The S12 Ultra is a single-driver planar magnetic IEM featuring a large 14.8 mm driver. It comes with the Letshuoer DT01 USB dongle and is priced at 169 USD / €145 pre tax.
MAIN TAKEAWAY
- Fantastic bass quality
- Smoother highs than the S12 Pro
- Nicely balanced tuning
- Excellent value
The S12 Ultra has a proud heritage. Letshuoer started with the S12 in 2021 and soon released an updated version, the highly successful S12 Pro in 2022. It became a reference among planar magnetic IEMs. However, some listeners found it a bit bright and wished for a slightly warmer tuning with a less aggressive treble.
Letshuoer first responded with the smaller S08 (8 mm driver), an excellent IEM featuring a smoother high end. Later they introduced a limited edition model of the S12 with a similar tuning, the S12 2024 Limited Edition. I really liked what they achieved with that version and found it odd that it was only a limited release. Fortunately, it seems they have now created a full production model with a warmer tuning — the S12 Ultra.
According to Letshuoer, the S12 Ultra has “extensively refined its internal construction”, making the 14.8 mm driver work more optimally than ever before.
LETSHUOER S12 ULTRA SPECIFICATIONS
- Driver: 14.8mm planar magnetic
- Impedance：16 ohms
- Sensitivity：101dB
- Frequency Response：20Hz – 40kHz
- Material: Aluminum alloy
- Cable：1.2 m Silver-plated copper
IN THE BOX
- 1.2 m cable with interchangeable jacks
- 3.5 mm and 4.4 mm jack
- Ear tips
- DT01 USB dongle (3.5 mm output)
- Puck shaped storage box
Current price and availability:
BUILD AND COMFORT
The housing has the same shape as the previous versions and is made of CNC-machined metal. It feels light, sturdy, and sits comfortably in my ears.
The cable is well-made, looks great, and has just the right amount of flexibility. It’s a 392-core silver-plated copper cable that uses 0.78 mm 2-pin connectors. The termination jack is interchangeable, and both 3.5 mm and 4.4 mm plugs are included.
There are also six pairs of silicone ear tips included, in two types (two colors) and three sizes each.
A more unusual accessory is the included USB DAC/AMP dongle, the Letshuoer DT01 Pro, which features a 3.5 mm output.
STANDALONE LISTENING IMPRESSIONS
Associated equipment:
- Amplifier: Topping A90
- DAC: RME ADI-2 DAC FS
Jambi by Tool
Guitars sound excellent—rich, warm, and textured. Vocals stand out clearly in the mix without any bothersome sibilance, which is often can be an issue with other IEMs. The bass is tight, textured, and full-bodied. The overall presentation leans slightly dark.
Smile by Pearl Jam
Smooth, detailed bass and snappy percussion. Vocals stand out in the mix, with little to no sibilance.
Almost Like The Blues by Leonard Cohen
Excellent bass that’s rich and textured. Vocals stand out with plenty of weight and nuance, and instrument separation is great.
Black Crow by Cassandra Wilson
Slightly dark with a very spacious character. Vocals are smooth and nuanced, the bass is punchy and full-bodied, and instrument separation very good.
As Before by Olga Konkova
Excellent punch from the cajón drum. The piano is crisp and clear, though slightly dark, and the vocals are smooth with a similar dark tone.
It Could Be Sweet by Portishead
The bass is fantastic—powerful, tight, detailed, and full-bodied at the same time. Vocals stand out nicely, smooth and slightly dark, though there’s some sibilance as is typical on this track.
Escape Route by Boris Blank
Again, the bass is fantastic—meaty, rich, and full of detail. Instrument separation is very good. There’s a hint of crispness in the upper registers that I didn’t notice on the previous tracks.
Spontaneous Compositorius by Thomas Agergard
The saxophone is smooth and slightly dark. The bright percussion is clear and clean, not overly sharp or harsh, but still has some zing that isn’t always pleasant—it rarely is on this track. The bass, as always, is excellent.
Maple Noise by Greene Serene
This is my favorite dynamic jazz improv, and the S12 Ultra did not disappoint. The bass is excellent, the percussion is very snappy, and the trumpet is smooth yet crisp. Instrument separation is very good.
Summer 3 Vivaldi Recomposed by Max Richter
Great instrument separation. Slightly dark instrument timbre.
Young Vivaldi by Modo Antiquo
Strings are smooth yet crisp, again the timbre is slightly dark.
Limit to Your Love by James
Vocals are smooth with a slight crispness. The bass is perfect—full-bodied and textured, well-balanced, powerful without being overwhelming.
WRAPPING IT UP
Sound Signature
The S12 Ultra has a powerful bass, slightly dark midrange, and relatively smooth yet slightly crisp highs.
Treble
The treble is not overly hot or harsh, but it’s not laid back. Detail level is excellent at this price point.
Midrange
The mids are detailed, nicely smooth and slightly dark sounding.
Bass
The bass is stunning. It’s powerful but not overpowering; it’s detailed and textured.
Soundstage and Imaging
The soundstage feels large for an IEM. Instrument separation is great, and the imaging excellent.
Detail, Dynamics, and Timbre
The detail level is generally very good, dynamics are powerful and tight. The timbre is slightly dark, slightly crisp, slightly smooth, and slightly dry – in a nice way.
COMPARISONS
Associated equipment:
- Amplifier: Topping A90
- DAC: RME ADI-2 DAC FS
LETSHUOER S12 PRO vs S12 ULTRA
The S12 Pro is the predecessor of S12 Ultra, and it’s clear that the S12 Pro and S12 Ultra share much of the same DNA – and driver.
While the differences can be subtle on some tracks, they’re generally consistent and easy to recognize. The S12 Pro has a crisper, more energetic treble that can be engaging but occasionally a bit too forward, depending on the track. The S12 Ultra, on the other hand, is smoother and more refined. The mids are generally a bit crisper with the S12 Pro, slightly darker on the Ultra.
Although the S12 Ultra isn’t always objectively better and the S12 Pro has its strengths, I’m personally very enthusiastic about the new tuning. Letshuoer has done an excellent job refining an already impressive IEM.
You can read my full comparison review here:
LETSHUOER S12 2024 vs S12 ULTRA
The S12 2024 is the Limited Edition version of the S12, released last year. I stated earlier that the S12 Pro is the Ultra’s predecessor, but it’s more accurate to say that it’s actually the S12 2024 that’s the predecessor, as the S12 2024 and the S12 Ultra sound so similar that they are mostly indistinguishable.
On some tracks, the S12 Ultra is slightly smoother in the treble and a bit darker overall, making it the smoothest and darkest S12 so far. However, the differences are very small, and I suspect there isn’t much between them — which, in my opinion, is a good thing. I really liked the 2024 version and wrote a very positive review of it, including several comparisons with other IEMs that would basically be identical for the S12 Ultra.
You can read my full S12 2024 review here:
Letshuoer S12 2024 Limited Edition Review
7Hz TIMELESS II vs S12 ULTRA
The 7Hz Timeless II is a single driver planar magnetic IEM with a 14.5 mm driver, very close to the 14.8 mm of the S12 Ultra. The Timeless mk1 and mk2 have been reference IEMs in their class, like the previous iterations of the S12.
Comparing the 7Hz Timeless II to the S12 Ultra , it’s clear that they share a lot in common. Their tonality is very similar: fantastic bass with a nice lift, darkish mids and clear highs. However, the Timeless II generally offers a slightly larger soundstage, a darker background, more subtle detail, and a bit better dynamics. In general the differences are not very large and they can often be hard to tell apart, but other times the differences are obvious.
You can read my full comparison review here:
Timeless II vs S12 Ultra Review
- Linsoul: 7hz Timeless II
- Amazon: 7hz Timeless II
AMPLIFICATION
So far in this review I have been using various desktop amplifiers, but for most users it is more relevant with the portable sources.
Here are my experiences with some of my portable options:
I start with the included USB dongle, DT01 Pro. It does a remarkably good job. Kiwi Ears’ Allegro Pro, is similar but a bit warmer sounding. The Letshuoer DT03 also performs well, but not really better than the DT01 Pro. The Alpha XI1 ONIX is good, adding a warmer touch.
The xDuoo Link2 Bal2 is a tad more refined than the previous options, the Dragonfly Cobalt is also a step up, with more authority and detail. The Cobalt and the xDuuo are very similar and my favourites so far.
Finally, the Chord Mojo is yet another step up, with better resolution and generally excellent delivery.
In conclusion I was very surprised to experience that the S12 Ultra performs so well with all of the USB DAC/Amps, even though it scales with better gear.
CONCLUSION
The Letshuoer S12 Ultra is an excellent single-driver planar magnetic IEM with impressive all-around performance. Its tuning is well balanced, featuring powerful yet controlled bass, slightly dark mids, and clear, somewhat crisp highs. While it performs excellent across the board, the true standout is the bass, which is simply exquisite.
Although the older S12 Pro still has its strengths, I prefer the new tuning and consider the S12 Ultra the best S12 iteration so far. The S12 Ultra is also noticeably easier to drive than the S12 Pro, and the included DT01 USB dongle does a great job.
In conclusion, I can wholeheartedly recommend the Letshuoer S12 Ultra.
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