General Information

LETSHUOER S15: A Broader Soundscape

3rd Gen 14.8mm dual chamber planar magnetic driver + 6mm “R-Sonic” Passive Filtering Module​


14.8mm dual chamber planar +“R-Sonic”Passive Filtering Module

To achieve a more natural and comfortable sound transmission, LETSHUOER's research and development team combined the 14.8mm dual chamber planar magnetic driver with LETSHUOER's proprietary 'R-Sonic' PFM technology.


Dual Acoustic Tubes

The dual acoustic tubes filter the sound on different frequency bands, allowing the highs, mids, and lows to shine through proportionately and seamlessly. Every detail is carefully tuned, presenting an excellent balance of audio quality.

HeyGears crafted shells

The S15, after thorough optimization of its chamber structure, strikes a perfect balance between form and function. In collaboration with the class-leading 3D printing company, HeyGears, the shell is lightweight and comfortable for long wearing sessions and has a matte finish that feels great.

The faceplate an aluminum-magnesium alloy CNC precision carved, sandblasted, and then anodized. It is resilient against scratch, smudge, and everyday use.

Quality interchangeable stock cable

S15 comes with a high-quality cable that is crafted from silver-plated monocrystalline copper which is minimizes degradation of signal integrity. It features a flush mounted 0.78mm dual-pin connector and has three 90-degree interchangeable connectors (2.5mm, 3.5mm, and 4.4mm). This accommodates various device interfaces, meeting most usage scenarios.

Six pairs of earbud tips and an exquisite storage case

The S15 comes equipped with two types of ear tips in three sizes, ensuring a tailored and comfortable wearing experience. The unique screw-on storage case has is well constructed, which securely houses all small accessory to maximize utility. This allows your earphones, ear tips, cables, and adaptors to be neatly organized within the case.


LETSHUOER S15 Specifications:

  • Model:S15 Wired In-Ear Monitor
  • Sensitivity:106dB
  • Frequency Response:20Hz〜40kHz
  • Impedance:30Ω
  • Chassis Material:3D printed resin
  • Cable:1.2m 216-strands silver-plated monocrystalline copper
  • Driver:14.8mm Planar Magnetic Driver + 6mm Passive Filtering Module

Latest reviews


New Head-Fier
Letshouer S15 : The Impressive Warm Planar
Pros: +Natural and organic
+Realistic timbre
+Exceptional bass
+Thick and lush mids
+Top imaging and layering
+Above average soundstage
+Modular cable
+Excellent build
Cons: +Price too much for many
+Definitely not for treblehead
+Design is not for everyone but quality is good

I recently had the pleasure of testing the Letshuoer S15, and I must say it left a lasting impression. As an avid audiophile, I'm always on the lookout for earphones that deliver a truly exceptional audio experience, and the S15 did not disappoint.

I would like to thank @LetShuoer Audio and Ivy for arranging a unit for me. My opinions are unbiased, and I haven't been influenced or instructed to praise these IEMs. Every detail in this review is actual experience made by listening for hours everyday.



The premium packaging comes with a high quality boxing with a slide out draw that holds three modular connector pins (2.5mm balanced, 3.5mm and 4.4mm balanced terminations) a cylinder containing an excellent modular cable. The two sets of silicone tips "Vocal ear tips" and "Balanced ear tips" The cable has an excellent quality and looks.

Comfort and Fit
Comfort is key during prolonged listening sessions, and the Letshuoer S15 excels in this aspect. The earphones come with a variety of ear tips, ensuring a snug fit for any ear shape. I found them comfortable even during extended use, making them suitable for daily commutes.


Sound Aspects

Source used :

Realme 9 Pro

Jcally AP7
Ibasso DC04 pro

This planar iems spend 50-60 hours of burn in before taking details of this review


The mid-bass it is forte, with quantity just enough when called. The quality of midbass is truly exceptional. The sub-bass is not the most extended, with a noticeable roll-off, resulting in no big rumble heard. It makes it up with solid texturing noted, with a punchy, fast and clean bass without any mid-bass bleed.

It has a more forward midrange and also a more thick note weight. Like the bass, sounds linear and clean, allowing you to literally enjoy the lushness of vocals and instrumental layers. The warm tonality of this iem removes all the negative quality of a planar transducer.


The highs is airy and resolving, it has great treble extension without being bright or sounding overly pushed to get fake air. As for the lower part of the treble, it sounds smooth and relaxed. Not dull by any means, just a forgiving and musical treble presentation. The transducer has less to no metallic timbre makes you have more time to listen to.

The soundstage is quite impressive. Giving the S15 an extra juice will produce the sound out of your head and above average in term of wideness and tallness.

The imaging and layering is above average. The sound layering is great making a holographic macro dynamic experience, but it feels a bit foggy in background when bass is produce or midrange instrument like vocal take the lead the wide presence of it will give a slightly blur definition edge of other instrument in similar range. With instrumental musical like classical, the imaging is impressive.


The Letshuoer S15 delivers a top-notch audio experience with its comfortable build and design and impressive sound quality. The enjoyment and time you spend with it will justify the price it cost. If you're in the market for high-end earphones that prioritize audio fidelity and for prolonged listening session, the Letshouer S15 is undoubtedly worth considering.


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New Head-Fier
Letshuoer S15 : The All Rounder Planar Set
Pros: Great build quality
Quite good isolation
Extra-nice packaging
Modular cable with angled connectors
Many nice quality tips
Macro & micro details
Note Thickness
Enchanched Soundstage
No driver flex
106 dB sensitivity = Quite easy to drive but better on balanced
Cons: Same Stiff cable and earhook ( could be better)
The price is "important/expensive" for many of us (hope to see some discount)
It could be too spicy for someone



The Letshuoer S15 was sent to me as a review sample from Ivy from Letshourer, for which I thank!

I am very happy to be able to try their latest model, especially because I had the chance to try the S12 Pro, which I liked a lot. In this new one, several things have changed. We have their new technology, which adopts a sort of passive radiator/filter and a 3D-printed shell.

This time the price becomes interesting, or rather important, so I will try to carefully evaluate all aspects.

However, the review will still be 100% honest and, in no way, biased.

I’m not an audiophile; I’m just a guy that likes to test out different IEMs and DACs and spends a lot of time listening to music.

So I’m not going to use super-technical words to review it, but I will do my best to describe it.

Tech Specs:​


  • Chassis Material: 3D printed resin
  • Material of Faceplate: Anodized aluminum
  • Frequency Response: 20Hz~40kHz
  • Impedance: 30Ω
  • Sensitivity: 106dB
  • Audio connectors: 2.5mm, 3.5mm, and 4.4mm interchangeable connectors
  • Cable: 1.2 m, 216-strand silver-plated monocrystalline copper
  • Driver: 14.8mm planar driver + 6mm passive filtering module


The packaging is exactly as I would have expected: very refined, elaborate, and pleasant to unbox. For a product in this price range, careful packaging is the minimum. You remove the external cardboard by sliding it and then, with a magnetic opening, you move on to its contents.


At first glance, we find a small letter with the warranty card, QC, and manual inside, which looks like a poster.

The accessories are in the drawer below, reminiscent of a jewelry box!

Inside, we find:

  • Hard case
  • Modular cable with 3 adapters 2.5mm, 3.5mm, and 4.4mm adapters
  • 2 pairs of tips: Standard and Wide bore ear tips.

The included tips are of excellent quality; the wide-bore ones are spot on to improve the sound quality. Obviously, for such an expensive set, perhaps an extra set could have been useful; however, the ones included are the best possible. The cable is of the same material already seen on the S12 Pro and DZ4, and the fact that it is modular is excellent. I don’t doubt the quality of the cable but it is very rigid.

At the same time, it’s great because it doesn’t get tangled easily but it’s also a little uncomfortable in terms of comfort.

Design/Build quality:​

The Letshuoer S15 takes up the philosophy of the DZ4, and the materials are similar. The shell is 3D-printed resin by HeyGears, a well-known company in this sector. At first sight, you wouldn’t think it was 3D printed but with macro lenses, the layers are visible. The faceplate, on the other hand, is made of CNC-machined aluminum and the reason is probably the better resonance of the material. The construction is precise and well cared for, the dimensions are compact and the shape is comfortable. On the shell, we can see three ventilation holes.


Personally, I really liked the CNC-machined metal shell of the S12 PRO; same thing for the MP145 but Letshuoer has recently switched to producing shells with 3D printing. I’m not a sound engineer so I can’t tell you what’s best for the sound but certainly the S15, being made of resin, feels less cold in the ear. I know some are temperature sensitive and metal shell IEMs are downright cold in the winter.


Inside, we have reached the third generation of planar drivers, again 14.8mm but this time coupled with the R-sonic technology already seen on the DZ4, that is, the 6MM passive radiator/filter. I have read some complaints about it because its function as a passive radiator is not clear; in fact, it is more correct to talk about a passive filter. I’m not a sound expert or engineer, so it’s impossible for me to say whether this technology really works or not. To understand this, you should have a copy without this filter and compare them.



Its comfort is very similar to that of the S12Pro; on the inside, they are quite similar, in my opinion. I think that as planar IEMS, they are the most compact ever, very light, and comfortable. The tips also help a lot in terms of comfort. Very good insulation from external noise. The only sore point is the slightly stiff cable. For my taste, it is of excellent quality but if it were slightly softer, it would be perfect.

Instagram 360 Overview

Letshuoer S15 360 clip

Initial sound impression:​

The Planar Driver was a discovery for me. Maybe the first IEMs weren’t up to the level of headphones but now the GAP has decreased a lot.


The ones in my possession are the S12 Pro, Hidizs Mp145, Kefine Klanar and the Hifiman He400Se. The S15 is definitely an improvement over the S12 Pro and will automatically become one of my favorites alongside the Hidizs MP145. The others all sound extremely good, except for the KZ PR2. I haven’t yet had the opportunity to try planars that sound bad. Generally, the performances are truly remarkable, and the Hidizs MP145 have become a reference for planar IEMs. The S15s sound just as good but differently. From the first listen, the Letshuoer S15 performs extremely well in terms of details, layering, and a significantly improved soundstage compared to the previous ones. I carefully performed several hours of burn-in to try again once finished.

Final sound impression:​

Equipment used for the testing above


  • iMac
  • Redmi Note 7 Snapdragon
  • Poco M4 Pro Mediatek


  • Foobar2000 24bit 192kHz (iMac)
  • Amazon music UHD 24bit 96kHz (Both)
  • Tidal Hifi Plus


My impressions are given using just the original accessories.


Nowadays, planar IEMs do not require an excessive amount to sound correctly, but their properties are at their best with DACs with a certain power reserve. Often, the sound is more open, acquiring dynamism and sometimes a slightly different depth. The Letshuoer S15 has all the connectors, but asking a mid-range phone to drive them at their best is a bit much. My POCO M4 Pro performs quite well but lacks the right boost that a DAC can give on balanced output.

Thanks to HBB graph

Built in Technology:​

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.

R-Sonic Passive Filtering Module
To achieve a more natural and comfortable sound reproduction, LETSHUOER’s research and development team poured every ounce of their technical know-how into combining the 14.8mm dual chamber planar magnetic driver with LETSHUOER’s proprietary ‘R-Sonic’ PFM technology. Breaking through multiple technological barriers, the S15 is another outstanding entry into LETSHUOER’s planar earphone roaster, which delivers an unparalleled audio experience.
Dual Acoustic Tubes
The dual acoustic tubes filter the sound on different frequency bands, allowing the highs, mids, and lows to shine through proportionately and seamlessly. Every detail is carefully tuned, presenting an excellent balance of audio quality.
Letshuoer information

The introduction of this passive radiator called R-sonic has caused discussion. Initially, it was described as a passive radiator but in fact, it is more of a passive filter, which probably helps to eliminate the pressures that accumulate at slightly high volumes. In fact, like on the Hidizs MP145, you can raise the volume enough without feeling excessive pressure in the ear canal. However, I cannot be certain that the result I feel is not just due to the internal structure.

Best shot
The result obtained by Letshuoer is a planar IEM with a slightly warmer tone than the S12 Pro. I think this tone is more pleasant in general and suitable for a wider audience. Your favorite tracks are all enriched with macro and micro details. I don’t notice any problems of any kind except that you need tracks without imperfections; otherwise, you will notice those too. Although the bass is less high, I can confirm that it is felt more clearly and cleanly. The sub-bass is a little light.

Tips Rolling?​

The tips included with the Letshuoer S15 are practically the Nicehck 07 and the Whizzer SS20 (or very similar in design) so excluding cheaper models, I had the Dunu S&S and the Divinus Velvet to test. I am aware that upgrading the tips can have a lot of advantages for a planar IEM like this one.


  • The Divinus Velvets, as usual, prove to be universal; every headset you mount them on will give you the perfect seal and improved comfort. In terms of sound, I didn’t notice an exaggerated change.
  • The Dunu S&S, on the other hand, proved to be the tips that offer the greatest change—improved soundstage—but also the image seems to benefit. Surprisingly, there was no reduction in low frequencies; it was just slightly less comfortable.


Without a doubt superior to the S12 Pro, where perhaps they were slightly suppressed with the treble. However, with very clean and controlled bass, it completely envelops you with high-quality bass and gives a great sensation of depth. The graph shows a roll-off, but they seem like a nice, gentle sub-bass with just the right amount of rumble.

When listening to a bit of deep house or D&B, even if it lacks a bit of extra push, the quality of the bass and its thickness fully satisfy you. If the track requires it, the bass enters the scene in a decisive and auroritary way.


The midrange is fabulous, the voices and instruments are definitely in the foreground, and there is a warm note that gives depth to both. Stringed instruments have that warmth that gives them the thickness and reverberation of the strings in the air, as do the voices, which are vivid and silky. All were separated perfectly and accurately. The result is so beautiful that it adds musicality to each track. The bass remains well separated without covering the midrange, giving a very clear result. The tonality of both musical instruments and voices seems decidedly coherent and natural to me.


Finally, more refined and tolerable trebles even at high volumes. The S12 Pro seemed borderline to me, and when I turned up the volume, the treble region was very tiring in the long run. Here the highs, as you can also see graphically, are much more contained but the result is excellent; no detail or air is lost, in my opinion. Everything is more balanced and easier to interpret. Excellent amount of macro- and micro-details.

Soundstage and Imaging:​

The Letshuoer has a significantly improved soundstage compared to the previous ones. Sharpness and image have certainly improved, thanks to the new tuning, which allows all ranges to not overlap. The separation is at exceptional levels; all the musical instruments are correctly positioned and never confused. The general result is excellent performance, and its timbre adapts to any musical genre. I think it’s the most versatile IEM currently in my collection.


vs Letshuoer S12 Pro


Many still appreciate them and at the current price, who can blame them? Most people haven’t heard too much high-pitched sound like me, but actually, at human volumes, there are no problems. Obviously, I prefer the tuning of the new S15 and above all, the soundstage is significantly better. Their design, although very minimal, I liked more.



The Hifiman He400Ses are a miracle for what they cost; they sound decidedly flatter and more natural (typical Hifiman) but the dispersion of the sound they have must also be considered. Certainly, those who buy this model do not intend to be isolated from the outside.

Who win? Surely the Letshuoer S15 is definitely better but it also costs three times as much. The direct comparison is difficult but in my opinion, modern IEMs can easily compete with full-size headphones.

vs Hidizs MP145

MP145 Featured

The Hidizs MP145 for half the price, remains the queen of the scene when it comes to planar IEMs. I recommend you read the full review to get an idea.

The bass on these has an extremely particular impact, but the S15 beats them in terms of image clarity and perceived detail. Let’s be clear: we are not talking about day and night. They are both must-have models with different tunings and conceptions. Pay attention to the size of the Hidizs because not everyone finds them comfortable.

vs Kefine Klanar

Kefine Klanar Review: A Promising Start

Kefine is a new brand but I must admit that as their first product they have produced a successful planar IEM. The tuning is very warm and smooth so it will appeal to a wide audience. At the asking price it is certainly an option to take into account but if you are looking for something less relaxed you should at least switch to the MP145. If you don’t know them, I still recommend you read the review.



Finally, we come to the conclusion with my final thoughts. For my aesthetic taste, they are not the most beautiful on the market, but it is a detail I can ignore, as the most important thing is the sound. The market is increasingly saturated with proposals so standing out from the crowd is increasingly complex.

However, the aesthetic factor is often what triggers the customer’s desire to purchase a product. Here, I realize that not everyone might like it and many give a lot of importance to aesthetics, especially if you pay more than 300 USD.

Letshuoer has raised the level with the S15; its performance is very high, and even with the integrated technology, it is difficult to say whether it works or not.

Personally, I am of the opinion that when a certain sound level is reached, the sound undergoes a sort of change. I think the passive filter works better under a certain sound pressure. In any case, I’m not sure.

From my wallet point of view, a price under 300 USD would be decidedly more attractive and suitable for a wider audience.

Without a doubt, a fantastic set, with a decidedly high price (although it must be admitted that there are far more expensive things) and a tuning suitable for any musical genre.

Where to buy?​

LETSHUOER S15 Third Generation 14.8mm Planar Driver R-Sonic Passive Filtering Module Hifi Wired In Ear Monitor
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Reviewer at hxosplus
Pros: + Natural and balanced
+ Musical and addictive
+ Dynamic bass
+ Timbre realism
+ Smooth and polite
+ Lush and organic
+ Resolving and refined
+ Lightweight and comfortable
+ Well made
+ High quality modular cable
+ Accessories
Cons: - Treble is lacking in sparkle and excitement
- Transparency could be better
- Not made to impress
- Short length nozzles
- Shallow ear-tips
- Dull and unimpressive appearance
- Heavy competition
The S15 is the successor of the popular S12 PRO earphone. An updated version that features a third generation, 14.8mm planar dual chamber driver. To ensure smooth transitions between the octaves, LETSHUOER S15 employs a dual acoustic tube structure with filter crossover scheme. Furthermore, a 6mm passive filtering module outside the planar driver, which uses the in-house developed R-Sonic Dynamic Harmonic Technology, is used for positive filtering of sound energy through proprietary filters.

Non Audio stuff

The earshells of the S15 are made from a combination of 3D printed resin compound with CNC curved aluminum alloy faceplates. They are anatomically shaped and lightweight, offering a stable and very comfortable fit but the nozzle is too short so some of you might need double or triple flange ear-tips that are not included in the package.

Build quality is great but the appearance is rather dull, there is nothing attractive about it, the S15 is boring without the premium feeling to go along with the asking price.

The 1.2m long, 2-pin detachable cable is made from 216-strands of silver-plated monocrystalline copper. It is a modular design with interchangeable, 90⁰ angled plugs. The package includes 2.5mm, 3.5mm and 4.4mm plugs. This is a durable and well made cable with reinforced sheathing and minimal microphonic noise but it is rather thick and a little heavy.

The LETSHUOER S15 comes into a nice cardboard box with a bottom drawer that includes all the accessories. A water-resistant, rounded case made from plastic, two sets of ear-tips in three sizes each and the detachable cable along with the three plugs.


Audio stuff

With 30Ω impedance and 106dB of sensitivity, the S15 is rather easy to drive without needing special amplification. It scales well with some extra power and a competent USB DAC dongle will do the job perfectly fine. For this review I have mainly used the iBasso DC04PRO, Cayin RU-7 and FiiO M11S. As per usual practice, the LETSHUOER S15 was left playing music for about 80 hours before listening evaluation.

The LETSHUOER S15 is not made to impress with ultimate technicalities or some kind of a popular tuning. It is a balanced earphone with a fantastic and a bit laid back sound character that grows on you after a while to become an addition. Don't get fooled and start analyzing frequency response graphs, just close your eyes and immerse in your favorite music only to find out that the LETSHUOER S15 is extremely musical, engaging and natural sounding with special timbre realism. The music that reaches your ears is lifelike, harmonious and very colorful.

The bass is more than enough to offer great satisfaction with all kinds of music, from electronic to classical. Actually, the bass is masterfully tuned, it is mildly emphasized, not too prominent but not too linear either, it is tonally accurate and moreover it doesn't bleed into the mid-range or get muddy. This is a bass that sounds fun and critical at the same time. It is dynamic and impactful with good definition and layering. Tight, fast and controlled, full bodied, weighty and visceral without audible resonances. It might not be the most technical and transparent bass but it has a great sense of realism and power that competitive planar magnetic earphones will have a hard time to match.

The mid-range is present, harmonious and natural with just a little emphasis in the upper mids. There is no point in analyzing whether certain instruments or voices will stand at the front or the back of the mix. What matters the most is that everything is reproduced in a lifelike manner. Notes have plenty of weight and roundness around them, the S15 is resolving and refined with good clarity and definition. Instruments and voices are reproduced with realism, woodwinds sound like woodwinds, brass like brass and violins like violins, you get the point. This is an earphone able to extract all the diversity and the essence of the music making for a very addictive and unforgettable listening experience.

The treble is a great departure from the LETSHUOER S12 PRO with its mildly sharp and bright tuning. The treble on the S15 is toned down a little to make for a smoother, less edgy and more forgiving sound. This doesn't mean that the S15 is muted or short of extension and energy. This is not the most airy and luminous earphone but it is not lacking in either clarity and definition while it is very resolving. Detail retrieval is certainly good but this is not the most analytical and brilliant set of earphones. What really sets the S15 apart from some of the competition is the finesse of the texture as well as the naturalness of the timbre. Higher pitched instruments and voices sound weighty and full bodied without any kind of induced artificiality or metallic harshness.

The soundstage is wide and spacious with very satisfying separation and imaging. Nothing spectacular when it comes to depth layering or holography but still the presentation is grand and realistically proportional with a great sense of the ambience.


The LETSHUOER S15 are excellent sounding earphones with a very musical and engaging sound signature. With their latest earphones and namely their flagship, the Cadenza, and the entry level DZ4, LETSHUOER have proved that they are not afraid to break some eggs and part from the trend. Thankfully enough because together with the S15, they have made three excellent sounding earphones that combine solid technicalities with a great sense of musicality. Something difficult to find these days where most earphones are either trying to impress with stretched technicalities or are tuned using the same target curve that we are all supposed to like.

This is a very mature earphone made for listeners with trained ears who know to appreciate timbre realism and tonal balance more than anything else. The LETSHUOER S15 will make your music sound like real music again and become your daily addiction before you even know it.

The review sample was kindly provided free of charge.
A more comprehensive version of the review with selected comparisons is available in my website.
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