The sound impressions were formed with the 1-2 tuning setup. That means the left switch is closed so there’s no additional bass. The 2nd switch is opened for better and more defined mid reproduction. I left the switches on that state for the whole time. That’s why I don’t like tunable IEMs anyway because once you find the sweet spot, the tuning feature is useless because you actually never change it.
The Thieaudio Legacy 4 is a fresh-sounding, clean, energetic, and a bit bright monitor with a spacious presentation. It also has good dynamics, tonality, and resolution. Its bass has good pace and kick, its mids are dynamic and resolving, and its treble is quite splashy and bright. So I can say that Legacy 4 has great energy and dynamism.
The Legacy 4 has a controlled bass response with good impact and rumble. The dynamic driver is not dominating in any way, but it makes its presence felt when needed. It has good mid-bass and sub-bass balance, so it doesn’t feel too v-shaped with a fat sub-bass response. The bass performance is very satisfying for this price.
Lows have good texture as well and they have a good pace with great control. I really liked the bass presence and quality of the Legacy 4, simply because it can make things fun while not being overpowering. Lows are very tight, dynamic, and nicely balanced out.
So overall the L4’s bass presentation is very impressive and of the best in its price range, especially in terms of tightness, texture, control, and definition. This dynamic driver is excellently tuned indeed.
Mids have good resolution and transparency with fabulous clarity for the price level. The instruments and vocals are very clean and they have a good definition. It doesn’t sound meaty however so don’t expect a full-sounding mid reproduction. The L4 is a bit thin in that regard, so the mid-range is a bit cold and tinny sometimes. However, this helps to get a breathy and roomy presentation simply because the mids don’t fill up the whole stage.
This is a trick that many companies use, and it all depends on your preferences really. I prefer warm and fuller sounding IEMs for my daily use, so I’m not particularly a fan of this presentation. But I do understand where Thieaudio is coming from. It’s a difficult task to create a great headroom with thick and full-sounding mids with a distinctive mid-bass section. So this is a very useful tuning solution to create more space in the staging department.
And yet, the L4 has more positives than negatives here. Especially the level of detail and resolution are very impressive as a whole, and of course, mids are no exception. The vocals and instruments are tremendously clean, crisp, and energetic with excellent dynamism. The position of the mids is very realistic in the stage when the tuning switch is one, and the vocals are especially good with the L4.
Treble is once again very energetic, crisp, and dynamic. The excellent detail retrieval is also present here so you can hear every little detail in the song. The overall resolution success serves the L4 very well once again, making the treble sound well defined with great extension.
The most impressive thing here though is the level of detail. Sure, the L4 has articulated and well-extended treble, but it’s also extremely detailed for the price. Of course, this is proportional to your source device as well, but it’s impressive no matter what device you use it with. I remember the times where this was just possible with high-end stuff, but now it’s available to the masses.
The one problem is that the L4 sometimes gets a bit hot in the treble section. There’s nothing like a very obvious sibilane or ear-piercing treble response, but it’s a bit too bright and energetic at times. Depending on your source and overall preference, this might be an issue or not. It works great with electronic music for instance since you feel the energy and the emotion, but with some other genres, it doesn’t work perfectly.