Thieaudio Legacy 3 Custom CIEM Review

I was pretty happy with the universal version of theThieaudio Legacy 3 three-driver hybrid IEM, but given that the cost of getting the Legacy 3 in a Custom IEM form-factor was incredibly inexpensive, at just $179 starting up to $219 depending on design choices, I had to give it a shot. I have owned 2 other custom in-ear monitors before, as well as have had custom ear tips made for the Campfire Solaris, and so I knew what I was getting into for the most part.

I reviewed the Universal Legacy 3 a few weeks back and that can be found here:

While I do review products sold and sent by Linsoul from time to time, both universal and custom versions of the Legacy 3 were purchased out of my own pocket at regular price. I ordered these just like any normal person would, so my process of going buying these may be useful.

The Process

Normally to get a CIEM, you start with getting ear impressions made typically by an audiologist, or someone who knows what they’re doing. They will take a 2-part mixture of special ear impression silicone material and mix it around and put it into a syringe and inject the material into your ear cavity and create a nice clean mold of your ear. This can then be sent off to the manufacturer to use as a mold to cast the CIEM shell from. In my case, I’ve actually learned how to do the impressions on my own, but I highly recommend getting it done by an audiologist.

In the case of the Legacy 3, Thieaudio has an option to just send a 3D file of your ear impressions if you have that available. Luckily, I actually had a 3D scanned file (STL format) of a previous ear impression I made last year available, and so I sent that off to Thieaudio for creating my IEM. This is possible because the Legacy 3 and the Voyager 3 are 3D printed designs, so having a compatible 3D printing file will expedite this process significantly, especially during our COVID-19 lockdown times.

The actual fabrication process took about 2 weeks and I was received the CIEM within 3 weeks of my order placement, which was pretty fast turnaround for a CIEM. Some can take 3-4 weeks to make before shipment, and some can take several months. When they arrived, they looked quite nice and finished well. The packaging was different than the universal sets I received as well. It does seem like Linsoul and Thieaudio changed the package presentation on the newest sets of both universal and custom Legacy 3s.


The box design was different with a more luxurious, green, look to it. Inside was an even larger, but more nicely put together fake-leather carrying case with the IEM, cable, metal tip for changing switches, and ironically, a set of tips. Tips for a CIEM? This must be an oversight or a pre-packaged set.

The cable is the same cable that is found on all Legacy 3 units, however it seems that if you go with a custom version, no matter if its customized design universal or an actual custom CIEM, the connector type is different. On the standard models, c-pin connectors, also known as qdc-style, are used, which are raised from the shell, and the cable actually fits around it with 2-pins inserting into this raised part. Once attached, the connect covers up the raised portion and becomes very clean fitting.

The custom versions, however, use a more traditional 2-pin connector, which is flush with the shell and the normal 2-pin cables will sit above the shell, with the connectors slotting in below the shell surface. Either way is fine for me, but just keep that in mind if you are planning on getting a new cable to go with it. The universal style c-pin will work with any 2-pin cable-type, however the recessed/flush 2-pin will not work with c-pin cables.

This cable has a nice appearance to it and I like its lightweight and easy to move does not tangle much. It also has some shiny connectors and splitter, which are stylish and attractive. It doesn’t feel quite as nice as it looks, but keeping the weight down is more important to me than looks in the long run.

As a quick recap, the Legacy 3 is a hybrid IEM with a single dynamic driver and 2 balance armatures. The CIEM has a single vent near the connectors on the shell, and does not have one near the nozzle. The CIEM is very lightweight and looks fabulous. I picked the AW11 blue sparkle-flakes look with a dark royal blue translucent shell color.

The CIEM is not quite as tight-fitting as some other ones I’ve seen as well as my Hidition Viento CIEM. The Viento is very tight around the ear as it fills up the entire cavity and extends further into the ear canal than the Legacy 3 does. Instead, the Legacy 3 is smaller and fits extremely comfortably, without any adjustment time for me. It’s slightly larger than the universal, but not nearly as drastic of a change as it was for the Viento to the custom Viento, which was over double the size.

When I first got the Legacy 3 CIEM, I was actually unsure about it, since it fit so comfortable and was a little shallow and didn’t feel like it sealed very well. I actually resorted to trying to apply more material to the canal by using nail polish which didn’t work well for this case, and then using medical tape, which did. But it wasn’t super comfortable. I was thinking of ordering comply wrap, but I decided to just try it bare again, but this time with some Oto-Ease ear lubricant.

Oto-Ease is a lubricant that is used for hearing aids and CIEMs and recommended for use when you are first getting new CIEMs or hearing aids. It helps slip them in easier, and also can help couple the shell to your ear. In my case, the CIEM was small, so putting them on was a breeze without the gel, but adding it as a coupling agent to my ear made a world of difference. Seal was tight and the bass response was shaking.

I had actually read on a site that over a few days of using the lubricant and with your natural wax build-up, the shell can start to seal better. There is some truth to this because over a few days, I actually didn’t even need to use the lubricant to obtain a nice seal and get the bass impact I was lacking when I first received the CIEM. This may go away if I wipe the residuals from the CIEM and I’ll have to couple it again with lubricant of course, but it does beat using medical tape or perhaps resorting to using Comply’s Soft Wrap foam material specifically made for improving leaks in CIEMs and Hearing Aids.

I was also still able to get it refitted and reworked from Linsoul and I have been in contact with them about it, however I am currently thinking this shouldn’t be a problem moving forward. I do think that a slightly deeper nozzle length would provide better seal in general though.


I don’t want to completely go over the sound profile of the Legacy 3 again, as I covered some of it in my previous review, however there are some significant changes with the CIEM. The first thing I noticed was two-fold, both relating to treble response.

On these measurements shown for the CIEM version, I did my best to position it and get it to be as close as I could given the challenges of measuring a custom IEM shape on the IEC711 coupler. This required the use of a bored out foam tip, silicone putty, and minimal manual finger force applied to the top of the CIEM to keep it in place and to minimize bass leakage. This is why there are some jittery bass response in these graphs. The graphs have also been smoothed out a little more than normal, however this mostly cleaned up the bass response, and didn't really alter the rest of the frequency spectrum.

With the universal set, I felt the upper treble was lacking. In some of my test tracks, like “Dreams” by Fleetwood Mac or “Restless” by Alison Krauss, there’s quite a bit of cymbal splashes and stringed instruments in these songs. I always felt there was just a little bit of resonance missing, and some of the instruments sounded dull and lacking life with the Legacy 3 universal. This isn’t totally surprising given its measurements, and comparing it to its competitors in this price range. The Moondrop Kanas Pro and KXXS, for example, also have a laid-back treble region and a muted upper treble. I had corrected this by adding 3dB at 12KHz in PEQ or adding 5dB at 16KHz on a 10-band EQ.

The CIEM version, with its deeper fit, brings clarity and shimmering treble back. The same complaints I had on my acoustic tracks, including jazz, orchestral, and bluegrass music, are no longer complaints. The music sounds full and alive again, and without EQ usage. This made me smile a bit.

On the same song, “Dreams”, I also found that the lower treble sounded much smoother and clean. My first song I use when I test new gear is typically this track, as there’s a variety of different instruments at once, and I just love Stevie Nick’s voice and lyrics in this song. The album in general is well recorded, mastered, and features a variety of singers with different styles and the album spans a wide range of sound. Anyway, the smoother and cleaner sound seemed to show up in my measurements as well, as the range lacks any significant dips and peaks, although slightly more recessed, and smooth.

I also found the CIEM is less shouty. There’s not as large of a pinna gain in this version, which in some cases may make some vocals not quite as exciting and forward, but it does make this IEM very fatigue-free. Again, the key word here is smooth. That’s not to say it’s not a little shouty, but I don’t find it bothersome personally.

The mid-range is very balanced and warm. I also think that this version sounds a little more refined here, and while it still lacks superior resolution and depth and imaging chops, it is improved a bit over it universal, but not competing against my Viento CIEM or other top tier IEMs. It still performs well for its price, even with the additional cost of getting the custom model.

Bass has similar quantity and quality. There’s a great deal of slam and punch when you get a good seal, just like I felt with the universal and finding the right tip to prevent any leakage. In Daft Punk’s “Doing It Right”, the bass absolutely hits hard with punch, a nice decay and has plenty of body and rumble with minimal bleed. Some may complain it hits a little fast, but I find it a nice balance. Again, I feel like it does the job well, but does lack a little bit of resolution and some needed texturing in some songs, but I am not asking for the world at this price range. I think it outdoes a lot of stuff here but there are times where I find the bass a little smeared.


I didn't discuss much about the switches, because I feel like they are unnecessary on this IEM. The changes are very subtle. They change about 1 decibel across the bass and lower mid-range and 1 decibel across the treble range depending on which switch you use. This is almost inaudible to an extent, with the "biggest" change being all on or all off. Even then, it's rather hard to distinguish the differences. For reference sake, here's my best attempt at measuring the switch changes:

Final Remarks

In general, I think the CIEM is a great deal for under $200. I can’t think of many CIEMs that are priced this low, with quick turnaround to boot. I think the CIEM fit makes this tonality better, and the technical performance improved over the universal. My biggest gripe with the universal, treble extension, was resolved with this version, and on top of that, I find the overall treble and pinna compensation region to be smoother and more refined.

Overall, I think this CIEM is a good recommendation for anyone who wants to give CIEMs a shot but do not want to spend a lot of money like most CIEMs cost. It’s a budget way to give customs a try and see if you can live a world without tips. I highly recommend CIEMs myself, but it isn’t for everyone and re-sale value takes a big hit if you do change your mind later. But that said, the Legacy 3 CIEM is a very welcome addition to the market and I am looking forward to more products like this.

Video Review


  1. i just received my pair of customs today. i do agree with you about the fit. mine felt a little shallow and just the tiniest bit loose at the tips. i am going to try the oto ease to see if i can get that tiny bit of seal. the bass does sound good but especially in my left ear the seal isnt 100%. Even with this issue, i am impressed for what you are getting for the price. this is a great experience into the world of ciems. I listened to primarily metal today and found them to be very solid. thee are all first impressions so time will tell how stack up. One thing of note, i ordered the oriental white with blue flowers and the iem is really pretty.

  2. For anyone looking at this review in 2022 or later.
    I contacted Linsoul regarding getting a custom set of these made.
    They asked me to get impressions made and send them photos for confirmation.
    Once I had impressions made and sent to them, they 'then' informed me that they will no longer customize this model.
    They did however 'kindly' offer me a list of $1k+ models to choose from.

    Just a word of warning to anyone looking to get these from Linsoul, they no longer will customize them and, as of Sep 2022, they no longer offer a budget friendly custom IEM.


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