Fit and Comfort

Seen above are both the white and black size M silicone ear tips that come with the ThieAudio Legacy 2, installed on the right ear bud and inserted into an artificial ear mold. I have averagely sized ears, and the ear mold seen above about perfectly represents my own experiences. Size M silicone tips are my go-to for testing since foam tips are not included by some, and both size M silicone tips gave a pretty similar fit to where the difference is more to do with resistance and conforming to a particular shape, with the white tips slightly softer than the black ones. The size of the ear buds is about average, and the design should be very comfortable for most people courtesy the soft curves gently caressing the concha and antritragus. At under 6 g each, these are very lightweight as well, further adding to the comfort factor. Once inserted properly, a good seal provides a substantial degree of noise isolation. ThieAudio even rates it at ~26 dB of passive isolation.

Audio Performance

Audio Hardware

ThieAudio is making a big deal about the audio hardware that went into making the Legacy 2 IEMs, claiming the competition tends to cheap out on the more budget-oriented solutions. This is generally true, and ThieAudio is backing its claim by debuting a brand-new 10 mm dynamic driver that is being trialed here rather than on a higher-end set. This new beryllium driver should interest many who have been keeping up with the use of beryllium in dynamic driver diaphragms, as its increased stiffness makes it respond to electromagnetic impulses very quickly. The aim is to "produce a powerful sub-bass impact" with a transition over to the mids before the cross-over to the upper mids and treble, where the tried-and-tested Knowles ED29689 balanced armature driver takes over. The overall tuning is meant to be that of a "performance-grade monitor," which is a bold statement to make.

Driving the hardware takes more than with your average IEMs, with a rated impedance of 32 Ω and slightly higher than average sensitivity of 108 dB/mW. A DAC/amp intended for high sensitivity earphones is not a bad idea thus, but harder to justify for the price tag of the Legacy 2 unless you already have one or plan to get these alongside other listening solutions. The lack of a 3.5 mm audio jack for most phones these days is another reason to consider a DAC/amp that takes digital input and provides a 3.5 mm jack since you will otherwise have to use an adapter anyway, or even a dedicated DAP. If not on the go, space is less of an issue, but the relatively short cable might be a potential handicap if connecting to a PC as the audio source.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that ear buds can feed into to where you have decent isolation similar to real ears. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the sound card. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/6th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the ear mold that fits to the audio coupler for a separate test to compare how the IEMs fare when installed in an ear geometry and not just the audio coupler by itself. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, just within our own library of measurements. This is also why I am trialing just omitting the raw dB numbers altogether, noting instead that I had set the SPL to 75 dB in REW and each tick in the Y-axis is 5 dB (I've since updated the testing further in subsequent reviews to have the numbers again with a proper calibration having been done). What is more useful information is how the left and right channels work across the rated frequency response in the ThieAudio Legacy 2, or at least the useful part of it. The left earbud was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two are identical in the bass and upper mids. This also points towards where the cross-over happens with the Knowles BA taking over since the right channel ends up being slightly off but still within +/- 1 dB most of the way, until past the ear canal resonance compensation hump at ~4 kHz where the difference gets higher.

In fact, the same continues with the test using the ear mold to represent an ear and cheek simulator and an example set of ear canals. As expected with the ear canal in the way, the frequency response drops in the lows and mids, and the treble response actually gets more consistent, which also matches my own listening experience. So this is good news for listeners since it usually ends up the other way around, with the tuning done for the more idealized artificial ear simulator in the budget range of the Legacy 2 instead of an ear-and-cheek simulator. I will also mention that there was no discernible break-in period or effect, so there is overall good reproducibility and consistency since the average response for each channel is also essentially the same across the three repeated tests.

ThieAudio made a big deal of its new beryllium dynamic driver, and I have to say it might have been a case of marketing going overboard. The sub-bass response is quite nice with plenty of energy and clarity, but there is a consistent drop in elevation when going to the mid-bass and on to the lower-mids to where people might have been expecting more. I certainly did, and whether it is the tuning at play or the driver itself, you end up wanting more in the upper-mids in particular. Certainly not for bassheads, but the way I am seeing it is that the Legacy 2 did not commit properly to the claim of natural mids. I will grant that the company mentioned nothing about pure bass impact, rather specifying it was definitely more on the sub-bass, which is true. As seen above, the transition is smooth, but goes on too long for those who want a more neutral response, or not long enough for those who want more punch.

Once you do get to the mids, things are very good in providing what was promised. There is indeed a fairly neutral response with plenty of accuracy to appeal to many who prioritize listening to vocals and instruments as intended by the recording artist. Male vocals are relatively recessed, so this is where I would suggest bumping it up slightly via EQ. Don't plan on using EQ throughout, though, since the Legacy 2 does not scale well with it. I suspect the lack of a second balanced armature, as with the Legacy 3, forced ThieAudio to have the single dynamic driver cater to the lows and mids, and all this made me think of was what an updated L3 with the new beryllium driver could do. Balance continues to be the name of the game with the cross-over to the actual BA, with the Knowles ED29689 beginning with the expected hump to account for inner-ear resonances given this is an IEM. It still continues to be neutral here, although accuracy is marred somewhat by that shoulder peak between 4–5 kHz that can affect consistency in classical and opera music. There is enough energy here to continue on with a stable transient response for the treble range, providing high resolution and an airy response for string instruments all the way past 10 kHz. Imaging is decent considering the hardware, although soundstage does take a hit since there is a muddier response than I'd like in the lows and upper mids in particular that does not let the various sound sources breathe freely.

Comparison to other IEMs

I had originally planned on comparing the ThieAudio Legacy 2 with the BLON BL-A8, which is quite close in pricing, as well as the TinHiFi T5 given the lack of any other sub-$100 set of IEMs here. You can clearly see a surprise entry replacing the latter since I ended up testing another set that is going to be reviewed soon after in the form of the sub-$50 Tripowin TC-01. I am going to make a potentially controversial call here and say that if I don't know of your specific music tastes, the BL-A8 is the one I would recommend. The BL-A8 is a clear-cut case of aesthetics first, but will also appeal to the general public far more than the ThieAudio Legacy 2 courtesy all the inexpensive wired/wireless earphones that prioritize a bass-heavy response with a single dynamic driver. The BL-A8 also loses out massively when it comes to balance, however. If you know what you are looking for and music genres that complement vocals and instruments are part of it, the Legacy 2 is for you. It is the most balanced of the three, with the TC-01 giving up any pretense of anything other than an extremely V-shaped tuning with extremely recessed mids and heavy bass. Imaging is better with the Legacy 2 as well, although soundstage remains a coin toss between it and the BLON BL-A8. None of the three are especially good with treble, but I would once again give the edge to the BL-A8 for more universal appeal and the Legacy 2 for higher accuracy.