Letshuoer S12 Ultra IEM Earphones Review – Addicted To Mocha Planar Might
Letshuoer S12 Ultra is a $169 USD pair of IEM In-Ear Monitors with a large 14.8mm Planar Driver at the core, and with a medium 101dB SPL and a low impedance of 16 OHMs, designed as an upgrade to the S12 line of IEMs Lethsuoer has been refining for a long time now. Today we review the new Shuoer S 12 Ultra and will also briefly compare it to the market and the other options you can find around the same price.
Introduction
After suffering one of the biggest rebranding of all times, from Shuoer to Letshuoer, the company is still at the top of audiophile choices when it comes to both affordable and high-end IEMS. Letshuoer actually makes the IEMs I use daily for gym, the Letshuoer Cadenza 12 2025, and they have released many popular models so far, having their products available on Aliexpress, Amazon, Linsoul and on their own Letshuoper shop as well.
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Product Link
Amazon – https://amzn.to/4nxQl1w
Aliexpress – https://s.click.aliexpress.com/e/_c3Cg6s4B
Build Quality – Design
Letshuoer S12 Ultra is designed around a large 14.8mm planar magnetic driver, a more unique approach for IEMs, as planar drivers need a large size to move sound, especially relative to the size needed by dynamic drivers. This being said, the company gave S12 Ultra an average SPL of 101 dB, so you might need to pump the volume a bit, but thanks to the low impedance you won’t have to stress too much, as S 12 Ultra has a low Z of just 16 OHMs.
For design, Letshuoer S12 Ultra inherits the same industrial approach of the S12 Line, with a re-engineered housing built around the female conductor. The cable has evolved to now be a 392-Core cable with a silver-plated, copper design, offering a reliable connection for S12 Ultra. In fact, this is a modular cable, and S12 Ultra comes with 6 pairs of eartips, but also with both 3.5mm and 4.4mm jack plugs for the cable, which is balanced by design. There’s a DAC included in the package too, and a transport case which is made of plastic.
You can see on the main page for S12 that it has a customized 14.8mm planar magnetic driver, and just like the original S12 and S12 Pro, it comes with a similar design and driver size, but Letshuoer promises improved tonality, wider soundstage and improved high-end extension with a punchier bass.
Fit – Subjective Usage
Letshuoer S12 Ultra is very comfortable, and the shell is made of metal, but fits well inside of my ears, shells feel natural, not too light, not too heavy, and their shape is very ergonomic. Although default eartips look very standard, they feel comfortable and are of a better quality than we usually get with entry-level IEMS.
S12 Ultra has a natural passive noise isolation of around 20 dB, and with music playing, even at low volumes, you shouldn’t notice the background noise. They also have an ergonomic cable that is fairly free from handling noise, and I love that the cable is ergonomic and you can even replace it if it breaks along the way.
Sound Quality
Pairings – To test the newly launched Letshuoer S-12 Ultra I have paired it with multiple sources including Rose Technics RT-5000, Dethonray Clarinet, iBasso DX340, Lotoo PAW GT2, FiiO K15, FiiO QX13, and Cayn RU9.
As dictated by the technical data, S12 Ultra is sensitive to source noise, and will change sonic character with said source quite a lot, as most IEMS with a low impedance do. This being said, it is also not very hard to drive and most dongle DAC AMPs will do just fine. The included dongle DAC AMP is decent, but to keep things fair for other IEMS, I have mostly powered S12U from my workstation reference DAC AMP which now is Luxsin X9, and also FiiO K17.
Overall Signature – Letshuoer S12 Ultra sounds sweet, and the first thing you notice is the sweet voicing and strong instrument separation, especially instrumental against voicing, where S12 Ultra not only is able to push both forward when needed but also defines each well, gives voices space to breathe, but renders instruments with the same sweetness and clarity as voices. It is quite interesting, it never sounds aggressive and too sharp despite revealing information and details well.
Bass – Starting at the base, Letshuoer S12 Ultra sounds warm and thick in the bass, with a large and slightly boomy bass. It renders a lot of weight and substance for instruments, gives music a spacious and big bottom-end. Bass extension climbs down to about 40 Hz, below which it rolls off gently. Most bass presence and punch is between 55 Hz and 200 Hz, as S12 Ultra has a bloomy, thick-ish presentation.
Midrange – With a sweet and fun vocal presentation, S12 Ultra gives music an organic, spacious presentation. Most voices are pushed in the forward layers, but so are most instruments, it doesn’t really push anything in the background or scatter music, and gives equal presence to male and female voices. While it imposes a somewhat thick and warm midrange, with a slightly flutter lower midrange, S12 Ultra paints a fairly clean image of how the recording / mix sounds like. For example, in the Memphis May Fire – Sinner, the vocal layer is pushed back, and s12 paints that well, while the master for Takanashi Kiara – Mirage pushes her voice forward a lot, and S12 Ultra renders that as well with precision.
Treble – As promised by Letshuoer, S12 Ultra has a better extension than S12 Pro and it climbs higher, up to 18 kHz, but with most energy around 9 kHz – 11 kHz, it does not sound particularly bright nor fatiguing. In fact, I feel like this is the most welcome change, as the original S12 and S12 PRO were both a bit more aggro in the treble, and the new S12 Ultra is more relaxed, more natural, more even and more balanced in the treble. It is a welcome change also because it allows air and effects, special synths to be more audible in pop and EDM, without forcing all music to be harsh, so SOAD and Infant Annihilator are still enjoyable as presented by S12 Ultra.
Dynamics And Textures – S12U has a natural dynamic range, there’s no compression, but it doesn’t present an ultra wide dynamic range. This allows music to sound different from album to album, from mix to mix, and keeps things interesting, allowing you to explore your library well. Textures are organic – juicy, with a wet character, there’s no trace of dryness or fatigue, and S12 Ultra renders details well.
Loudness Saturation Gradient – S12 Ultra sounds best at medium volumes, it can sound a bit too forward and with an increased THD at very high volumes, and the signature gets a bit more vague at lower volumes, but if I had to chose, I would most certainly say that medium is 1st place, low is 2nd and very high volumes is third place in how S12 Ultra handles sound. In fact, it seems to have a similar effect like planar magnetic headphones in particular with volume, very high can increase THD a bit.
Soundstage – Letshuoer increased the soundstage size with S12 Ultra, as it can render a wide, spacious sound, but still manage to push everything in the forward layer. This is achieved by having a very wide lateral staging, but with less depth. This kind of presentation works really well for EDM, Dubstep, Pop and modern music, and can push violins and pianos to unexpected places, but it is best for modern music and pop in general.
Value and Conclusion
Letshuoer made sure to price their S 12 U IEMs with a low price, but include accessories that would cost the price of the IEM if sold alone, like the modular cable, but they also launched an evolution from their S12 Pro, delivering a new, thicker, warmer sound, more air, all for a good price.
At the end of the day, if you’re looking for a natural sounding pair of IEMS with an organic midrange, exceptionally sweet voicing, ergonomic fitting, and with an airy treble, modular cable and with a DAC AMP included in the box, Letshuoer S12 Ultra is an excellent choice, and shows nicely how the company went from having a bright and somewhat unnatural midrange to having a really natural and clean signature, that will be pleasing for all listeners to come.
PROs
- Modular cable
- Ergonomic shape and design
- Fairly good passive noise isolation
- Organic and sweet sounding midrange
- Deep and thick, warm bass
- Airy treble
- Resolution far above the price class
- Strong instrument separation and layering
- Wide and brilliant lateral dispersion
Cons
- Sensitive to source quality including source background noise and signature
- Transport case not the most reliable one, being made of plastic
- Not a deep sound
Product Link
Amazon – https://amzn.to/4nxQl1w
Aliexpress – https://s.click.aliexpress.com/e/_c3Cg6s4B
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Full Playlist used for this review
We listened to more songs than those named in this playlist, but those are excellent for identifying a sonic signature. I recommend trying most of the songs from this playlist, especially if you’re searching for new music! The playlists are different for Spotify, Tidal and Youtube, and based on the songs I enjoy and are available on each!
https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu
https://open.spotify.com/playlist/5J3oloz8Riy9LxEGenOjQ0?si=979ba4f082414be7
https://tidal.com/browse/playlist/330fd544-8e5b-4839-bd35-676b2edbb3d5
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