The Letshuoer S12 Ultra feels like the end of an era. After years of refining one of the most acclaimed planar IEM lines ever made, Letshuoer has taken everything it learned from the S12, S12 Pro, and S12 2024 Edition and distilled it into a final, mature form. As someone who has followed this series since its debut, I was both curious and nostalgic when I first plugged in the Ultra. Could this really be the definitive version-the “final call” of the S12 legacy? Let’s find out.
Letshuoer S12 Ultra
Inside the Box
The unboxing experience for the S12 Ultra stays faithful to Letshuoer’s minimalist aesthetic. The packaging is compact but classy, with a matte black box and gold accents. Inside, I found a generous assortment of accessories neatly organized:
- The IEMs themselves, available in Mocha or Gunmetal Gray color
- A modular 4-core silver-plated copper cable with both 3.5mm and 4.4mm plugs
- A DT01 Pro USB-C to 3.5mm dongle DAC
- Six pairs of ear tips (three “balanced” and three “vocal”)
- A round hard plastic carrying case with a threaded lid
The inclusion of a dongle DAC at this price is an unexpected bonus. Planar IEMs typically demand power to shine, and the DT01 Pro does a commendable job driving the S12 Ultra. It delivers a clean, clear, mid-focused sound, though pairing the Ultra with a more powerful DAC/amp brings out even greater depth and dynamics. Still, the fact that Letshuoer bundles a capable dongle makes this a true “ready to play” package.
Letshuoer S12 Ultra Accessories
Build Quality and Design
From the moment I picked them up, the S12 Ultra exuded craftsmanship. The shells are machined from solid aluminum alloy with an anodized matte finish that resists scratches and fingerprints. They’re smooth, lightweight, and feel built to last. The familiar teardrop-shaped housing of the S12 line remains, but Letshuoer has refined the design with slightly rounded edges and repositioned vents to improve airflow and tuning balance.
Each earpiece weighs about six grams-light enough for long sessions yet solid in hand. The nozzle length and angle provide a secure fit without pressure buildup, and the ergonomics feel dialed in perfectly. The dual venting system prevents driver flex and contributes to the open, relaxed presentation.
The new modular cable deserves special mention. It’s a soft, flexible four-wire braid with mocha-colored metal hardware that perfectly matches the IEMs. The screw-on modular plugs feel sturdy and secure-similar to DUNU’s Q-Lock system-and the strain relief is excellent. There’s also a working chin slider that stays in place during walks. It’s one of the nicest stock cables I’ve seen in this price range.
Overall, the design is understated yet elegant-no flashy patterns, just refined industrial simplicity. It’s unmistakably Letshuoer.
The Sound Experience
The S12 Ultra follows a warm-neutral tuning with a touch of sub-bass elevation and a slightly smoother treble compared to previous models. It feels like Letshuoer aimed to make the S12 sound more organic and musical without losing its planar speed or technical precision.
Bass
The low end immediately stands out as fuller and better extended than on earlier versions. The sub-bass has real rumble and texture, giving electronic music and film scores a satisfying foundation. Mid-bass remains well-controlled-punchy, not bloated-and transitions cleanly into the mids. There’s a richness to bass guitars and toms that makes the Ultra more engaging than the original S12, yet it never overwhelms the mix. It’s a slightly elevated but tasteful bass that favors warmth over slam.
Midrange
The midrange is the star of the S12 Ultra. Vocals sound lush and lifelike, with just enough warmth to convey emotion without becoming veiled. Male voices have excellent weight, while female vocals carry a natural sweetness free from sharpness. Acoustic instruments like piano, cello, and guitar exhibit realistic tone and body. Compared to the S12 2024 Edition, the Ultra’s mids feel a little denser and smoother-less analytical, more musical.
Planar IEMs sometimes suffer from thin mids or plasticky timbre, but the Ultra avoids that entirely. It’s one of the most natural-sounding planars I’ve heard under $200.
Treble
Treble is refined and easygoing. There’s enough sparkle to keep things lively, but the upper range avoids sibilance or glare. Hi-hats, cymbals, and violins are crisp yet controlled. The slight roll-off in the upper treble contributes to a smoother, fatigue-free experience, making the Ultra an excellent companion for long listening sessions. Listeners who prefer the ultra-bright, analytical character of older planars might find it a touch too relaxed, but for most ears, this is the perfect balance between detail and comfort.
Technical Performance
Resolution is strong, though not the highest in the planar class. What the S12 Ultra trades in raw microdetail, it gains in musical coherence. Imaging is accurate and stable, with well-defined placement of vocals and instruments. The soundstage is moderately wide and deep-more open than the original S12 but not as expansive as the S15. It presents a natural, three-dimensional image rather than an artificially stretched one.
Dynamics are smooth, not explosive. Macro-swings are satisfying, but micro-dynamics remain polite. This tuning emphasizes flow and balance rather than extreme contrast, and it works beautifully for most genres.
Power and Source Pairing
Like other planars, the S12 Ultra benefits from proper amplification. The included dongle drives it decently, but pairing it with a more powerful source like the iFi hip-dac 3 or DUNU DTC480 unlocks tighter bass, clearer layering, and more authority. Interestingly, it doesn’t change drastically across sources-it’s not overly source-sensitive-but extra current definitely helps it reach its full potential.
How It Compares
Letshuoer has iterated the S12 series several times, so it’s worth seeing where the Ultra fits among its siblings and competitors.
S12 (Original) – The one that started it all. Bright, energetic, and detailed, but occasionally sharp in the upper mids. The Ultra keeps the technical strengths while toning down the harshness.
S12 Pro – A touch cleaner and tighter, yet still somewhat forward in treble. The Ultra adds sub-bass weight and smoother upper frequencies, making it easier on the ears.
S12 2024 Edition – Many considered it the “perfect” balance of the line. The Ultra feels like a warmer, more laid-back version of that tuning, trading a bit of crispness for greater relaxation and musicality.
S08 – Another Letshuoer planar with a more dampened presentation. The S12 Ultra outperforms it in resolution, bass control, and overall refinement.
7Hz Timeless II and Hidizs MP145 – Competing planars in the same price bracket. The Timeless II is brighter and more analytical; the MP145 has a wider stage but heavier tonality. The S12 Ultra sits comfortably between them, achieving a blend of resolution and smoothness that makes it the most all-rounder of the three.
Who Will Love the S12 Ultra
The Letshuoer S12 Ultra is not trying to reinvent planar sound-it’s perfecting it for real-world listening. Its tonal balance and comfort make it ideal for:
- Listeners who enjoy neutral-warm tunings with deep, textured bass
- Fans of the S12 line seeking the most polished, fatigue-free version
- Those who appreciate planar speed but dislike metallic timbre
If you crave sparkling treble or exaggerated stage size, there are flashier choices out there. But if you want an effortlessly engaging, cohesive sound that works across every genre - from acoustic jazz to EDM to rock - the S12 Ultra delivers that with maturity and grace.
Final Thoughts
After spending weeks with the Letshuoer S12 Ultra, I can confidently say this is the most complete and balanced version of the S12 concept to date. It captures the spirit of the origina - its speed, clarity, and resolution - while fixing its tonal quirks and adding a new layer of refinement. The result is a sound that feels confident, natural, and deeply enjoyable.
Letshuoer didn’t just tweak the S12 one more time for the sake of it; they refined it into a timeless all-rounder that stands tall among planars under $200. Whether you’re new to planar IEMs or a long-time fan of the series, the S12 Ultra is a fitting finale-smooth, powerful, and beautifully built.
For me, it’s not just the “final call” of the S12 line; it’s the one that gets everything right.
Specifications
| Feature | Description |
|---|---|
| Driver | 14.8mm planar magnetic |
| Frequency Response | 20Hz–40kHz |
| Impedance | 16Ω |
| Sensitivity | 101dB |
| Material | CNC-milled aluminum alloy |
| Cable | 1.2m modular silver-plated copper (3.5mm & 4.4mm plugs) |
| Connector | 0.78mm 2-pin |
Verdict:
Letshuoer’s S12 Ultra closes the chapter on one of the most beloved planar IEM lines with style and finesse. It’s not a radical reinvention-it’s a masterful refinement. Warm, balanced, durable, and endlessly enjoyable, it’s a set I can recommend to almost anyone looking for high-end planar sound without the high-end price.
Where to Buy
You can find the Letshuoer S12 Ultra on:
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