Fit and Comfort

Ah, and we get to the cause of my excitement. I have procured a set of tools to measure the frequency response curves for headphones and earphones alike, which includes an artificial ear mold based on a standard head used for this very application by certification agencies. The ear pulls double duty by also demonstrating the fit of the ThieAudio Legacy 5, at least as far as the right earbud goes, with the stock cable looping over the outer ear. I will also say that my own experience looks about the same as with the artificial ear, and the angle of the connector paired with the built-in loop of the cable is a much better experience than on the Ikko OH10.

Adding to this, I am happy to say that the size M foam tips paired with the rounder body and lighter weight made for an extremely comfortable listening experience. I switched over to the silicone and found it to be pretty much the same in comfort personally, albeit with a less-forgiving fit. Of note here is that the stem juts out further than average paired with the rounded sides, to where those with shorter ear canals may experience some discomfort with the stock ear tips. In that case, I'd recommend a double-flanged set of aftermarket ear tips, such as from SpinFit, which the silicone tips here might well be from given how similar they look.

Audio Performance

Audio Hardware

ThieAudio is using a crowded 5-driver system per earbud, with a proprietary 10 mm "nano-membrane" dynamic driver for the lows and bass on which not a whole lot of information is available. It's been used by the company on some of their other IEMs, including higher-end ones the Legacy 5 got the benefit of a trickle-down approach from. The dynamic driver is complemented by as many as four separate balanced armature drivers, starting with two Sonion drivers to tackle the mids and the start of the highs before two Bellsing drivers take over for the high end entirely. This 1 DD + 4 BA hybrid driver setup is not unheard of in the price range the ThieAudio L5 operates in, but you typically get a 1+1 or 1+2 setup from the more popular brands.

With a rated impedance of 23 Ω, driving the hardware is easy enough, no aftermarket amplifiers are required. That said, these will still benefit slightly from more power, although scalability is on the weaker side. DACs will always go a decent way in the audio experience, however, and a portable DAC/amp might well be part of your collection if you are considering IEMs and other audio solutions in the $150+ price range. Also, 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 on the other end, since you will have to use an adapter anyway. This is why I paired these with the FiiO E17 and Creative SXFI Amp, with the latter more out of curiosity on how the soundstage would be affected. If not on the go, space is less of an issue, but the 1.2 m cable might be a potential handicap if connecting to a PC as the audio source.

Audio Quality

I will preface this section by saying that I do not yet have a lot of wired IEM experience, with my general preference being wireless TWS earbuds and neckband earphones for the convenience on the move. So judge the following impressions with that in mind, as well as my general preference for a V-shaped sound signature emphasizing elevated bass and treble with recessed mids. I also generally prefer instrumental music over vocals, which complements the V-shaped profile. This will change soon enough based on what I am planning to do, however.


Here we go! It took some time to identify all the necessary pieces, order them with a language barrier in place, obtain the necessary software, and finally set up a reproducible testing methodology. It begins with an IEC711 audio coupler earbuds can feed into, enough to where you have decent isolation similar to one's own ears. The audio coupler feeds into a USB sound card along with the IEMs themselves, which in turn goes to a laptop that has ARTA running. I begin with an impulse measurement to test for signal fidelity, calibrate the channel output, and finally test the frequency response of each earbud separately. Octave smoothing is at the 1/6th setting, which nets a good balance of detail and noise not being identified as useful data. Finally, using a customized metal base, I test the right ear bud separately on the artificial ear mold that can be screwed into the IEC711 coupler for a look at a more realistic audio response.


Feel free to ignore the actual values of the Y-axis since I don't think an SPL conversion is appropriate with this much equipment adding to the measurement. What is really useful information is how the left and right channels work across the rated frequency response in the ThieAudio Legacy 5, or at least the useful part of it. The left earbud was separately tested from the right one and colored above to match the colors used by ThieAudio for both. I did my best in ensuring an identical fit for both inside the IEC711 orifice, so note how the right channel ends up having a slightly lower response in the low frequency (bass) as well as the highs (treble) compared to the left channel. In practice, you will not experience any tangible difference, especially as actual differences are quite small to begin with.

What we get with either is a very interesting tuning, one that is deliberately done by ThieAudio and borrowed from its more expensive offerings. There is an elevated bass across the frequency range, which ends up mostly uniform even considering the broad peak around 30 Hz. I am sure you noticed that the graph starts below 20 Hz, and I indeed got a signal all the way from 11.7 Hz on both earbuds. Past 30 Hz, there is a dip where the dynamic driver gives up and the Sonion drivers take over for the mids. In fact, I will say that this works out for the better since you still get a thumping bass but clarity with vocals and most instruments is retained. It is in the high range that things are not as complementing, however, with the Bellsing balanced drivers losing some treble extension with irregular dips past 8 kHz I did end up with a less-satisfactory reaction to, especially with female vocals. Also for those wondering, the expected dip happened well past 20 kHz and closer to 22 kHz. It's purely of academic note here since neither you nor I can hear anything at those frequencies ever.


With the artificial ear mold of the test setup, I used an orange color to show that it is still the right channel in red (also there as a control), but different from it. In fact, this result pronounces the fit variable even more since how well the ear tips fit your specific ear shape matters, and this is still more representative than the coupler by itself, so we proceed. The lows and mids are suppressed slightly compared to before, and the highs elevated further to where I had to re-scale the Y-axis slightly to show everything. As before, click on the images for a better look.

Perhaps it is a case of my directly comparing it to the only other IEM I reviewed before, but I did find the Ikko OH10 with the Knowles BA driver more appealing with female vocals, and string instruments in particular, but the ThieAudio Legacy 5 did a fantastic job with the bass-to-mids transition and kept it going, so much so that I rate it higher than the OH10 overall. I felt the soundstage is slightly inferior to the OH10, though, but it benefited more from the Fii0 E17 and a couple of other DAC/amps than the Ikko offering. There is enough to merit a halfway decent amplifier, and onboard audio solutions on decent motherboards will do the job paired with a DAC to help clean up the source further.