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Letshuoer S15 review : Not an S12 Successor

Shuoer has been making some highly praised IEMs in various price brackets. In the last few years we have seen the Tape and Tape Pro getting a lot of love from budget buyers. Their EJ07M, even after four years of inception has a lot of curiosity around it and the planar twins of S12 took the lower mid range IEM market by storm. They delivered some of the best technicalities and details and the value proposition was outstanding.

After an year of S12 pro Shuoer started teasing their passive radiator tech. The market had already seen the passive radiator tech. Single DD IEMs were able to extract very good performance and everyone was excited.

Within a couple of weeks we started seeing the S15. It looks nothing like the S12 but houses the same driver and an additional passive radiator to produce better clarity and definition. It has a lot of promises and a huge boot to fill. Available in only blue color S15 is priced at $329 which is nearly 2.5 times more than the OG S12 so.. The question is, how good this is, let’s find out.

get one from here:


S15 gives a premium unboxing experience. We get a dual layered box where the earpieces and some documents are placed in the upper half while everything else is placed in the lower half.

Pull the lower drawer and we are greeted by the connector plugs and the hard case. The cable and set of tips are placed inside it. We get one set of blue wide bore vocal tips and another set of smoked narrow bore balanced tips. A cable tie concludes the list of accessories out of the box.


This is the same cable we got with the S12 twins. It has exactly same cores with modular connectors. Unlike most IEMs we get a dual core with 216 strands of SPC wires inside them. I like the looks of this cable and the thicker cores mean it can stand some abuse and yanks without any issues. Thanks to the thicker cores this cable barely tangles but that also make it slightly less supple but it barely has any annoying memory issues to worry about. It does not hold shape but changing its shape is not easy. There isn’t much microphonics to worry about but it’s not the most silent cable, thankfully this isn’t a bouncy, which is a good thing.

Thanks to its premium positioning we get 3 modular plugs and they look premium. The build quality of the parts is very good. We get light weight metal jackets on the Y splitter and 2pin connectors while the modular plugs have half metal and half resin like plastic. Cable guides are not aggressive and don’t exert much pressure on the ears.


Unlike the S12 twins we do not have the luxury of metal shell. What we have is an acrylic shell that is lighter and more comfortable inside the ear. Shuoer doesn’t like to make semi custom shell and this IEM is no exception either. S15 has a nicely curvy design but doesn’t have any wing structure to provide more traction inside the ear but the rubbery texture on the shell helps a lot. It is very comfortable inside the ear, unlike the MP145 which is bigger and oddly shaped. There are two air vents for the shell to breathe. We get an aluminum-magnesium alloy back plate which looks different and distinct but polarizing too. Thee internal design is more interesting though. It has a 6mm R-Sonic passive driver placed aside the planar.

Few lines about this 6mm R-Sonic driver from Letshuoer:

“LETSHUOER S15 adds a 6mm passive filtering module outside the planar driver.

The passive filtering module is LETSHUOER’s in-house R-Sonic Dynamic Harmonic Technology. Positive filtering of sound energy through proprietary filters”

Build with HayGears 3D printing tech it is very sturdy and solid to the hand. I am not sure if they have implemented any driver protection structure inside the shell but I don’t think this driver will be affected even if dropped on solid floor.


Unlike the S12 twins, pairing is not the deal breaker here. S15 doesn’t need a very powerful or desktop grade AMP to sound good but what if you have one? In that case S15 will deliver bigger stage, better layering and separation with more finishing definition and clarity. I paired the S15 with Q15 and it delivered accordingly.

Don’t pair this marginally energetic IEM with warm sounding sources or else things will be veiled and mushy. Pairing with a clean and clear sounding dongle or AMP will deliver better outcome.


Is this the successor to the S12 and S12 pro? Comparisons with the S12 twins are inevitable. We get a planar driver which is aided by a passive radiator which is supposed to help with enrichment of the lows and enhance accuracy. But S15 is totally different from what we get from the S12 and S12 pro. While those two were very V shaped, fun and energetic, S15 is calmer and more cohesive. It is more balanced with even emphasis across the spectrum but because of the slight pop to the vocals we get a W shaped signature.

It is neither dark nor warm, there is plenty of accuracy to favor any of these but we have a bit of crispiness and it’s nicely dampened at the same time, making it juicy yet fast. There is no extra energy with treble like the S12/pro so this sounds relatively calm and less aggressive.

I am using Fiio Q15 and stock tips for this review. I suggest using the vocal tips or any wide bore tips you have to add extra bit of juiciness. It sounds much better.


To start the S12 twins are less dynamic and can get boomy while lacking control and definition. First thing that the S15 improves on is the technical ability. Sub-bass is nicely deep with very good rumble but doesn’t have the wooly feel. Mid bass is a bit forward and fuller with very good body and punch. It’s not as loose or heavy as the S12 and has much better definition and layered delivery. Area of impact is on the bigger side. It has a bit more weight as the centre but notes do not fade around the edge which is a good thing. Thanks to the adaptive decay speed this lower end is not overly soft or heavy. It lets the notes to precipitate only when needed. It hits upper bass notes cleanly, no extra slob behind them. This is the kind of control I like. S15 manages to deliver very good dynamics and definition without dialing the bass down.


Unlike the S12 this is not V shaped and that’s a big relief for me. We have a slightly W shaped signature because of the pop we get with vocals but the instruments around it aren’t lacking much energy. We get decent balance and very good clarity here. Macro details are super and the overall experience is high quality. But when we dive deeper, the whole mid range can feel like they are lacking a bit of substance. S12 twins were thin, but were not lacking resolution which the S15 has a bit less of. I do not have any issues with timber or tonality, they are aptly natural and organic. There is a bit of dryness which delivers crispy notes. Both male and female vocals are pleasant. They enjoy very good definition, accuracy and texture. I would have liked a bit more body behind male vocals but its fine.

Instruments are very good with attack and details. This attack isn’t soft but it isn’t sharp either, yet it can be both when needed. We get good energy and clarity and the finishing region. I just wish for the extra bit of details that we usually get with more technically capable IEMs.


This is where the S15 kind of feels lacking. People had a lot of expectations but the S15 can feel like it doesn’t have the attack and energy, resulting into lesser transparency but it will be wrong to say that the details are missing, all one has to do is pay a bit more attention. Yes, the micro details are harder to pick and the lack of resolution isn’t helping either.

It has decent energy and sparkle up till mid treble delivering good clarity with percussion instruments. It’s the upper treble that lacks the energy and compromising it’s engaging abilities. This lack of extra transparency makes it loose some points when it comes to clarity. It’s not that S15 is smooth or blunt. It’s actually is the lack of energy, slightly lacking resolution and sharpness in the upper treble region are letting the S15 down. Extension though is just par. I doesn’t compete with even the S12 twins here.

Layering and separation are very good. We get fairly accurate and well defined instrument placement. Air is very good but the lack of energy up top makes the notes sound less clean.


This is where the S15 excels. It has a much bigger stage than most IEMs in this price. We get a well expanded, nicely rounded stage which has very good height, width and depth giving it a more 3D like imaging. I like the way it places instruments around the head, both in front and back, up and down of the head, giving it an edge with imaging and accuracy too. Sonics are very good. Its contrast of back and foreground instruments is high quality and the movements of instruments are clean.


vs Dunu Falcon Ultra:

vs Hidizs MP145:


Why should you buy the S15? Buy it for the calm and control it has while delivering pleasing tonality, timber and texture without being sharp or thin anywhere in the spectrum. I am impressed with its balance and accuracy up till the mid treble region. It balances everything exceptionally well. There is no aggression to bother or warmth to make things mushy. Yes, it lacks a bit of resolution and some micro details too but then people are happy with Sennheiser IE900 which lacks a lot of resolution, when compared to that, S15 is miles ahead.

Don’t buy this if you want a V shaped IEM that has plenty to bite or aggression. This is not for you if you want the best details and resolution for the price. S12 twins are not replaced by S15 and if you need an upgrade to them, look at the EJ07M.

If you have any questions feel free to drop a comment.

Enjoy your music and cheers!!



Picture of Suman Sourav Meher

Suman Sourav Meher

My humble audiophile journey started in 2010, when I was in college, where I fell in love with the elements, nuances, and variations of this mesmerizing world. The ability of tiny earphones to recreate amazing sounds made my bad days tolerable and good days better! Now I am a full-time audiophile with a preference for musical tracks, especially vocals and engaging ones. I must admit I am addicted, but not to drugs or alcohol, but to earphones. Come join me as I share my experiences, bad or good, and let’s have some fun!


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