ThieAudio Legacy 4 IEM Review

A truly great pair of IEMs is often harder to come by if you don’t want to break the bank. However, brands like Kinera, Queen of Audio, and IBasso, have challenged this notion, offering quality builds and sound resolution for an affordable price. ThieAudio looks to continue that practice with the Legacy 4, an earphone that’ll cost you $195. If you upgrade to their 2.5mm balanced cable, it’s around the same price as the Kinera Freya, an IEM I found to be exceptional with its beautiful design and balanced sound signature. Let’s see how the Legacy 4 stacks up.


What You Get

When you see the packaging of the Legacy 4, you can tell you’re in for a treat. Removing the lid revealed a large carrying case, which contains all the supplies you’ll need for these earphones. The earpieces themselves are stored in foam inserts, keeping the delicate housing safe. Underneath them is a selection of 6 ear tips in a variety of sizes. Lastly, there’s a smaller, more portable case within the larger case containing the Legacy 4’s OOC 4-core custom 2-pin cable. ThieAudio gives you everything you need with a neat and organized presentation, however, there’s one item I would have liked to see included, and that’s a small tool for the two switch tuning system. 

In hand

Look and Feel

What I really like about the initial appearance is the size of the housing. Sometimes IEMs like this will have a beautiful design, but the shell makes the feel of them a bit awkward. The Legacy 4 goes for more compact size and a body shape that should universally fit most ears. The faceplate design is this glittery swirl that is individually crafted for a unique pattern on each piece. The Legacy 4 is made from a medical-grade German resin to accomplish this architecture with elegance. The rest of the shell sports a semi-translucent grey coloration that gives you a slight peek under the hood. The fit is very seamless and has a nice level of comfort. Throughout my hours of listening to Legacy 4, I never felt any pressure or fatigue. They might not have your preferred level of isolation, but I felt that everything about this fit was natural and well built. 

nozzle and housing


Inside the housing, the Legacy 4 supports an 8mm poly-membrane Knowles dynamic driver with three balanced armatures. This hybrid system contains a 3-way crossover network and a 2 switch tuning system that will give a slight boost to the bass or the mids. I previously mentioned that I would have liked to see the Legacy 4 come with a small tool since the switches are very tiny and you may not have any implement around that can operate them properly. The single dynamic driver relegates the low end, while the other three armatures contain low-mids, mids, and highs. The aim of this design is to convey a natural timbre with a more impactful response. 

IEM wrapped


ThieAudio wants you to be able to use their IEMs with any 3.5mm connector. You can also upgrade to get an additional EST 2.5mm balanced cable with 3.5mm and 4.4mm adapter. They’ve given the Legacy 4 a very low impedance of 9.4 Ohms. I started listening with my normal PC headphone connector, and I immediately found a comfortable level of gain with plenty of room for a boost. Smartphones will also have this benefit, as long as you have the right adapters or jacks. Even with the low resistance, I don’t believe the Legacy 4 will ever blast your ear off, but you should still be careful where your input gain is set. 


Space here is impressively wide with some great separation, making the image very defined. It sticks to a mostly linear response but there is some solid layering at play, especially with forward-facing vocals with music beds articulating well underneath. With Legacy 4, you can expect a clear resolution, as well as an accurate representation of pan movements and stereo imaging. I would have liked to hear some more depth out of these earphones, as I felt like the image offered enough headroom to really delve deep into a more immersive sound field, but unfortunately, the Legacy 4 never goes there. However, if you’re looking for a stage with precise accuracy and stability, then this will definitely satisfy you.

Low End

This is a bass that is all about feel. The sub-bass has a nice deep resonance that emanates from your chest with great impact and a satisfying smoothness. This makes for a crisp textural quality that will make any listener happy. I loved listening to the deep grooves of a Thundercat track with the Legacy 4, especially the track “Dragonball Durag” where the main kick drum pulsates through the mix without bleeding into the other sections. 


Slightly thin, but exceptionally clean for the most part. Acoustical instruments almost have a crisp texture, but the real standout here is their spatiality. Instrumentations offer these detailed presentations that come across as super clean and articulate. Vocals especially have this forward presence that makes a passionate performance really pop on the Legacy 4.


There are some really great details here, but most of the thinness of the Legacy 4 starts to show itself here. While percussion elements offer some nice sparkle and clarity, some listeners might not be a fan of the sharpness that happens sometimes in the upper treble. 


For $195 to $249, the Legacy 4 brings a lot of intricacies to its sound signature while offering a pretty design. It has the perfect comfort level for an IEM and the overall aesthetic will have anyone interested in their sound. Overall I feel really good about this sound, and I think ThieAudio is able to join this exclusive club of top-quality IEMs for less than five hundred bucks.

Pros and Cons

Pros: Wide stage, great fit, design, price

Cons: Some sharp highs

ThieAudio Legacy 4 is available from Linsoul.

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Alex S. is a sound designer and voice-over artist who has worked in film, commercials, and podcasts. He loves horror movies and emo music.