Thieaudio Legacy 4 Review

I thought Thieaudio was going to slow down on the releases of their in-ear monitors but then they come out with the Legacy 4. This four-driver IEM comes packed with a single dynamic driver and 3 balanced armature drivers and retails at $195, placing it in-between the Legacy 3 and Legacy 5, both of which I've reviewed this year. 

The product was sent to me by Linsoul, who are the makes of the Thieaudio brand and are found at


The Legacy 4 comes with a new dynamic driver that has not been used on previous Legacy series IEMs. This new DD is perhaps a welcome change as one of my biggest negatives with the previous Legacy 3, Legacy 5, and Monarch/Clairvoyance, were mainly triggered by the lack of resolution and softness of the bass range.

In addition to this change, the packaging is all-new, again! It seems like every unit I've gotten has come with a new unboxing experience and this one has been my favorite yet. The L4 ships in a large nylon zipper case, which when opened, houses the IEMs, matching smaller case, and tips in their own small compartments within the larger case. 

The cable included is also my favorite of the ones Thieaudio has included in any of their sets to date. This one is white colored, and is braided with a soft sheathing material that has a lightweight, but durable feel to it. It's extremely easy to wind and unwind without tangling, and is very maneuverable. I also just like the overall simple modern look of it.

The shell design is small and petite, much like the Legacy 3 in size and shape. The faceplate art is available in only one swirl pattern that features a mix of blues, yellows, and orange within in a semi-translucent black shell. There's a single vent on the shell, and it also features a pair of tuning switches which add or subtract mid-range to the IEM in what seems like just 2 configurations total in my measurements.

Sound Impressions

The Legacy 4 has a well-balanced signature that does stray a tad bright in the lower treble regions that I think some may find fatiguing over time, but this also provides a clean clarity to the overall sound. It surprisingly has good extension for this price class and I find it sounds like a better tuned and more technical Moondrop Kanas Pro or KXXS, and is priced just a few dollars more than those well-received IEMs.

The new dynamic driver which handles the low end seems like a large improvement over the previous dynamic driver found on all the previous Thieaudio IEMs. This new one has better microdynamics allowing for better punch and resolution, and does not fall behind the quality of the BA drivers as much in that department. It still isn't the best dynamic driver I've heard in an hybrid IEM (MEST!) but its quite enjoyable for this under $200 price point.

It's no longer blunted and smoothed out, and  I don't jokingly call it the Blon DD anymore. It's also a marked improvement over the Moondrop KXXS and Kanas Pro low end sound. Those two are a single DD which handles the entire frequency response.

The mid-range of the Legacy 4 can be altered depending on the dip switch choice. While there are technically four different combinations of switches, in my testing and measurements, only two configurations make a difference. If you leave the RIGHT side on or off -- in other words, OFF-OFF and ON-OFF are the same, and ON-ON and OFF-ON are the same. This is similar to the Legacy 3, where they could have just kept one switch and saved time and effort.

The midrange does change from a flatter and thicker sound to a more recessed sound that changes the overall sound from a mild U-shape to a mild V-shape signature overall. I found that I enjoyed the Right ON (flatter mid-range) more for most things, though with rock music and some more pop genres, the RIGHT OFF signature worked well as well. I would also prefer this for movie watching.

The treble range on this unit can get a little hot. It is just a tad brighter than my preferred sound signature, but only slightly. For those who are familiar with the Moondrop Blessing 2, it is pretty similar in that type of level of treble. That said, I do find this one behaves a little more so, by being more treble tame, than the Blessing 2 in terms of overall brightness, and it does not sound quite as lean, mostly due to the fact that it has a bigger bass shelf.

That said, when I listen to music with a lot of stringed twangs, those instruments (primarily guitars) can come across quite forward and tizzying (is that a word?). Some piano notes came across this way as well, with strikes coming in a tad sharp at times. I wouldn't say I found these fatiguing, but I am one is quite accustomed to listening to slightly brighter than neutral gear, and the peaks in the 5KHz region is common amongst some of the gear I own and listen to regularly. For those who are sensitive to this area, it may be something to be wary about.

Treble extension is quite decent for this price range, and specifically I am going back to talking about its contemporaries here -- the Moondrop dual, and even the Etymotic series, which are similar in tuning and capability. Both the Moondrop and Etymotic series sound just a bit flat and missing full treble extension. The Moondrop twins are more guilty of this however. With the Legacy 4, it does extend treble, but maybe not with the same amount of air and shimmer as some other gear I've heard at higher price points. That said, I am perfectly pleased with this amount for price range and I am  quite content with the overall sound in general.

I've spent some time talking about it with regards to its competition, but how does it stack up within its own family? 

I gave the Legacy 3 a mostly supportive and recommendation earlier this year and even bought the universal and custom versions. It's a great deal for the price, however my biggest complaints with it were its lack of technical capabilities. This had a lot to do with dynamic driver sounding very mushy, but it also had a very forward and 2D sound to it. This means, I never really felt the depth was there, and it lacked good imaging and instrument separation. 

The Legacy 4's improved driver configuration seems to help out a lot here. While the sound signature is similar, the L4 does not have as much issues with mushy bass resolution, and it has a major upgrade to the soundstage and imaging. The resolution is overall much improved on this set and I would highly recommend someone who is thinking what to get between the two, that its well worth the extra $70 to upgrade to the Legacy 4. The L3 is a little more laid-back and pleasant sounding though, and should be less fatiguing due to its tamer treble response and it does not have that sharper 5KHz sound to it, but it does lack a little bit of the airy treble that I like about the L4.

When we talk about the next one up the price list, it gets a little more interesting. The Legacy 5 is priced at $50 more than the Legacy 4 and adds an extra BA driver to the count. It still uses the older DD though and that is obvious as my major complaint with the Legacy 5 was, again, the mushy, blunted and lower quality bass region. The L5 is also a more warm and lush sounding IEM, with a significantly tamer and thicker sounding mid-range and treble. It's full-bodied in everyway, while the Legacy 4 sounds quite lean compared to it, and has an airier overall sound.

The L5 isn't as bad in the major technical departements as the L3, but I'd say the L4 is on-par and if not surpasses the L5 in every category -- soundstage, imaging, resolution, texturing and layering. I may give the L5 a nod for coherency, because I do feel the sharper BA sound in the L4 makes it sound a little disjointed from the low end DD.

Finally, many have asked how this stacks up to the Monarch and Clairvoyance -- the twins that I believe define the capabilities of Thieaudio. Both of these have well-thought-out tuning and have solid technical capabilities. I think these two still stand top of the Thieaudio brand that I have tried. I have not tried the Voyager 14 and Legacy 9 yet, so keep that in mind. 

While the Monarch and Clairvoyance use that old dynamic driver that I did not like, there are a set of BA drivers that are also used down-low to help keep resolution at a good level on these two. Both the Monarch and Clairvoyance have improved resolution and don't have as a fatiguing sound, though the Monarch is a bit shouty in the 1K range, which may affect some.

The Legacy 4 has just a slightly fuller sound in the low-end, but it does have a brighter treble region, and some may not like that. Again, there's an emphasis in 5KHz range, so it'll provide a lot of presence to guitars and strings for the music I listen to.


The Legacy 4 is yet another solid addition to the Thieaudio lineup that is continuing to grow and most of the ones I've tried are well-tuned and fit solidly within their price points, except perhaps the Voyager 3. I have got to say that I am impressed with this whole thing, and they continue to up their game in both sound capability, and also the entire package, which is full of accessories and a unique and meaningful unboxing and package of tools to use.

This one definitely competes in its price point and will get a recommendation from me. It's enjoyable all-around, but it does have a little brighter than neutral treble, so just be mindful of that when considering products with it.