The Truthear Zero: Blue 2 was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links. The price of the Truthear Zero: Blue 2 is $64.99 and you can buy it from Shenzhen Audio.
Truthear Zero
Truthear’s Zero is a line of earphones made in collaboration with Crinacle, a renowned reviewer. Crinacle is the founder of In-Ear Fidelity, a website that features earphones and headphones measurements with a ranking system that is mostly based on these measurements rather than actual listening impressions. It’s been a while that Crinacle paused this project in order to found Hangout audio, a website for selling earphones from various brands, as well as his own CrinEar earphones.
The latest addition to the Truthear Zero series, that already includes the Blue and Red models, is the Blue 2.
Truthear Zero: Blue 2
The Truthear Zero: Blue 2 is a dual dynamic driver IEM that incorporates a 10mm driver to handle the bass frequencies and a 7.8mm one for the mids and the highs. The first is a solid silica gel suspension driver with composite liquid crystal dome and the second is an upgraded polyurethane suspension driver with liquid crystal dome. The Blue 2 utilizes a DLP-3D printing process for the cavity and a silicone capping technique, methods that are typically reserved for more expensive products.
The earphone features a redesigned cavity structure and a low-distortion frequency crossover with the aim to enhance the dynamic drivers’ conversion efficiency while allowing each speaker to fulfill its respective role.
You can read more technical information here.
Design and user experience
The ear-shells of the ZERO: Blue 2 are made from medical-grade resin material and are 3D printed by the renowned brand HeyGears. The Blue 2 inherits the design of the original model but it now features a redesigned faceplate and optimized nozzle size with adjusted supporting angles for a more comfortable fit.
The main body is adorned with glossy black finish and the faceplates bear a blue colored pattern that resembles leafs (or maybe insect wings – who knows) woven together. The ZERO: Blue 2 is a beautiful looking earphone that is not very bulky, it is quite lightweight and offers a comfortable wearing experience with decent passive noise attenuation despite the three venting holes in each earpiece.
Cable and accessories
The Truthear Zero: Blue 2 comes with a 2-pin detachable cable of decent quality. It is a two-strand copper and silver-plated coaxial cable with a rubber sheathing that is well made, doesn’t get easily tangled and has only mild microphonic noise. For $5 more you can order a second cable with a microphone and in-line controls.
The package also includes a nice carrying pouch made from synthetic leather, three pairs of silicone and four pairs of memory foam ear-tips. Inside you will also find a 3.5mm 5Ω impedance adapter that is used to boost the bass, as we are going to find later on.
Sensitivity
The Zero: Blue 2 has an impedance rating of 5.2Ω with 119.5dB/Vrms of sensitivity. It might look easy to drive but the source should be able to provide sufficient current at such a low load, something that not all portable USB DAC dongles can do.
Additionally, the earphones are sensitive to hissing noise so the source must be silent. For this review I have mostly used the FiiO KA15 and iBasso DC07PRO USB DAC dongles, sometimes with an aftermarket balanced cable.
Listening impressions
The manufacturer suggests using the earphones with the memory foam ear-tips for the best tonal balance.
The tuning of the Truthear ZERO: Blue 2 closely adheres to the Harman target curve with a couple of adjustments here and there, the most notable one being the addition of extra bass. This earphone is made for people who like a generously boosted bass and prefer a casual, warm and fun sound rather than strict tonal accuracy and transparency. Without going into a detailed frequency response analysis let’s just say that the ZERO: Blue 2 is not the best option for reference or critical listening but it sounds really exciting and enjoyable with a great variety of tunes.
The Blue 2 has great sub-bass extension and a plethoric low-end that does without much bleeding into the mids or overpowering the higher frequencies. The ZERO: Blue 2 is punchy and impactful, it will fill your ears with rumbling, weighty and undistorted bass. The technical performance is decent too, the bass is sufficiently fast and tight without lacking that much in control and precision. Layering and definition are acceptable for the category but not up to the task when the music tracks start to get really busy.
More listening impressions
The mid-range is surprisingly clear and well defined despite the emphasized mid-bass. It sounds present and articulate with enough harmonic variety and good tonal accuracy. The timbre is quite natural, the textures are rather weighty and lush, the music is lifelike and engaging. You can enjoy modern pop tunes with heavy bass lines without losing track of the vocals. The upper mid-range is slightly accentuated to gain the necessary energy and excitement to counterbalance the lows but sometimes it can be perceived as mildly fatiguing depending on the music and the user’s sensitivity in this area.
The treble perception depends on the ear-tips used, it is a bit smoother with the memory foam tips and will sound more prominent with the silicone. No matter the tips used, the treble is energetic and sparkling with a touch of gentle brightness. Clarity, separation and detail retrieval are good enough but the truth is that the Blue 2 is somewhat lacking in resolution and texture refinement.
The tonal balance is acceptable, the high frequencies are quite weighty and not thin but the timbre has a taste of artificiality. Raising the volume can make the treble more coarse and metallic, the Blue 2 is much more enjoyable at lower listening volumes.
The soundstage is intimate without much width or depth but it images sufficiently well, at least with pieces that are not too demanding. As an example, solo singers with their typical bands and small ensembles are realistically presented, however the Blue 2 can’t follow that well on larger scale works.
The impedance adapter
Instead of having interchangeable nozzle filters or crossover tuning switches, the Truthear ZERO: Blue 2 uses a 5Ω impedance adapter to raise the bass. This method is straightforward and simple but its main disadvantage is that it can’t be used with balanced cables so you are stuck with a single-ended source if you want to boost the bass.
The adapter significantly increases the bass from the sub-bass all the way up to the mid-range thus transforming the ZERO: Blue 2 into a bass-head IEM. The downside is that it messes with tonal accuracy, compromises mid-range clarity and makes the bass lose some control. Nevertheless the bass-head crowd doesn’t care much about tonal precision, so this is a nice freebie option that many people are going to use and enjoy.
In the end
There are dozens of other earphones at this price point that follow the Harman target curve. So the question to arise is why to choose the Truthear Zero: Blue 2 over something else, like say the Truthear Gate?
A simple answer would be because you are fond of this particular tuning variation of the Harman curve that has more emphasized bass while staying clean on the mids and the treble. You can also reach bass-head levels thanks for the included impedance adapter. Additionally, the Truthear Zero: Blue 2 is a beautiful looking, well made and comfortable to use earphone while it comes with a nice accessory pack, thus earning its place among the vast competition.
Copyright – Petros Laskis 2025.
+ Harman target curve with extra bass
+ Sub-bass extension and weight
+ Punchy and impactful bass with decent technicalities
+ Mid-range presence and clarity
+ Sparkling but not too brilliant treble
+ Impedance adapter that raises the bass
+ Lightweight and comfortable with good isolation
+ Well made and beautiful looking
+ High quality cable for the price and nice set of accessories
- Too much bass and lack of tonal accuracy
- Yet another Harman target variant
- Intimate and flat soundstage
- Not that resolving or refined
- Rather artificial sounding treble
- You must use the foam ear-tips for the best tonal balance
- The impedance adapter compromises clarity and technicalities
- Not that easy to drive
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