sound changes:
Generally as the tips say, the bass ear tips appear to have the most extension followed by the balanced then vocal. The brightest ear tips I found to be were the bass ear tips then vocal ear tips then balanced ear tips. Although, I didn’t find a huge change with these ear tips included to the point that I could be imaging the difference in brightness. The biggest change being the bass extension to me. The included Bi Flange I want to say is somewhat near the balanced ear tip sound, but I didn’t find the fit well. They all mainly retain the same peaks and dips when changing the tips. I also tried the AET07, AET08, and Azla Sednaearfit light, but those didn’t change the sound enough and I still preferred the balanced tips included.


So, the detail on these were overall pretty decent especially for the price, I believe I saw these for $369 on BF and that seems like a great price. The bass micro detail to me was decent and able to compete with the RE2000 I tried earlier. The micro detail in the mids was great and I felt surpassed the RE2000 in a lot of my songs. The only part where the RE2000 is just in a different category would be the bass texture, slam and just how visceral the bass can feel and sound. The YB04 could not put a finger to it in that category.


To me the separation seemed fine and didn’t have too much issues with any of my songs although they were not much to write home about.

Soundstage and imaging

This part surprised me a lot, I was expecting this IEM to sound like another head space-ish sound and have average imaging at best. Well this IEM is amazing with imaging, to the point that I sort of want to say that it even does imaging better than my HD 800. Songs like Yosi Horikawa Letters, Wandering, Tundra by Amber Rubarth and Chocolate Chip Trip by Tool really felt as if I was in the music and was immersive. The soundstage as well was just large enough to not lose out any of the imaging aspects of it and not sound as if the music is inside your head. To compare to the HD 800, it really has an almost unnaturally wide soundstage and sometimes with that it can make it feel like the imaging is not as precise or hard to pinpoint. As well as combined with the fact the HD 800 seems to not be able to get as intimate as the YB04. These two alone are amazing to hear for such an affordable price and make me wish I didn’t blow all my money on 11.11.


The RE2000 exceeds the bass of the YB04 in terms of enjoyment if you are a bass lover. Personally, for me I find the RE2000 way more fun sounding there and the bass is so textured and visceral that I can’t really find in headphones for that price until I go in the 1.5K+ region to get a hint of it. The YB04 although I find more enjoyable with how the treble is tuned and it has competitive mids and treble detail in comparison to it. As well as the YB04 doing soundstage and imaging much better. The timbre on the RE2000 is not perfect but the YB04 is closer to perfect.

Would I buy it?
Although I just bought an IEM that was similarly priced, and has some similar characteristics that it does well in. I wanted to compare those two, but it just didn’t arrive in time. With my current experience in IEMs I really feel that this is a compelling offer for anyone that doesn’t require bass head levels. As I am a bit of a bass head, I am sort of warming up to it to my other songs and find it enjoyable. I might do a comparison later to see if I still believe this but for now, I would buy it.


Pros: Well balanced mids and highs
Wide and airy stage
Good timbre
Great accessories
Cons: Lack of subbass extension
Not enough bass in general to be an all arounder
Average fit due to size
Big thanks to AndyKong for sending the YB04 over for review.


The YB04 has been burned in for 100h prior to critical listening. Majority of the listening has been done using Cayin N6ii with both A01 and T01 boards.

Packaging & Accessories:
The IEMs come in a fairly big box with a fair bit of weight to it.

The presentation feels very premium, with everything being well secured and thought out.

The amount of accessories is quite impressive, especially when it comes to tips choice. Having 5 types of tips to try with the IEMs is a very good starting point to both get a good fit and tune them sonically.

Build Quality
The build of the IEMs is solid, the shell is smooth and well machined. The coating feels and looks premium and should last the normal usage without issues especially if they are kept in the provided case.
The case itself while big is very well built, needs a good amount of tension to open and close so it shouldn't open accidentally.
The cable is a bit weighty but the ear hooks help to relieve dissipate both its weight and the weight of the IEMs.

Unfortunately for me, the fit was average at best. The size of the shell made it quite finicky to get a good seal and keep the IEM comfortable in my ear. This is obviously something that will vary from person to person but you should consider those are fairly big.
For reference pictures next to CA Andromeda:



Subbass extension is fairly limited, listening to songs like "Bonefield - Window" you can tell the notes die out way too early and don't fill the stage the way they should. The midbass is quick and snappy but lacks the punch and can feel anaemic at times. This definitely doesn't render those IEMs quite genre-specific and if punchy bass or good subbass extension is needed then they aren't a good choice.

Sweet and clear. No matter the source those two characteristics were always present. Timbre was very good across the instruments, notes had a decent amount of weight to them. With the N6ii, the midrange gained a nice sense of warmth and fullness which translated into making vocal-centric music extremely enjoyable. The detail was present but not overbearing or in your face.

Well extended, smooth and detailed. Again very good timbre and transients, cymbal hits had a nice bit of sizzle to them. There was no sibilance or harshness to be found. They also produce a very nice sense of air no matter how complex the tracks are.

Imaging & Soundstage
The stage is probably one of the biggest strengths of YB04, It's wide and airy, with very good separation and imaging across. It's not the deepest but the width partially covers for that.

While the tuning of those isn't something I would call mainstream, they are still an interesting offering due to their midrange and highs and general coherence to the sound. They also offer a wide range of accessories and good build quality. My main problem with them is the bass, I can understand the tuning nature of it however, the subbass extension is quite disappointing at this price point. The fit could also prove problematic for certain people so I recommend you demo those before purchasing if possible.


500+ Head-Fier
Pros: Beautiful to look at and handle

Non-fatiguing but never boring or flat

Cable responsive
Cons: Eartip choice crucial

Should have a balanced cable as standard

Excessive packaging
Cayin YB04 4BA earphone – Genuinely Joyful


Unboxing & Package contents:
Large black clamshell box with the IEMs, mid-brown leather case, cleaning brush and cloth, cable clip, 4 cards of various silicone and foam tips, 3.5mm copper/silver 8 core cable. The box is needlessly huge with far too much foam packing. It could easily be done in half the volume and still be a pleasant unboxing experience. There should be a degree of corporate responsibility for environmentally sensitive packaging.

The YB04s are sleek, brushed metallic round-edged polygons. Very slippery in the wrong hands! The connectors are raised 2 pin 0.78mm. The right-angle connectors are slightly shrouded but there is no impediment to a flat or standard 2 pin cable. They feel well machined, solid and of quality.​


The cable is beautifully made; the silver and dark brown copper strands complement the metallic tones of the YB04 and the case in a harmonious fashion. It is a real shame that it is unbalanced. Seems like a waste of 8 cores. Cayin has missed a trick here – they should have taken a leaf out of iBasso’s book and supplied a balanced 2.5mm cable with a 3.5mm single ended adapter. I will be using my own balanced cables.

The hard carrying case is a little plasticky to the touch but there is plenty for space for tips, cable and the IEMs. A tasteful departure from the usual black or carbon fibre finishes.

Sensitivity:113 dB
Impedance: 30 ohm
Plug Type: 3.5mm
Pin Type: 0.78mm
Frequency response range: 18Hz - 40KHz

Single flange silicone tips are never any good for me, so I switched out to the supplied foam tips and my own Spinfit CP240 biflange tips. I could not get a good seal (which is unusual for me with the Spinfits) and so tried some generic large triflange silicone tips. The change was miraculous – gone was the weak bass, washed out soundstage and attenuated timbre.




iBasso DX228 (Mango OS, High gain, Digital Filter 3)
Cayin N6ii (Hdb, Sharp Roll-off)
Penon 4.4-2.5mm 8W SPC adapter
Cables: NiceHCK 16-3, Penon CS819, Effect Audio Ares 8W, Fearless Audio 8W SPC, Electro Acousti (EAC) 8W OCC / AgAu
All the cables and DAP hardware are my own. The N6ii and YB04s are free loan units from Cayin Audio and will be returned to Cayin at the end of review period.
A mixture of MP3, 16/24-bit FLAC, DSD256.

DX228 Sound:

Lows: Although the response could be described as a fairly neutral but typical balanced armature bass, there is nothing wrong with this per se. It is impactful in both the mid and sub bass regions but only when called for. There is accurate timing, tonality and speed. Best brought out by the Ares but amazingly clear and precise with the Fearless. The EAC expanded the soundstage with a bass in between the Areas and Fearless.

Mids: Beautifully balanced but with a hint of warmth. Vocals are sweetened but only as far as they need to be. The best way I can describe them is proportional – represented as and when needed. Again, best brought out by the Ares and Fearless. All of the hybrids were ever so slightly recessed except the EAC.

Highs: Overall clear with a hint of hardness depending on cable choice; never strident although the Penon was edging towards that. Again, really easy to listen to, non-fatiguing. Again, Ares were warm and rich but not especially rounded off. Best appreciated with the Fearless / EAC.

N6ii Sound:

Strangely I did not feel that this was as synergistic a pairing compared to the iBasso. The iBasso has a wider soundstage, was more energetic and lively compared to the ever so slightly warm and smooth Cayin. The vocals were more intimate but no less acoustically pleasing on the Cayin across all the cables. Only the Fearless produced a comfortable, pleasant sound with any copper sounding far too harsh and metallic and the hybrids washing out the timbre and blunting the tonality.

I tried the supplied 3.5mm single ended cable with the Cayin: The obvious difference between single ended and balanced applies – minor reduction of separation, resolution, and soundstage but otherwise a decent sound with appropriate bass but some congestion and stridency towards the upper range.


Wide with average depth and height – better with hybrid cables but deeper with the Ares and Fearless.


For the balanced, energetic DX228, I would suggest a hybrid or SPC – but it is best suited to a higher quality 8 core. The 16-3 did itself no favours with a dry, hardened timbre.
For the warmer, more intimate N6ii, I would suggest the SPC rather than the copper or the hybrid, which were both a little edgy and dry. The supplied 3.5mm cable is perfectly adequate but a balanced SPC takes the sound to the next level.


I wasn’t expecting to like the YB04s as much as I did, once I got the right DAP, tips and cable. They are well made, easy going but not laid back, comfortable for long periods of time and a delight to use. Not for someone who wants a huge amount of bass but I often found myself performing air slap bass (a la Mark King) because the tunes were so engaging. Not something you need to see but nonetheless, a marker of enjoyment.


Headphoneus Supremus
Pros: first rate build and cable, neutral signature and natural tonality, great kit
Cons: Large shells, only average isolation, bass is neutral to slightly lite which wont please some.

disclaimer: I was sent the Cayin N6ii and YB04 as part of the Cayin North American Review tour. Thank you to Cayin for providing the opportunity and trusting me with their gear. If you have an interest in Cayin products, more details can be found at Cayin’s Website. Cayin products are sold in North America by Musicteck.

Unboxing / Packaging:

While the asking price is mid-fi, the packaging certainly qualifies as high end. An outer slipcover keeps a book-fold style box closed for transport but is easily removed when needed unlike some that required considerable force to dislodge the inner package. The inner box is equally divided with the tips, books, case, and accessories on one side, and a foam surround cradling the earpieces and cable on the other. The foam has cutouts to allow easy removal and at the same time is a tight enough fit to protect the contents well. The case is a rectangular leather clamshell type with ample room for the cable and earpieces without feeling crowded (Nice touch as too many are too small), Multiple tip options are presented on cards to keep them organized, again, exceeding the norm at this price-point (more on this later). The only hint that the YB04 is closer to mid-fi than flagship is the lack of a balanced cable in the kit.

Cayin-yb04-box-front.jpg Cayin-yb04-box-rear.jpg Cayin-yb04-box-open.jpg Cayin-yb04-box-right.jpg Cayin-yb04-box-left.jpg Cayin-yb04-kit.jpg


The YB04 is a 4 piece shell consisting of nozzles, inner shell, an outer ring that seals the bi-pin connector to the inner shell, and a faceplate. All except the nozzles are made of the same aluminum alloy and polished to a brushed metal finish. The nozzle, while also aluminum, is a different alloy and polished to a lighter and brighter finish than the rest of the shell. Nozzles are T400 size with a pronounced lip f0r holding tips in place. The nozzles themselves are fairly short, but sit atop a riser that is roughly the same height as the nozzle itself and offsets the nozzle significantly from the body of the earpiece. This allows for fairly deep insertion. L/R are marked on the Riser at the front of the earpiece with a colored dot immediately below the connector for quick reference.

Shells are on the large side, but sit mostly on the ear rather than in it so comfort is reasonable for long periods for me, but I would certainly recommend auditioning a set before purchase as they are larger than most. Isolation is only average as the body does little to block the canal so realistically the tip is the only thing doing so. While my first thoughts were these looked large, heavy, and uncomfortable, I found them to be more comfortable for long wear than things like the Hifiman Re2000s, or the CCA-C12 as these later two fit more in the ear than on and create pressure points which the YB04 did not.

Cayin-yb04-shell1.jpg Cayin-yb04-nozzles.jpg Cayin-yb04-feature1.jpg Cayin-yb04-shell2.jpg Cayin-yb04-faceplates.jpg Cayin-yb04-sides.jpg


Thy YB04 is a quad balanced armature using two pairs of drivers. At the Low end, a Sonion made dual woofer package is used. Cayin doesn’t state which but odds are pretty good it is either a 3800 or 3300 package. My bet would be on the 3300 series as it is a bit flatter in the mids than the 3800. For the top end, a Knowles package with two drivers is used. Here again, no detail is provided but the most likely options are either a twfk or an swfk package. Crossover duties are handled by a 2 way resistor/capacitor cross. The pictures below show Cayin’s exploded diagram and a couple of shots of the actual internals of the review pair. Nominal impedance is listed as 30Ω with a sensitivity of 113 dB/mW which makes the YB04 fairly easy to drive. Having said that, the YB04 definitely benefits from more amplification than the average phone or tablet can provide and even the LG on high output is marginal. Cayin of course recommends the N6ii as the prefered source for the YB04 and they do indeed pair well, but I found the Sony WM1A, Dethonray DTR1, Xduoo X20, and even the Shanling M1 to be capable of driving the YB04 well. The YB04 scales qualitatively as well with more detail being heard with improvements in source.

YB04-internals1.jpg YB04-internals-label.jpg


The cable provided with the YB04 is a 8 core hybrid with 4 strands of oxygen free copper and 4 of silver alloy. Strands are covered in a clear PVC giving the cable a pleasing striped look. Starting from the south end, the cable starts with a straight 3.5mm TRS connector housed in a hexagon shaped metal housing that matches the color of the earpieces. A small set screw holds the plastic strain relief in place at the exit of the jack. the 8 core braid exits the strain relief and runs to the splitter. The splitter matches the barrel on the jack and has a proper strain relief on the lower side and then exits as two separate 4 wire braids as the wire heads for the earpieces. A small translucent plastic hexagon chin slider fits tightly to the top of the splitter when not in use. The north end of the cable ends with pre-formed earhooks without memory wire and hooded bi-pin connectors. The connectors themselves have clear housings, .78mm pins, and are well labeled with both L/R markings and a red dot on right for quick identification. I hesitate to call these QDC connectors as they do not have the reverse polarity of the QDC but are similar in style.

Cayin-yb04-jack.jpg Cayin-yb04-splitter.jpg Cayin-yb04-bi-pin.jpg Cayin-yb04-earpieces.jpg


As mentioned earlier, Cayin provides a larger than average selection of tips with the YB04 with bass, vocal, balanced, double flanged, and memory foams. The bass/balanced tip options have recently become more popular as Simgot ships those two styles with most of their line, but the addition of the vocal to the mix is not as commonly seen. While I started to write up something about each of the tips, I thought it better to let the measurements do the talking so I have included graphs of each compared to the default balanced tip. I used the balanced tips for all my listening notes. insert in my canals. As a result they feel less comfy and they stick out. The seal is there but it doesn’t look or feel very nice. I’d need bigger ear canals for this tip selection.


Balanced tips used for Frequency Response graph.


Beginning at the bottom end, the YB-04 has typical sub-bass for an all balanced armature model. Sub-bass is present, but not emphasized and falls a bit short of having that visceral feel most look for. What is there is tight, fast and better textured than most, but it won’t please the bass-heads in the crowd and it may seem a touch lite even for those who prefer a more balanced signature. Mid-bass is more present and follows the same pattern, fast, clean, and well detailed, but with a very slight emphasis that gives it a bit more presence in the overall mix and provides good slam when called upon. The YB04 is somewhat tip dependent, and bass ranges from lite to near neutral to odd. For me the bass tips gave an odd tonality when I listened using them so I quickly moved back to the balanced.


Mids are the dominant feature of the Yb04 but not in an “in your face” kind of way. The very slight warmth in the mid-bass combined with a very linear transition into the mids gives the YB04 more lower-mid presence than most and a gentle push in the upper-mids brings vocals to the forefront. timbre is mixed as the YB04 relies more on speed and articulation than brute force to deliver its message. Acoustic guitar sounds more natural than its electric counterpart as a result. Vocal presentation is engaging and well nuanced for both genders without sounding like one is in front of the other. The best feature of the YB04 to me is the tuning of the upper-mids, they have enough energy to be well present in the mix, without that over-done feel that is so common to those models with the upper-mid/lower treble push. These may not be as flashy or lively as some, but they are a much more natural presentation than most at this price point.


The mild upper-mid push is carried over into the lower treble with just enough added emphasis to really bring percussion to life without getting metallic or harsh. High-hat has a satisfying clap and snare rattle is precise and crisp. Detail in the lower treble is quite good which is almost expected from a ba anymore. Upper treble drops back a bit which keeps the Yb04 from getting fatiguing, but does add some air back into the mix and keeps the YB04 from sounding overly closed off. The YB04 manages to walk a very thin line between feeling closed in and unnatural on one side and fatiguing and treble inflated on the other masterfully.

Soundstage / Imaging:

This is another strong point of the YB04. The Stage is well dimensioned with a bit more width than depth, and good height. I’ve said that same thing about many iems, but with the YB04, the excellent stereo separation and imaging make the most of the stage and you lose some of the feeling that the shape is wider than deep as a result. Seating the orchestra is straight forward with very defined margins between instruments and movement is easily tracked on the stage. Layering is equally impressive with complex passages being easily handled without thickening or slop.


As a side note, Cayin recommends the YB04 be paired to the N6ii and I did find them to be a good pairing with the A01 module as the A01 is a bit warmer and thicker and the YB04 is a bit on the lean side so the combination really works. The two play off each others strengths to deliver an really enjoyable performance. The T01 module on the other hand is a bit thinner and more clinical and while yielding a near neutral performance, the combination came across as a bit lifeless in comparison to the A01.

Other than the N6ii, I found the YB04 paired exceedingly well with the Opus#1s with its slightly warm tilt and perhaps oddly with the iFi xDSD. I say oddly as the xDSD shares the burr brown dac of the T01 card but was warmer and a bit more full than the T01 by comparison.

Thoughts / Conclusion:

2019 has seen a lot of companies enter the earphone market and a lot of others jump up price brackets to release models in the mid-fi space. To say it is a crowded market is a serious understatement. It has also been a year when the name Knowles has been tossed around a lot as if it was the holy grail of balanced armatures. Sonion has quietly been building extremely good drivers and is giving Knowles a run for their money as evidenced here. The fact that Cayin chose to source parts from both shows a willingness to go after the best components regardless of the extra complexity added to sourcing, balancing, and managing those additional moving parts. A lot of other companies might have settled on Knowles or Sonion drivers to simplify the process. The result of that extra work pays off in one of the best sounding freshman iems on the market. It isn’t perfect as the size will scare some off and the lack of boosted bass will be the kiss of death for others, but the YB04 is a very solid (both physically and sounding) effort and shows that Cayin has some prowess in this space as well as in amps and DACs. If you like an iem that has a natural sound on the thinner side without a big bass boost or an artificially warm signature, the YB04 should be on your list of iems to audition. I am seriously considering shelling out for a pair when the tour package leaves my possession. That probably says more than anything else I can.
'It' being the A7? Thank you for your input! All these iem options are not good for my wallet.
yes it being the A7
Thank you! That will be my next one then


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.
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Hmm, very different thoughts than mine. I wonder if these are just different preferences, unit difference or problems with pairing with the source 🤔


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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