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Review - Letshuoer S12

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Also available on YouTube in Spanish: Acho Reviews YouTube 

These IEMs are a set that I was very interested in trying out and while I was in Miami, Antdroid very kindly loaned them to me. I got to spend a day or so with them, with a very positive first impression, and was about to create a mini review for them when Letshuoer reached out to me, offering to send them to me for review. I was obviously very happy to do a full review of them and a few weeks later, here we are.

Therefore, these IEMs have been sent to me by Letshuoer in order to review them and give my detailed impressions on them. They have not made any specific requests (although I will share the link to them below) and my review will aim to be, as always, as honest and unbiased as possible, although you should always consider the fact that these IEMs did not cost me anything.

You can find the S12 direct from Letshuoer here:

You can also find them on Amazon UK here: 

(non-affiliate links)


There has been quite a surge of planar magnetic IEMs lately, gaining quite a lot of popularity due to them having improved a lot since previous releases. Two of the most popular have proven to be the Timeless and the S12, the set I have here today.

I did get to try out the Timeless while away and published a mini review of them that you can find here. In that mini review, I compared them quite a bit to the S12, as I had tried them side by side for a day or two, and I mentioned that the comparison probably didn’t make much sense due to the fact that I didn’t actually publish the mini review of the S12. I just mentioned above the reason for not publishing the mini review and I am very happy I have got the chance to test these IEMs over a longer period so that I can share more detailed impressions.

I also mentioned in all of the mini reviews (unless I forgot to mention it in any of them) that when I spend a more extended time with a set of IEMs (or headphones), my opinions may change over that period. I may grow used to some of the things I find strange at first and learn to like them more than I do over a short period, but it can also go the other way, I may start noticing things that I didn’t at first and which make the IEMs not as pleasant for me.

In this case, my impressions from the short period I spent with them have not changed much, if anything, I like them even more than I did over the short period I spent with them. I said in the 7Hz Timeless mini review that personally I preferred the S12 (although both are great sets of IEMs) and although I haven’t had a chance to spend a longer period with the Timeless, I still maintain my decision.

Anyway, enough chit chat and let's get on with the important stuff.


The packaging of the S12 is simple, with a basic white box and an image of the product on the cover. Inside there is nothing out of the ordinary either, but that doesn’t mean that it doesn’t come with everything that a set of IEMs should.

Inside the box we get the IEMs, multiple sets of tips (3x sets of foam in their own hard case and two types of silicone, 3 sets of each type), a nice compact carrying case that is smaller that what is usually included but is still big enough for the S12 to fit without issues, and a cable.

You can choose which cable you would like including when placing an order for the S12 (via the official page), choosing between 3.5mm and 4.4mm terminations, with an option of silver or nebula grey for the IEMs also. In my case, I went for the 4.4mm cable and the cable is of very good quality, although it is a little thick for my personal tastes. While it is not what I would pick personally, the cable has actually grown on me a lot over the past week as far as comfort, and there is no denying it is a great looking cable.

So, everything you need is included in the package, I cannot complain at all in this sense.

Build and aesthetics…

The build quality is good, there are no apparent issues that I can spot, and everything in the package seems well manufactured, including cable, IEMs and tips.

As far as aesthetics, these are quite simple. The shells are fully metal and are finished in a simple, no frills, silver colour (in my case). Obviously aesthetics are just as personal as comfort but they don’t strike me as anything that should offend the vast majority of people.

I just mentioned above that the cable is a great looking cable, so again, I have no complaints.

As far as comfort, I find them very comfortable, fitting my ears perfectly and although I would prefer a slightly lighter weight cable, it has also grown on me (possibly aesthetics taking a part in this). For tips, I had been using Xelastec tips for a lot of my listening time but I decided to try out the spring tips that are included with the Moondrop Chu (review of the Chu coming soon) and I have found that I not only find them to have great sound but to also be extremely comfortable without the hassle of the Xelastecs.

As I just said, comfort is as personal as aesthetics (or even more so), so everyone is going to be different, but I find these more comfortable than the Timeless and also less “attention seeking” with regards to aesthetics.


Just a reminder that all tracks mentioned in this section are clickable links that will allow you to open the song in the streaming service of your choice, allowing a direct reference of the song I am talking about.

Here is where I fell in love with the S12. Anyone who has followed my headphone reviews will probably already know that I am a planar magnetic lover, and in the case of IEMs, it seems to be that I am of a similar fashion. I have had the Audeze iSine for quite some time now and I like them, except for the fact that they need a ton of equalisation in order for them to have a decent tuning. The S12 does not have that issue. The tuning out of the box is great, in my opinion of course, and I have found that they are probably the most pleasurable set of IEMs for long listening sessions that I have spent time with so far.

Moving through the usual sound categories, starting with subbass as always, there is no roll off here, at least not that I can hear. Putting the S12 through my usual subbass workout which is “Chameleon”, there is plenty of presence to give me the sub rumble that this track presents, without them seeming to lose control at any point. There are many sets of IEMs that can get that low end rumble with this track but once the subbass starts to mix with the midbass, things can get a little hazy. That is not the case with the S12, they keep things nice and collected, offering a great presentation of this track which is better than the vast majority (almost all, especially at this price) of IEMs that I have tried.

Moving into the midbass, if we look at the graph of the S12 vs my target preference, there is a little more than I request.

(all my IEM measurements can be found and compared on

However, targets are just a rough guidance and we shouldn’t get fixated on things adhering to targets too much, as sometimes a deviation can actually sound better, depending on how that is presented and controlled by the IEMs in question.

In the case of the S12, the midbass is extremely well controlled, making things sound precise and clear, even when a track is busy in these areas. Even activating the XBass boost on the Gryphon, where bass becomes overpowering for me personally (depending on the track of course), they still keep control and definition of the notes.

Tracks like “No Sanctuary Here”, which have a strong bass presence but need cleanliness to sound their best, sound clear and, well, great on the S12. More “old school” songs, such as things like “Whole Lotta Love”, benefit quite a bit from the additional presence of the midbass, making the bass guitar of John Paul Jones become a little more present but without it sounding out of balance with the rest. The live performances by Clarke, Miller and Wooten (which is unfortunately not available on streaming services, at least as far as I know) are nicely presented with the separation of the 3 bass guitars being quite easy.

Moving into the mids, there is no bleed, no muddyness, just a nice clean transition. There is also no recess in the mids, keeping them from losing space to the midabass. The slap/pluck of “Elephants on Ice Skates” comes across as well balanced, without it being overpowering in the lower notes and without it losing in the mids to the brass section.

Listening to some of my favourite styles of music, such as acoustic and simple vocal/instrumental tracks, the mids are smooth, without anything sounding harsh or out of place. There is the usual hint of “coldness” that this kind of music can portray on planar magnetic drivers, which may sound a little different if you are used to dynamics but it is something that I have grown to enjoy from infinite hours spent with planar headphones. 

A listen to “Diamonds on the Souls of Her Shoes”, which can be a little harsh on the higher mids and lower treble on many sets, still presents a little harshness to Paul Simon's voice if volume is pushed but in general it is again well balanced and is not painful (unless pushed way above my usual listening levels). “Don’t You Worry Child”, another track that can easily become harsh to my ears, is much better than I expected and is quite listenable. 

Hip hop, which is something that can suffer quite a bit in regards to vocals when the midbass is boosted and the higher mids are not overly present to compensate, actually sounds as it should. Or at least it sounds like I expect it to sound after many decades of listening on many speaker set ups and other headphones. As an example, “Make Noise” by Busta Rhymes and Lenny Kravitz, has the vocals quite recessed in the mix, which can either totally disappear or become boosted, depending on the system, seem to have the same presence as I have heard on many monitor and live set ups.

Moving into the treble, there is a nice extension and plenty of “air” to make it thoroughly enjoyable for me. As a sibilance test, using “Code Cool” as usual, there is a slight hint of sibilance on a few of the “S” by Patricia Barber, but certainly not enough to make the track painful or difficult to listen to. This is something that can be the case on many sets of IEMs and headphones, with her voice either being harsh and sibilant, or subdued and pushed back. Again, I would say that the S12 do a great job of keeping it where it should be.

While the detail of these IEMs is very good, I do feel that detrail retrieval may not be the strongest point of the S12. I only listened to the Timeless for a day or so, although I got the possibility to test them side by side with the S12, but I got the feeling that as far as detail retrieval, the Timeless did have the slight edge here. Neither sets are going to compete with something like the Helios (a set of IEMs that is 5 times the price) but both are very good, not just for this price bracket. 

At no point do I get the sensation that details are missing, they are all there, just maybe not as apparent as they are on some other sets. Listening to the intro of “All Your Love Turned to Passion”, there are some details in the left channel from the acoustic guitar that can be extremely impressive when a set of headphones presents them well. In the case of the S12, the details are there but they are not something that stand out and make you say “wow”, something that does happen on certain planar magnetic headphones like the higher end Hifimans, but this is obviously not even a comparison that can (or should) be made.

Soundstage is also good for a set of IEMs but without being outstanding. I really don’t find many IEMs to have a large sensation of space in this regard and the S12 are no exception. I would say they are on the higher side of average but not something that give the impression of having a huge amount of space for images to spread out. For example, “La Luna”, which is a binaural recording, does give a nice surrounding sensation but it is slightly closer than on open back headphones (which is again, not a very fair comparison).

The placement of images is very good however, with pretty good precision inside the soundstage that the S12 do have to work with. As I just mentioned, “La Luna” is easily placed around you, and also things like “Strange Fruit” show nice placement of the different layers of vocals.


Well, I guess I have made it pretty clear that I like the S12, I don’t think there is any doubt about that. When I made the series of mini reviews, I got to spend some time comparing the Timeless and the S12 (I mentioned the comparison quite a bit in the TImeless mini review here), two sets that compete pretty closely with one and another, and I mentioned that I personally preferred the S12, at least after a day or two of use. I also mentioned that more time with a set sometimes makes me like (or dislike) something more and with the S12, I have grown to like it even more, making me very happy to use it as my daily IEM. I obviously haven’t had more time with the Timeless since then, but if I had picked the S12 out of the two based on the time I spent with them both, then I would have absolutely no regrets.

I read Antdroids review of the S12 and he said something that completely clicked with me and that I agree with 100%. I am paraphrasing from memory here but he said something along the lines of “The S12 are like the Hifiman HE400se, they are maybe not the most detailed option and don’t have the fastest of planar speeds, but there is a decent amount for the price and the tonality makes up for it” (or something along those lines 😉 ). I couldn’t agree more. The HE400se are a set of headphones that I just like, they are by no means the best performing headphones that I have but the overall sound is just pleasurable and is something that I can enjoy for hours of simple music listening. I feel the S12 are the same, I have come to not expect them to surprise me with things I didn’t know existed, but I have no doubt that they always perform well, no matter the track, and are a pleasure to listen to.

I was also surprised to find that they work really well with the iFi Go Blu. Due to expectations, I thought that the Go Blu would not be able to drive these IEMs well, but I was mistaken. Using the balanced output, it performs very well and has become a very portable set up that I am more than happy to use all day while away from my usual set ups, meaning I don’t need to rely on the Gryphon for portable power with these IEMs. I think this is probably more of a praise towards the Go Blu than the S12, however, it is something that has made me very happy.

If I needed to resume this (very long) review into a TLDR, it would be “A set of IEMs that I enjoy immensely and while not the highest performers out there, a perfect solution for my EDC”.

All FR measurements of IEMs can be viewed and compared on
All isolation measurements of IEMs can be found on

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