ThieAudio Legacy 9

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Pros: massive globs of bass
- sparkly, splashy treble
- solid upgrade over Legacy 3
Cons: lacks resolution
- plethora minor issues with tuning
- not for bassheads


Thieaudio is a sub-brand of Linsoul, and they have two lineups: Their all-BA Voyager lineup and their Legacy, hybrid lineup. To this effect, the Legacy 9 (L9) is using 1DD+8BA and retails for $549. After my previous experiences with their Voyager 14 and Legacy 3 IEMs, let's just say my expectations going into listening the L9 were...not very high. Both of those other IEMs have what I can only describe as "cucked" midranges. But despite the low bar set by its predecessors, I do think that the L9 is at least a solid IEM that is perhaps not quite conducive to its asking price.




The Tangibles

I’m not going to allocate too much time here just because this is a loaned unit, and I didn’t receive any packaging by my own request. Build quality seems good to me. The L9 is of average size for an IEM (think original Moondrop Blessing size), and it weighs very little. Personally, I had no issues with the fit but that's 100% subject to one's own, unique ear canals.

Sound Analysis

Disclaimer: This unit was kindly lended to me by a member of the audio community. At the end of the demo period, it will be returned to him. I have no other conflict of interest, and as usual what follows are my honest thoughts.

Testing Methodology:
  • Tripowin C8 cable and silicon tips. I’m sure one could tip-roll to adjust the sound signature to somewhat better align with their preferences.
  • FLAC files off of a Shanling M0.
  • Burn-in – I don’t really believe in it unless we’re talking about your brain and ears getting used to the sound. For what its worth, I rarely hear differences after the fact, and this was a loaner anyways.
  • The L9 takes very little power to drive, and I had no issues driving it off of any of my sources.
Bass: The L9 has a strong bass emphasis, probably bordering on bass-head levels. Admittedly, I am a bit of a bass-head, so I very much enjoy this. That being said, the bass is not the cleanest. Having recently listened to the Sony IER-Z1R, which is basically the bass-head IEM endgame, it's clear to me that the L9 lacks a lot of control in the lower frequencies. I hear good texture, rumble, and extension, but the attack transients just aren't as pronounced as they should be. Furthermore, if you're not a bass-head, it could definitely come across as bloated or as having too much quantity.

Midrange: There's not much to talk about here, and coming from the Legacy 3's midrange - which I couldn't stand - that's definitely a good thing. Vocals come across as thick and smooth on the L9. Nothing outright wrong and nothing particularly noteworthy.

Highs: Damn, I love the L9's treble. I've sometimes heard of treble being described as "sparkly" and I never really understood that sentiment, perhaps because of my limited experience with IEMs. Well, now I do. The L9's treble zings, sparkles, and splashes with good extension. It's most definitely present, and I love the detail and air it adds. That being said, I acknowledge that it might offend some who prefer a more muted treble response.

Overall, the L9 has a warm, dark tonality. There's a little bit of BA timbre but nothing too egregious. I think you'll notice that I'm a bit split on the L9's frequency response. I've pointed out more than a couple deficiencies with it, and yet it aligns really well with some qualities I desire. But as much as I (subjectively) like the L9's tonality, its technicalities do leave something to be desired. Imaging and soundstage are decidedly average, and in general, resolution is only decent. It's also not the fastest IEM, particularly in the bass response which can slightly lag behind the midrange. It doesn't do anything blatantly wrong here...and yet, I can't help but feel that it's lacking something especially at its price point.

Select Comparisons

Versus the L3 ($119), the L9 has a more powerful bass boost that is slightly less controlled, a thicker midrange, and much more sparkle in the treble. Both are warmer, darker listens and the L9 suffers less from timbre coloration. In terms of technicalities, the L9 also handily edges out the L3. It's a clear upgrade minus being several times the L3's price.

Versus the Fearless Audio S8 Pro ($489), from memory the S8 is more in-your-face. While the L9 has more quantity to the bass, the S8 Pro's treble is more pronounced and verges on aggressive at times. Mids on the L9 are thicker and less textured. Both suffer from BA timbre to a certain extent. While I prefer the tone of the L9, the S8 Pro has a clear advantage in terms of technical performance and is a good deal faster. The S8 Pro is the better value, but some may find it too aggressive.

Versus the Moondrop Blessing 2 ($320), once again the L9 has more bass quantity (yeah, it's one bassy boi), but the B2 has more control in the low-end. The midrange on the B2 is thinner and cleaner. For me, the L9 has the advantage in the highs because of its sparkle, but that's more so personal preference. The B2 is also the clear winner in terms of technicalities. They're very different IEMs, but in the most objective sense possible, the B2 is the better IEM not even taking into account the price differential.

Test Tracks (just some of the ones I used)
  • Brooks and Dunn – Red Dirt Road
  • Ekali – Cage
  • IU – Blueming
  • Jason Aldean – Talk About Georgia
  • Keith Urban – Sweet Thing, Kiss a Girl
  • Kelsea Ballerini – Needy
  • Lee Brice – Love Like Crazy
  • Sabai – Million Days
  • SawanoHiroyuki[nZk] – REMEMBER, e of S
  • Taeyeon – My Voice (Album)
The Verdict

The more hours I put on the L9, the more I realize that it's in a bit of a weird spot. It doesn't seem to play especially well with any of the genres that I regularly listen to, sans perhaps EDM. It's neither an analytical IEM nor a laid-back IEM due to its booming bass and sparkly treble. There's also a lot of reservations that one should have about the L9's tonality - particularly the boosted bass response - and it's not the greatest technical performer either. For these reasons, I don't think it's competitive at its $550 asking price, and a couple of the select comparisons I outlined above are good examples of why.

And yet, the L9's not a bad IEM at all. In fact, it's probably my favorite IEM out of the Thieaudio lineup so far, although in all fairness I only lasted five minutes with the V14 before handing it back to its owner. To this effect, the L9's mostly a guilty-pleasure IEM for me. So while I can't really recommend the L9, I can't say I dislike it, and if the tonality sounds like something that would float your boat - then why not?

Score: 5.5/10 (Good)
Understanding my scoring: This is a personal, subjective assessment of an IEM’s sound quality. I don’t take into account any other factors, and it's relative to the absolute best sound I've heard. Take it with a grain of salt! I’m not going to lie; I have high standards. But I’m not telling anybody how they should hear something – it’s a reflection of what of me, myself, and I hear.
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Introducing ThieAudio
Thieaudio was launched in 2019 as a creative endeavor of Linsoul Audio. The goal of Thieaudio was to serve as a creative platform for gathering the best teams of engineers to inspire revolutionary audio products for audiophiles and professionals alike. For each project, we hand select the most innovative and renown engineers in his or her field to oversee the design, engineering, and manufacturing of the products. The first chapter, the Thieaudio Phantom, drew overwhelming praise from the international community and was even applauded as the new standard for planar magnetic headphones by some.
Gathering this momentum, we are proud to present the next chapter of Thieaudio - the Voyager and Legacy series. These new series of In Ear Monitors were created to bring about unparalleled sound performance that would rival the leading international brands.
The Voyager series was designed as the launch of Thieaudio’s pursuit in the realm of in-ear monitors, and features some of the most innovative techniques we have to offer. The Leagcy series takes the most trusted and established knowledge and designs available in the industry, and presents them in a refreshing and refined manner. We believe the Voyager series may be more suited for musicians, while the Legacy series may better fit audiophiles and music enthusiasts.
Focusing on three primary values - musical tuning, high-fidelity sound quality, life-like listening experience - Thieaudio’s new project aims to redefine the true potential of in-ear monitors for both enthusiasts and professional musicians. So we welcome you to step in, and open your ears to a world of audio like nothing before.

8+1 = Power
The Thieaudio Legacy 9 combines the technical prowess of balanced armatures with the full power of a 10mm Dynamic Driver. Utilizing eight genuine American Knowles and Danish Sonion balanced armatures, the treble range is effectively enhanced, bringing out all of the natural details and clarity of the music, as well as an elegant airy atmosphere that accurately reflects the studio and stage. The large dynamic driver brings about a full and impactful bassline that is sure to rumble the ears. We believe the Legacy 9 sets the bar for one of the best low-frequency performances out of all in ear monitors. However, our tuning style also reflects the need for a clean and balanced musical experience, thus emphasizing the vocal range to highlight texture and shimmer of both male and female voices. Our integrative 4-way crossover system coherently distributes all drivers to their respective frequency ranges, preventing overlap and phase inconsistencies. Highest quality drivers, masterful tuning, and skilled engineering sets the Legacy 9 as the highest competition for hybrid in ear monitors today. As the flagship model of the Legacy series, the Legacy 9 puts out a powerful, balanced, and captivating sound. We believe the Legacy 9 is among the best tuned in-ear monitors available today.

Exotic Solid Wood Housing and Faceplate
While power, warmth, and clarity define the musical quality of the Legacy 9, its appearance and build can be described as intricate and elegant. Every component is hand built, piece by piece using only the highest grade genuine solid wood. There are only a couple of manufacturers around the world offering full wooden shell and faceplate options, and these often cost (literally) thousands of dollars. At Thieaudio, we wanted not only the sound to be boutique, but the presentation and appearance of the Legendary series to be bespoke. Each monitor is hand carved out of select exotic solid wood, and this process alone takes an entire day to complete. Our skilled staff each have over a decade of experience building custom in ear monitors, and each unit is crafted unto perfection. Each earpiece is unique, and there is nothing on Earth that will look like it. You can rest assured knowing that your in ear monitor is safe to use, durable, and a masterwork of art.

Custom Ultra-pure 7N OCC Copper Cable
To maximize the sound quality of the Legacy 9, we have undergone extra expenses to hand-braid an 8-core ultra-pure 7N oxygen-free copper cable. This custom cable minimizes electrical resistance, allowing the sound to be fuller, more clear, and extend the soundstage. We also love how the copper contributes to the bass and midline, strengthening the full sound of the Legacy 9.