Oriolus Traillii (JP)

General Information


Oriolus Traillii JP
The latest flagship model from Oriolus
3-way 8BA 4EST (2 lows / 6 mids / 4 highs)
Includes PW x HYLA Arthur RT-1 flagship cable (worth $2270)
Retailed for $6000
Available in both UIEM/CIEM

Latest reviews

Small IEM with a BIG Sound!
Pros: hybrid (8BA/4EST) design, natural full body detailed tonality, powerful bass, balanced sound sig, 3D holographic soundstage, durable compact shells, premium PWA cable, VanNuys carry case.
Cons: price, universal fit only, and... price.

The product was provided to me on loan from MusicTeck for the review purpose in exchange for my honest opinion.

Manufacturer website: Oriolus Japan. Available for sale from MusicTeck.


The only time I use preamble in my reviews is when I talk about cables because I find that discussion to be a rather controversial topic which needs some additional explanation before the Intro. So why would I start IEM review with a preamble? Because I need to address the elephant in the room, the price tag of Oriolus Traillii which is $6k. When I heard how much it cost, a thought ran through my mind that we crossed yet another price threshold and now entering a new chapter of premium IEMs. But is this really a new chapter?

Every time I review flagship IEMs, I get asked about different premium cable pair ups. And some of my readers are well aware of Nic’s thread on Head-fi where I see a lot of discussions from head-fiers who use their kilobuck IEMs with high end cables. The price of Traillii is not for everybody, but there is a number of audiophiles who already own $5k-$6k IEM/cable combos because they want to squeeze out every ounce of performance, don’t mind diminishing returns, and still find it cheaper than 2 channel home systems where a power cable alone can cost as much.


So, let’s put down pitchforks and torches, and if you are still curious about this new IEM release from Oriolus with a premium PWA cable, proceed further to read my review of Oriolus Traillii latest hybrid flagship.


Actually, this review feels a bit like a déjà vu from 2018 when I visited Oriolus/Hyla table at CanJam NYC and heard Oriolus Mellianus for the first time. I couldn’t get its tuning out of my head and just had to review it. Now, 3 years later, I continue to use and to feature Mellianus in a number of my reviews as part of comparison and cable pair ups. Fast forward to 2020, and I saw the announcement from MusicTeck about a new Oriolus Traillii flagship which of course caught my attention even before I read the price.

My original plan was just to hear them without a commitment to review, and I was happy for the opportunity to spend a few days with Traillii. While I’m trying not to use the word “spoiled”, I do feel a bit jaded after having a chance to hear and to review so many different flagship IEMs, to the point where it is hard to get excited about another one. And as usual, I didn’t know what to expect, but after putting these in my ears, I immediately asked MusicTeck if I can hold on to them for a few extra days so I can write full review.

Another interesting thing was Traillii being released under Oriolus and not Hyla name. For those who are not familiar, Oriolus was formed in 2015 under the umbrella of Cyras Co. in Japan, and had a number of successful IEMs, DAP, DAC, and Amp releases. In 2017, Cyras added a more upscale line of IEMs under Hyla name, though this latest premium flagship release ended up under Oriolus name. But regardless of the name, what really counts here is how this little bird sings, so let’s proceed to find out more.


Unboxing and Accessories.

Arrived in a smaller size plain carboard box, inside you will find a custom VanNuys storage carry case which is pretty much the whole packaging of the product. VanNuys (Japan) are well known in audiophile world and usually hard to find outside of Japan. This ballistic nylon multifunctional case with Oriolus name on the cover has a padded poly mesh inner lining and adjustable velcro partition to make a separate pocket for storage of other accessories like eartips. Plus, it comes with a twin-tube double sleeve (in red) to separate earpieces so you can keep them apart and secure during transportation. Though I do like VanNuys storage case, it is not exactly pocket friendly.


Other included accessories are a set of S/M/L regular wide bore silicone eartips, a set of M size double-flange eartips, and a set of S/M foam eartips. You will also find a cleaning tool, and a removable cable shirt clip, though the spring-loaded mechanism to attach to the cable won’t work with the included thick PWA cable. I assume this cable clip is a standard stock accessory for use with thinner cables.

Overall, the packaging and accessories are practical, but at this price the unboxing lacks a wow-factor.



The stock cable is a customized version of a popular PWA (Peter Wong Audio) 1960 4-wire (8conductors) cable which retails for over $2.2k by itself. As I mentioned in my EE Odin review where they also used PWA 1960, these cables are quite popular and in demand even considering their premium price.

The cable uses 26AWG gauge wires and FEP jacket for a positive signal (as part of the core) and 24AWG gauge thicker wires and PVC jacket for a negative signal (as part of the shielding). The wires are insulated and combined under a tightly braided black carbon fiber sleeving which has a nice touch and still feels very flexible. Don’t expect a see-through jacket which showcases the wire. This cable is not about pretty looks but performance and isolation, using UPOCC Litz Copper premium wires presumably sourced from Cardas.

Since positive and negative signal wires are combined under the same sleeve inside of a coax cable design, you can only see two Left and two Right wires, thus a name of 4-wire cable, but you have a total of 8 separate conductors, 4 on each side. The cable comes with a brand name genuine Pentaconn 4.4mm plug, carbon fiber black y-split, and PWA signature wooden round chin slider designed to minimize microphonics effect. Toward the connectors you have a flexible clear heat-shrink earhook going into PWA 2pin connectors with red/black ring marking and red/black short strain relief to indicate Right/Left sides.



Before I go into the design details, I want to point something out. Often, people make assumptions that a flagship IEM should have a fancy look. If you Google “Traillii” you will see that it is a type of a small flycatcher bird that looks rather plain from outside, until it starts to sing. As Wikipedia says “… their song is the only reliable method to tell them apart in the field” from other similar birds. That pretty much describes how I felt about Traillii when I put these small shells in my ears and let them sing! Don’t know if this is what Oriolus guys had in mind, but it sure does make sense to me. While Traillii doesn’t look as flashy, once you hit Play you will hear a BIG sound.

The IEM itself has a 12driver design with a 3-way crossover that partitions drivers into 2BAs for lows, 6BAs for mids, and 4ESTs for highs. And despite 8BAs and quad ESTs along with voltage transformers, everything is squeezed inside of a very compact clear shell with a unique brownish/reddish faceplate finish covered in hairlines of fiber strands. Oriolus also offers a selection of 36 alternative custom faceplates, but they do have a warning it will delay availability of Traillii if you decide to customize it.


What is interesting, despite packing a more advanced hybrid design config inside, Traillii shells are nearly the same, and maybe even a touch smaller than all-BA Mellianus. The body of the shell is made using Photopolymer material, and as I already mentioned, the shell design is very compact with a transparent body and standard universal faceplate selection which can be customized. The nozzle is a bit thick and shorter, has a secure lip at the top, and has one large bore opening and 3 smaller ones. Also, 2pin socket is recessed, just like in Mellianus.


The fit was very comfortable and secure with stock eartips, and with shells being so lightweight I didn’t even feel them in my ears. I do know that some people prefer CIEMs, but I’m not aware if one is available for Traillii.

The fit.


Sound Analysis.

I analyzed Traillii paired up with LPGT while playing a variety of test tracks, such as Agnes Obel “The curse”, Sandro Cavazza “So much better” (Avicii remix), C-Bool “Never go away”, Ed Sheeran “Shape of you”, Alan Walker “Darkside”, Galantis “Hunter”, Iggy Azalea “Black widow”, Indila “Boite en argent”, Dua Lipa “Love again”, Counting Crows “Big yellow taxi”, David Elias “Vision of her”, and Michael Jackson “Dirty Diana”.

To my ears, Traillii has a big open sound typical of full-size dynamic driver headphones with nearly a holographic soundstage expansion. The soundstage and the imaging are the first things that stands out when you start listening, feeling like you are right in the middle surrounded by the sound, able to pin-point and "touch" every single element in space due to a rather accurate and realistic placement of instruments and vocals. And thanks to a very good layering and separation of the elements in 3D space, every sound, every nuance is easy to distinguish and to focus on.

I usually don't start my sound analysis with soundstage description or the talk about layering and separation. But since I did, some could probably assume that Traillii might have a more reference quality analytical sound. After getting over the initial soundstage impression, you realize the tonality is very natural, with a full body organic sound which at the same time has a rather good level of detail retrieval approaching nearly a micro-detail level, not a typical combination for IEMs which don’t have analytical tuning. We are talking about a natural tuning with a balanced W-shaped signature where the bass, mids, and highs stand out in their own domain and blend in a coherent harmony.

To break it down further, each bass note is weighted with a deep textured sub-bass rumble and tighter dynamic-driver quality mid-bass punch. During my listening sessions, quite a few times my brain got tricked into thinking I'm listening to a dynamic driver bass performance even though Traillii has 2BAs to cover low end. The bass was so visceral and hitting with such well-articulated authority that for a second, I felt like I was listening to a powerful dynamic driver. But at the same time, while bass is powerful and elevated, it is not overwhelming to a point where it overpowers the mix. The bass is there, it hits hard with authority and control, and it does feel like DD performance with a little slower attack and longer decay but without spilling into lower mids. This is not L-shaped tuning, it is W-shaped, though I still think it will satisfy equally bassheads and audiophiles with a basshead fetish, but stay clear if you want a more neutral bass.

Mids are very natural, soulful, organic, and at the same time quite detailed and layered. Lower mids are above neutral, giving a fuller body to the sound and also helping bass to blend in more naturally with upper mids. It has just the right amount of quantity and tuning quality to make sure the overall sound is not muddy or veiled considering the organic nature of the tuning. Upper mids are very detailed, I rare combination of being close to micro-detailed level without being cold and analytical. Vocals sound very natural and realistic as well, regardless if it is male or female. And again, after the extended listening I almost forgot that these are BA drivers because of the organic texture of the sound which is more typical of DD performance.

Treble has a very natural balance of clarity and airiness, excellent extension, and a well control sparkle without a hint of harshness. It was hard to believe there are 4xEST drivers because the tonality of the treble was so natural, so well defined and well controlled without any harshness or sibilance, and yet fine-tuned to be extended, super clear, and well balanced with the rest of the frequency spectrum. For me personally, Traillii treble tuning really hit the sweet spot because I’m really picky about the treble and harsh upper frequencies drive me nuts.

The two things that really stood out for me was a natural holographic soundstage and the coherency of the 12-driver hybrid tuning where BA-bass, BA-mids, and EST-treble were in a perfect harmony, sounding like full size open headphones with one large dynamic driver. And also, I was impressed how well the sound tuning scaled up at low and high levels of volume. With some IEMs raising the volume up brings mids more forward, or while listening at lower volume pushes mids back and brings up bass more forward. Here, the relative tuning balance stayed intact as I was varying the volume up and down.


Eartips selection.

The selection of eartips is crucial with any universal in-ear monitor and will affect the sound, especially the bass impact depending on the seal and the soundstage depending on insertion depth. Due to a large opening of my earcanals, I usually go for the largest size eartips to get a better seal. Please, keep in mind, these impressions are subjective and relative to my ear anatomy which affects how I hear the sound.

Stock silicone tips - gives sound the best balance between lows, mids, treble; my baseline natural detailed tonality.

AZLA Sedna - adds more sub-bass rumble and lifts mid-bass higher, great if you want even more bass impact.

JVC Spiral dot (original) - these shrink the soundstage a little bit; soundstage is still wide but not as wide which loses the holographic effect.

Final Type E - the narrow bore opening here messed up the sound, vocals became congested and a bit muddy and soundstage was narrow.

Symbio F - was surprised how well these fit Traillii thick nozzle; and found a very interesting effect of bass being a little attenuated, especially sub-bass, while mids/vocals being a little brighter, more forward, and more transparent.

SpinFit - similar to Symbio F, bass has a little less sub-bass, bringing more focus to mid-bass, and vocals are a little brighter, more forward, and more transparent.

After I shipped out Traillii, I realized that I forgot to take pictures with various eartips.


The comparison was done using Traillii with a stock PWA cable, stock eartips, LPGT as a source (High Gain, balanced output), volume matched in every comparison. In this test I tried to compare Traillii to a handful of other premium IEMs with a specific premium cable in each pair up, noting a price of each combo so you can see that in some comparisons it is not too far off from Traillii price.

Traillii vs 64 Audio Fourte Noir w/EA Horus X - Both have a similar soundstage depth and height, but Traillii spreads even wider, making the sound more holographic. I specifically used Noir in this comparison because regular Fourte doesn't have as much body in mids, though you have to keep in mind that with Horus X cable Noir cost even more than Traillii. Here, the overall signature and tonality are very close, especially when I use Noir with foam eartips to tame down the treble sparkle. Both have a balanced W-shaped signature with a fuller body more natural tonality. And 2BA Traillii bass has an even deeper sub-bass rumble than DD Noir. Treble of 4EST Traillii matches very nicely with TIA Noir, but I did have to use foam tips with Noir. Mids is where they vary and it is quite noticeable. While both have a natural organic tonality, the presentation is different with Noir mids being pushed a little more back, more confined (narrower), more colored and thicker, and by far not as layered or separated as in Traillii where mids are more detailed, more layered, a little more transparent and more expanded in width. Fourte Noir with EA Horus X cable retails for $6.3k.


Traillii vs 64 Audio A18s M15 w/Eletech Iliad - Here, the soundstage depth/height is quite similar, but the width is different with Traillii being wider, creating more holographic effect while A18s being more focused and a little more intimate in soundstage presentation (tuned for studio and stage performing artists). In this pair up I picked A18s instead of U18t since A18s is a better match for comparison with its fuller body more organic tuning. When it comes to bass, both have a very similar mid-bass punch, but Traillii has a deeper and more textured sub-bass rumble; A18s sub-bass extension is no slouch either, but Traillii just has more quantity and more weight in sub-bass. Mids are actually quite similar in this comparison, with fuller body lower mids and natural detailed tonality of upper mids/vocals, though technically Traillii has better layering and separation of sounds in mids. Both have a natural well-defined treble without any harsh peaks, but Traillii has more sparkle and airiness in comparison to smoother treble extension in A18s. A18s with Eletech Iliad cable retails for $4.8k.


Traillii vs VE Elysium w/EA Code 51 - This was another interesting comparison, and to start off, the soundstage expansion in width/depth/height is actually quite similar here; maybe with Traillii expanding a touch wider but it is a minor difference. When it comes to bass, Ely can get you deep and with a nice punch, but it is scaled down when compared to Traillii. Ely bass has rumble and well controlled BA bass, but Traillii sub-bass rumble and texture is on a whole different higher level of quantity, hitting harder and with more visceral authority. Now, here comes the best part of the comparison. I always hold Ely Dynamic Driver mids in a very high regard, and Traillii mids sound very close to Ely's, which goes back to my sound analysis where I felt like I was listening to DD driver. Traillii mids/vocals actually sound a little smoother and a touch more organic but this is due to a difference in treble. I know, we are comparing 2EST (Ely) vs 4EST (Traillii), but the tuning of Ely treble is brighter, more vivid, crisper, while Traillii treble has better control with a more natural revealing tonality which is not as vivid. Elysium with EA Code 51 cable retails for $5.2k.


Traillii vs FIR Audio M5 w/1960 4wire (w/2pin-mmcx adapter) - Both have a similar soundstage depth/height, while Traillii spreads wider, giving it more 3D holographic spacing. Also, both share a very similar mid-bass impact typical of a dynamic driver where M5 lows are actually covered by a dynamic driver while Traillii got BAs pushing the bass. But when it comes to sub-bass, Traillii still goes deeper with more elevated textured sub-bass rumble that surpasses DD here. Mids in Traillii have a fuller lower body, giving mids/vocals more organic warmer tonality in comparison to M5 having lower mids a little south of neutral, still above neutral but a little thinner in comparison. Both have very detailed layered upper mids, but the fuller body of Traillii gives vocals more natural organic tonality. Also, the presentation of mids/vocals is a little more forward in Traillii, while slightly pushed back in M5. Treble response is very close between these two, both are well controlled, natural, and airy, but Traillii is a little smoother in comparison. M5 with PWA 1960 4wire cable retails for $4.8k.


Traillii vs EE Odin w/1960 2wire - Finally, we have a soundstage match with a nearly identical width/depth/height 3D holographic expansion. But other than that, there are quite a few differences in tuning. Odin has double DD bass but it wasn't tuned with the same impact and depth as their Legend X, and that is where Traillii has the advantage if you are craving deeper rumble and more authorative impact. In a way, Traillii takes Odin bass and scales it up in quantity across sub-bass and mid-bass. In mids comparison, Traillii has noticeably fuller lower mids, adding a lot more natural body to the sound, to the vocals, while in comparison Odin has more neutral body. Upper mids are more micro-detailed and with a more precise analytical layering and separation of the sounds in Odin, while Traillii has a more natural more organic tonality of upper mids with a very good layering and separation but not with the same surgical precision as Odin. Treble also follows the same direction, being brighter and crisper in Odin and more tamed and natural in Traillii. Both have next gen quad EST drivers covering the treble, but Odin follows a tuning theme of a more revealing micro detailed sound while Traillii gives you a fuller body more natural sound while still reaching for micro-detailed technical performance. Odin with PWA 1960 2wire cable retails for $3.4k.


Traillii vs Oriolus Mellianus w/PS PPH8 - I know, Traillii little brother is not in the same league, but I still wanted to give this comparison a shot after enhancing it with PPH8 cable. Mellianus comes with a premium silver cable and that pair up is smoother and more neutral, but PlusSound PPH8 expands the soundstage, improves retrieval of details, and improves the overall technical performance of Mellianus. Traillii still stretches the soundstage wider, even when I tried Mellianus with PWA cable. Mellianus bass has a good sub-bass extension with a rumble you can hear but it doesn't go as deep or has as much quantity as in Traillii. And the same with mid-bass punch, Mellianus is still closer to neutral, not exactly neutral (above it), but the punch of Mellianus bass doesn't have the same authority or articulation as Traillii. Both have natural detailed mids/vocals, but Traillii has fuller lower mids body which gives overall sound more natural coloring while Mellianus is relatively thinner and a little brighter in comparison. Surprisingly, treble has a lot of similarities, just a little smoother in Traillii. The big difference in this comparison are in quantity/quality of the bass and fuller body of lower mids in Traillii. Mellianus with PPH8 cable retails for $4.4k.


Traillii vs MMR Thummim – I don’t have Thummim with me at the current moment, but very recently spent some time with it, took lots of notes and measurements, so it is still fresh in my mind to compare with. Both have a wide holographic soundstage expansion, but due to a thicker sound of Thummim mids, in comparison the Traillii soundstage perception spreads a little wider, making the sound more open and expanded. Both have a powerful bass impact with a deep rumbling sub-bass and strong mid-bass, but Thummim sub-bass is more elevated, making its bass thicker, while in comparison Traillii mid-bass punches a little stronger with better articulation and more control due to a shorter decay of bass notes. Both have a fuller body lower mids, though Thummim is thicker and meatier with more recessed upper mids while Traillii adds just enough body to give the sound more organic tonality while still keeping it transparent, less colored, and with a better retrieval of details in upper mids/vocals. When it comes to treble, Thummim has more sparkle while Traillii is smoother and at the same time extends a little further. Thummim with its stock Plato cable retails for $4.5k, and those who prefer to pair it up with Eletech Iliad cable could bring up to $6.3k.

Traillii vs Vision Ears Erlkonig LBE (switch setting #2) - The first thing you notice in comparison is Erl being more sensitive, requiring me to lower the volume by about 12-13 clicks. Starting with soundstage, there are some noticeable differences. Traillii soundstage spreads wider left to right and has a little more depth with sound being just slightly more out of your head, placing you farther away, while Erl brings you closer to the sound and also slightly narrows down the left/right spread. As a result, Traillii gives you a more holographic soundstage presentation while Erl give you more intimacy, though both have excellent imaging with accurate placement of sounds in space. Both have a natural fuller body organic tonality, but when you start analyzing the sound closer, it is easy to spot differences. Both have a big bold bass with a deep sub-bass rumble, though Traillii has a little more lift in subs, while Erl has a little stronger punch in mid-bass. Upper frequencies vary with Traillii having a little more sparkle in lower treble, lifting upper frequencies with more natural definition in comparison to Erl being a little smoother. But when it comes to treble extension, Erl's treble goes further and has a little more air in upper treble. The biggest difference is in lower mids. The bass and the treble difference are something you need to focus in order to spot it, with lower mids it is clear from the moment you start listening and comparing. Erl's lower mids are thicker with more body, giving overall mids and vocals a smoother fuller body organic tonality. Traillii lower mids are a little leaner, still having a full body but it is leaner in comparison to Erl, which makes Traillii upper mids and vocals to sound more revealing and more transparent (less colored). But overall, both have detailed resolving natural tonality mids. I didn’t go through cable rolling, Erl used in this comparison ($5k retail price for Limited Black Edition) had its stock pure silver cable, and as many are aware, Erlkonig has been discontinued and completely sold out.


Source Pair up.

With Sensitivity of 112 dB and Impedance of 21 ohms, Traillii is very easy to drive and has a great hiss-free pair up with many sources. In some pair ups it needed a few extra clicks of volume, but nothing too extreme.

Lotoo PAW Gold LPGT - holographic soundstage expansion, balanced W-shaped signature, very natural fuller body detailed tonality. Deep sub-bass rumble, authorative visceral well controlled bass punch, natural organic layered mids/vocals, and well defined airy treble extension.

A&K SP2000 SS w/AKA 4.4mm adapter - nearly identical to LPGT, just will a little more sub-bass rumble and slightly warmer upper mids.

iBasso DX220 MAX - I would say this pair up takes Traillii performance to the "MAX". The soundstage is still holographic, but I hear the bass being tighter and more articulate, with cleaner blacker edges, mids/vocals still being natural and detail, but now even more resolving and more layered, and treble has a little more sparkle and airiness relative to LPGT.

Hiby R8 (w/Turbo) - nearly identical to LPGT, just with a little more sub-bass rumble and slightly warmer upper mids, similar changes as I heard paired up with SP2k SS.

L&P P6 - very similar to LPGT with a natural detailed tonality, but the sub-bass tickles you with more rumble, going even deeper. Also, mids/vocals are a little smoother and more organic which affects layering and separation a little bit, but also makes the sound more musical and even more natural.

Cayin N6ii w/E02 - another "variation" of LPGT pair up, but with N6ii I hear an even deeper, more textured, more velvety sub-bass rumble, making bass sound like a floor standing speaker. Plus, I also noticed that treble is a little smoother here, less sparkle; still well defined but just a little less sparkle and airiness.



As I started to write Conclusion to this review, Traillii was already on its way to another lucky listener waiting to audition these IEMs, and as you can probably sense, I miss them and looking forward to borrow again. I heard and reviewed many different flagships and usually very neutral and restrained without any overhyping emotions, but spending a week with Traillii was a different experience. It is almost misleading when you see a pair of small hybrid BA/EST iems, put them in your ears, and do a double take because you don’t expect such a big and bold sound.

Traillii is not exactly basshead tuned IEM, yet its double BA lows produce a powerful authorative bass slam and a deep sub-bass rumble you would expect from full size dynamic driver headphones driven by a proper desktop amp or from hha floor-standing speaker. Its mids are smooth, natural, organic, with a full body sound that surprises you with a high level of detail retrieval and layering which is again atypical for BA driver performance. Its quad-EST highs are very natural and still airy and resolving. And on top of that you get a big holographic soundstage.

The price tag of Traillii will put these premium IEMs out of reach for many audiophiles, that is just a fact. But if you have a collection of high-end IEMs and cables, it is also a fact that you probably spend as much on your pair up combos as Traillii which comes with a special edition PWA 1960 4wire (8conductors) cable. And based on what I’m hearing after spending a week with Traillii, there are not too many other IEM/cable combos that match or overlap its performance. So, if you can afford it, give Oriolus Traillii a listen because its tuning is very addictive.
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with the cost of some of these iems, I think its fair to start comparing them to the darling full sized headphones like a Utopia or something. These prices are outrageous.
price aside (and i agree $6k is eyebrow-raising no doubt,) the real shocking moment is when you pop a pair of iems in your ears and they have a bigger soundstage than virtually every over the ear headphone you've heard, better layering, better bass, better treble, and an overall more engaging sound signature. not to mention that they're easily driven out of your iphone, and portable...if you dare to leave the house with them in your ears...
Pros: Endgame performance
-Gigantic staging
-Compact housing for the spec
-Included with a flagship cable as default
-Quality accessories (case/earpiece holder)
Cons: Sky-rocketing retail price
-Must be purchased with a dedicated flagship cable

Oriolus Traillii Review - Absolute stunner

It is no surprise that the portable audio game is nowadays running to the extreme. The middle-priced products are making lesser appearance polarizing the price tag to either end of the spectrum, going completely affordable or completely premium. Well, our good old Oriolus had to get their ultimate flagship rolling out, featuring Oriolus Traillii.

Since Oriolus is a brand created upon the collaboration of CN and JP, until now most of their products have been divided into two variants, each being called CN version and JP version. The difference between these two versions was mainly found from the cable, as the JP version was usually equipped with a PW audio cable which also brought some price increase. Though this time, Oriolus has decided to release Traillii as the JP version only.

So how much does this product cost? Traillii is retailed for $6000, which is not only the most expensive product ever released from Oriolus but also one of the most expensivest earphone that exists to this date. This price is more than twice their previous flagship IEMs, which I would now like to lead to a question: is it worth it? Let us find that out.



Traillii comes in a simple if simple, solid if solid packaging. Other than the earphone, it includes a Van Nuys earphone case, Van Nuys earpiece divider, silicone eartips, and a cleaning tool. This sturdy case is large enough to store thicker custom cables and comes in very handy in usage. Along with that, the included IEM divider protects the earpieces from rolling around or bumping into each other. Barely any finesse has been done with the box but the included accessories are equipped with the highest quality. That is surely an aspect where I could detect the Japanese spirit.



The shape of the earpiece is very similar to one of their previous flagship models, Oriolus Mellianus, but actually a bit smaller and rounder in shape. The nozzles are rather a bit short and thick, but the dimensions are pretty much the same as other Oriolus IEMs and the fit is actually better with this one, so no need to worry about bumping into a fitting issue. Traillii is comprised of Sonion 8BA+4EST drivers which are distinguished apart from Oriolus Percivali which uses a DD+BA+EST combination. Oriolus has claimed that creating each earpiece is very challenging and often ends up to a faulty production as they have to house 12 drivers into an even smaller shell, also including two large voltage converter for the EST drivers.

Anywho, the nozzles are divided into 4 bores, each connecting the lows/mids/highs/tweeters. The bore for the lows is metal-tubed with the tweeter bores drilled to have a large semicircular shape. For the design, Traillii has a transparent body with an opaque crimson red faceplate highlighted with white fiber strands. Grading the design would be more up to personal preference, though I quite like the looks on these.



Believe it or leave it, a cable plays a major role in sound quality and an endgame earphone like this sure deserves an endgame cable. That is why Traillii is followed with HYLA's flagship cable Arthur RT-1 as the stock cable. Arthur RT-1 is an ultra high-purity OCC copper cable applied with additional shielding, planned by HYLA and produced by PW Audio.

The cable alone retails for roughly $2200, so you are getting the best of the best option as default without the need to seek for another cable. I suppose that makes the price sound lesser insane, at least some degree. It is also worth mentioning that the Arthur RT-1 cable used to be available in 3.5mm unbalanced only when purchased separately, but upon purchasing Traillii you get to decide the termination of your choice, varying between 2.5mm/3.5mm/4.4mm. Another interesting fact is that "Traillii" is the name that refers to this set of a combo, including both the earpieces and the cable.

So again, no CN version or any "cable-excluding" variants. This might come along to be a piece of sad news for some, though the more I test the stock cable and compare with other cables, the more I understood why they had to go for this cable. I own several other cables that are just as expensive as this, but none of them would bloom the sound beautifully and appropriately as Arthur RT-1 did. We will be covering detailed sound impression in the latter part of the review, but I suggest to maintain this original combo if you wish to enjoy the unique tone and reverbs that Traillii create.


Sound impressions - Lows

Although there is a good amount of full-BA IEMs with stellar bass reproduction, it still leaves me doubted about the bass performance when a company releases a full BA IEM. I was prepared not to be surprised and embraced with high expectations since the extreme price, I couldn't help but be amazed by the bass quality - the bass quality is too good on these. Traillii takes full advantage of controlling the tension and dynamics of the bass. Lows dive deep in a virtuous manner, making a calm and weighty punch that follows up with a fast and snappy decay. The extension and depth of the bass are outstanding - the bass drop nearly rings to the heart, which is not an exaggeration.

Lows are packed full of density and bass details as if an on-ear headphone has been pressurized into an earphone size at least. The bass lines are clear and highly thick in both size and concentration. The bass rumbles are clean, clear, and expansive. Perhaps the size of the bass exceeds the earpiece size, filling the lower end of the headroom with a full of dark bass presence and a pinch of reverbs. Just before letting any bassheads get hyped, I must note that Traillii is not a bass machine. Although these rumbles are deep, dark, and meaty, the bass punches are brought very calmly, softly, and precisely controlled in quantity.

Traillii focuses more on the latent energy of the bass rather than bursting it out in the face, having the sound to keep its posture and dignity. Along with that, Traillii seems to be paying much attention to keeping the atmosphere free of any stuffiness or overwhelming bass reverbs - which means that while the basslines and the imaging are massive, the slam of the bass is not exceptionally strong. Of course, the music does not sound light in bass as the depth and thickness are very plentiful and should be more than enough to satisfy most users.


Sound impressions - Mids

If the bass was already impressive, Mids are where you feel the true power of Traillii starts to shine. The imaging size for the vocal is massive, possibly one of the largest that in-ear monitors could produce to this date. Not swollen or loosen to sound bigger, but feels large in its original, unaltered state. Mids are up-close with blissful finesse on top with the outstanding texture and layering details. Mellianus is well known for its richness and beautifully articulated layerings, but Traillii takes them to another level, escalating the liveliness of the sound, near to a real-life level. Both male and female vocals perform equally well as they are.

Though I must mention that Traillii would open up its full potential once played with complicated tracks - so this "Traillii effect" would not be much effective on simple sounding tracks, such as solo ballad tracks. Possibly one of the very few cons Traillii would have, but this is something I would point out only if I have to insist on calling out a drawback. Other than that, the vocals are near flawless and show perfect stability throughout the range without any noticeable spikes and dips. Vocals would gradually spread its liveliness and openness even further as it approaches the upper mids. The sibilance area is smoothly finished and delivers a crispy bite instead of fatigues, allowing the listener to solely focus on the rich layerings.

The tone feels fresh and vivid but within the boundaries of keeping the sound natural and organic. The lower mids show a bit of a husky tone that is driven with force and power, which is another element that well mimics what a real-life human voice would sound like. Traillii is full of splendor, but it is done in a very natural and realistic manner that somewhat leaves you with a captivating "unconscious" impression - a kind of experience where you may think Traillii does not sound as stunning as expected, but then you get rear blasted once you go back using your old IEMs, finding them to be sounding boring or condensed.


Sound impressions - Highs, etc.

This is the part where EST drivers really kick in. Highs are full of air and the sparkling textures approach in a careful, soft manner. Its presence is just as vivid as other frequency ranges. But of course, it never gets overwhelming or breaks the harmony. The opened-up atmosphere powered by the airy trebles, the massive basslines, and the large vocal imaging. Pairing these three all together maximizes the staging and the headroom to a truly extensive level.

Speaking of treble, let us go for another short comparison between Traillii and the other two flagships from Oriolus - Mellianus and Percivalli. Incorporating Mellianus's splendid signature as the base sound, Traillii matured its EST performance once again beyond Percivalli. Highs are significantly more detailed with an up-lifting and fluffy presentation. While Percivalli had more of a straight-forward attitude in direction, Traillii is a lot more adaptable while having an even better resolution. Having enough rigidity to deliver sufficient crispiness, Traillii allows the treble to be flexible as demanded by different kinds of tracks. This makes the rigidity rather closer to Mellianus than Percivalli, but Traillii still provides a stronger impact/slam on the trebles whatsoever.



Traillii truly presents a monstrous sound and performance, but I still would not call it perfect. Not only the performance leap gradually decreases as you climb up the price range, but an eye-popping price tag of $6000 is more than enough to cross one's psychological "line of defense" for justifying the price. In fact, this psychological state greatly impacts the way how someone actually perceives the sound. It is a matter of answering the question of "can I accept this price to enjoy this level of sound", so if you are listening to this IEM with the pre-decision that you cannot/would not buy, there is a good chance of falling into a pit of bias. Even though I was used to dealing with flagship IEMs, the $6000 price tag has been bothering my listening session to be unbiased which I eventually got over it after a lengthy listening session and experience Traillii "as it is".

There is no doubt to call this an eye-opening experience in terms of sound. I remember someone commenting on Traillii for it to be sounding like Nerva-X, Percivali, and Mellianus combined all together. As someone who extensively listened to Percivalli and as an owner of Nerva-X and Mellianus, I do agree with that statement. If you are ready to spend some serious money and looking for one of the best earphones money could buy or for the ultimate Oriolus sound, Traillii is the one.


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Oriolus Traillii has been acquired by myself.
I am not affiliated with Oriolus and none of my words were modded or asked to be changed.


@szore , I've been an audiophile for years, maybe I'm having an ok boomer moment, but if someone has the resources, more power to them. Plus, their is an upside for we mortals, there is always “trickle-down, ” from advanced technology.
John Massaria
John Massaria
That’s a lot of loot for iem’s not gona lie - but thanks for review
I’ll stick with my Penon Orb


@ToddR P6 is a great DAP with Traillii. Both share a similar tuning trend, P6 can add some sweet tweaks to Traillii. The lower frequency to mids is going to be fuller, and even smoother. The treble is still on the smooth, natural side, not the top transparent combination, but the overall clarity still maintains world-class.