The S12 Pro and S12 Ultra are essentially different versions of the same 14.8mm single-driver planar magnetic IEM. The Ultra is the latest model, priced at 169 USD, while the S12 Pro is slightly less expensive.
The S12 line began with the S12 in 2021, followed by the S12 Pro in 2022. In response to customer feedback that the treble was slightly hot, Letshuoer released the S12 2024 Limited Edition, and in 2025 they introduced the S12 Ultra.
Both IEMs have nearly identical housings, but their colors differ. The S12 Pro is blue with silver details, while the S12 Ultra comes in mocha or gunmetal gray. The S12 Ultra comes with a small USB DAC/AMP dongle.
My full reviews can be found here:
- S12 Pro Review
- S12 Ultra Review
SOME WORDS ABOUT AMPLIFICATION
The S12 Pro can be quite sensitive to amplifier matching, and I remember from my S12 Pro review that some amps could tame the treble and deliver excellent results.
I didn’t find that kind of synergy with any of my portable options, but I do recall the Sparkos Labs Gemini tube hybrid amplifier transforming it into a truly fabulous earphone. This isn’t a setup most people would go for, but it’s worth noting that if you’ve already found a perfect synergy for your S12 Pro, you might not be as enthusiastic about the new version as others.
LETSHUOER S12 PRO SPECIFICATIONS
- Driver: 14.8mm planar-magnetic driver
- Impedance: 16 Ohms
- Sensitivity: 102dB
- Frequency Response: 20Hz – 20KHz
- Cable：1.2 m Silver-plated copper
- Cable Connector IEM: 0.78 dual pin
- Cable termination: 2.5mm / 3.5mm / 4.4mm swappable
- Shell material: Aluminum alloy
- Faux leather carrying case
Current price and availability:
LETSHUOER S12 ULTRA SPECIFICATIONS
- Driver: 14.8mm planar magnetic
- Impedance: 16 ohms
- Sensitivity：101dB
- Frequency Response：20Hz – 40kHz
- Cable：1.2 m Silver-plated copper
- Cable Connector IEM: 0.78 dual pin
- Cable termination: 3.5mm / 4.4mm swappable
- Shell material: Aluminum alloy
- Included DT01 USB dongle (3.5 mm output)
- Puck shaped storage box
Current price and availability:
LISTENING COMPARISONS
Associated equipment:
- Amplifier: Topping A90
- DAC: RME ADI-2 DAC FS
Sugar Craft by Medeski, Martin, and Wood
Both sound great and they’re very similar. The S12 Pro a tad crisper, the S12 Ultra a tad darker and smoother.
Bullet in The Head by Rage Against the Machine
Also here they’re great and quite similar, but the Ultra feels cleaner and smoother.
Midnight City by M83
Here they’re more different. The S12 Pro has a splashiness on the percussion that’s not there with the S12 Ultra. The Ultra feels much smoother and more enjoyable. Except the treble, they sound very similar, though.
Sit Down Stand Up by Radiohead
The S12 Ultra has a smoother upper midrange and treble. It sounds more laid back than the more aggressive, crisper S12 Pro.
Walk it Back by The National
They’re very similar, the S12 Ultra might feel a bit smoother and thicker, but the differences are small.
Sunrise by Norah Jones
They’re a bit different here. The S12 Ultra is more laid back and smoother. The S12 Pro has a more upfront energy which I appreciate.
Like Suicide by Soundgarden
They’re very similar in the bass and lower mids. The S12 Pro has a crisper delivery in the upper frequency ranges, which certainly has an appeal. The S12 Ultra is less spicy – darker and warmer.
Never Enough by Loren Alred
This track can sound glary and harsh with many earphones. The S12 Ultra sounds pretty great, though – relatively speaking. There’s no excessive glariness. The S12 Pro has more upper-end energy and sound more glary shaper, crisper and dryer – in a bad way.
Young Vivaldi by Modo Antiquo
The S12 Pro has a nice energetic timbre, very upfront and crisp. The S12 Ultra is not miles apart but a bit smoother and darker, though still retaining a part of the crispiness.
WRAPPING IT UP
Sound Signature
They both have powerful bass and a relatively present midrange, but the Pro has a crisper more upfront upper midrange and definitely more spicy treble, the ultra is smoother and darker.
Treble
The treble is the main point of difference. S12 Pro has a more spicy, energetic and peaky high-end, which sometimes adds energy and attack to the music and other times becomes too much. The Ultra is smoother and less energetic in the highs. It’s like it’s EQ-ed down a bit, but it also sounds more refined – not as raw as the S12 Pro.
Midrange
The midrange can also be different depending on the track. The upper mid-range is more energetic with the S12 Pro, probably with the help of the crisper treble. The S12 Ultra sounds darker in comparison.
Bass
The bass is excellent and very similar on both earphones, serving as their main selling point. It is rich, textured, full-bodied, and detailed.
Soundstage and Imaging
The soundstage and imaging are quite similar between the two S12s, but it depends from track to track which is perceived as better.
Detail, Dynamics, and Timbre
The two earphones have generally similar levels of detail in the bass and mids. The S12 Ultra often sounds more nuanced and refined in the treble, especially on tracks where the S12 Pro can become too crisp or occasionally harsh.
Dynamics are generally very similar, but the S12 Pro has more dynamic range in the treble – which is part of its “problem”.
Timbre varies between the two, but to what extent depends on the track. On some tracks, they sound very similar, but overall the S12 Ultra comes across as darker and smoother, while the S12 Pro is crisper and more energetic.
CONCLUSION
It’s very clear that the S12 Pro and S12 Ultra share a lot of DNA and essentially use the same driver. On certain tracks, the differences are small, but they are generally consistent and easy to notice.
The S12 Pro has a crisper and more energetic treble, which can sometimes be appealing but can also be a bit too much depending on the track. The S12 Ultra is smoother and more laid-back, with mids that are slightly darker overall.
Even though the S12 Ultra is not always objectively better and the S12 Pro has its strong sides, I’m personally very enthusiastic about the new tuning. I think Letshuoer has done a great job refining an already great IEM.
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