HiFi Boy is a new Chinese company that started not too long ago. They produced the HiFi Boy OS V3 as their first in-ear monitor. It has a popular driver configuration – 2 Balanced Armature and 1 Dynamic. I would like to thank Penon Audio and HiFi Boy for this review unit. At the moment, you can purchase the HiFi Boy OS V3 from .



  • Drivers: 2 Balanced Armature & 1 Dynamic Driver (Ultra-high frequency Balanced Armature + high frequency Balanced Armature + 7mm strong magnetic composite diaphragm Dynamic Driver )
  • Impedance: 19 Ohm
  • Sensitivity: 109 dB
  • Frequency response 20Hz-20KHz

Unboxing & Accessories

The HiFi Boy OS V3 comes in a matte black package that has the HiFi Boy logo printed at the front. After opening the package, there is a HiFi Boy carrying case with the brand name printed on it, gold-plated headphone adapter and a flight adapter. Inside the carrying case, you get eartips and the iem itself.




IEM Build & Design

The OS V3 has a glossy black surface to its faceplate and shell. On the faceplate, there is HiFi Boy logo printed on it in silver colour. The shell is made out of plastic. The iem is not heavy at all. There is a vent at the side of the iem shell. The nozzle is angled with 2 bores. There are no L & R markings on the iem to differentiate between left and right.





Cable Build & Design

The cable is 4 core braided and it is made of silver plated copper. It uses mmcx connectors with a transparent housing. On the mmcx connectors, there are L & R markings to differentiate between left and right respectively There is a memory wire area section in which the cable is enclosed in a transparent heat shrink tube. However, it is still very flexible. The chin slider and y-splitter has a transparent housing. Lastly, the jack is 3.5mm rhodium plated right angled. It has strain relief and a transparent housing.


Sound Analysis


The OS V3 has a well extended sub-bass with a quick rumble. The mid-bass is engaging with a nice slam and dynamics is being boosted. The extra punch provided by it accentuates the overall bass. Bass texture is rather smooth and it operates in a clean approach. The decay is rather quick and on the point. Each bass note is presented with a clean and precise hit. I find the bass to be very engaging. There is a good combination of texture and speed which results in a harmonious presentation. The transition from the lows to the lower mids is rather effortless.


The midrange on the OS V3 is slightly v shaped and you will not get the thick and lush mids. Instead, it operates on the clean and transparent approach. The lower mids on the OS V3 does not have a lot of quantity and there is no hollowness in male vocals. The upper mids are slightly forward and there is no veil at all. Female vocals are sweet sounding. Overall definition on the midrange is good with details being presented. There is an energetic feel to it.


The treble is extended greatly and there is body to it. Although it does not have a lot of body, there is still weight in its presentation. There is no sibilance and harshness. The lack of grain makes the treble soothing to listen to. Air rendered has a good amount of quantity and the presentation is not very heavy sounding. Crisp has a good definition and there is no congestion in the sound. There is a high level of details retrieval.


The OS V3 has a natural expansion in its width to reduce congestion. Positioning of vocals and instruments is accurate and there is good separation. The depth is not close in with a good amount of space at the front. I feel the soundstage on the OS V3 is great.



HiFi Boy OS V3 vs iBasso IT03

The OS V3 has less sub-bass quantity and extension than the IT03. The sub-bass reproduction from the IT03 packs both quantity and extension. OS V3 has a good sub-bass but just cannot catch up with the IT03. The mid-bass on both is fairly similar and there is a good slam. Bass texture on the OS V3 is slightly more smooth and there is mastery on both. Decay on the IT03 is slightly quicker with a faster rumble that improve the dynamics and engagement. The bass note on the IT03 is presented with more finesse and the bass from the IT03 is on a higher level than the OS V3. In terms of lower mids, the OS V3 has slightly more body and male vocals are being expressed with more thickness without sounding hollow. For the upper mids, the IT03 appears to have an edge with more forwardness and female vocals benefit from it. In the treble section, OS V3 has more control and the mastery is shown. The energy from the IT03 is more existent. There is no sibilance and harshness on both. In terms of soundstage, the IT03 has the better width while the depth of the OS V3 has more space as it is not too close in. Vocals and instruments positioning is better on the IT03. Resolution of IT03 is better.

HiFi Boy OS V3 vs Oriolus Forsteni

The OS V3 has more sub-bass than the Forsteni and the extension is as deep as the Forsteni. The Forsteni hits slightly harder and there is more impact. Mid-bass on the OS V3 has a heavier weight and there is a better slam. On the Forsteni, it is more clean and clinical. Decay on both is very similar and a quick rumble is being expressed. The texture of bass is smoother on the OS V3. Moving on to the lower mids, there is more body on the OS V3 and it does male vocals justice. On the other hand, the Forsteni does not express male vocals as well as the OS V3 since quantity is lacking. For the upper mids, the Forsteni has more forwardness and crisp. Female vocals sound particularly well here. Treble articulation is more accurate on the Forsteni. Details retrieval on both is similar. Both operates in a rather similar approach. For soundstage, they have similar width and depth. Layering and separation is approximately the same. Resolution is at the same level.

HiFi Boy OS V3 vs Campfire Audio Dorado

The Dorado has more sub-bass quantity than the OS V3 but there is more extension on the OS V3. There is more bass definition in the Dorado bass reproduction. Mid-bass on the Dorado has more slam due to more weight. The mid-bass presents itself in an authoritative manner. Bass texture on the OS V3 is more smooth. The level of finesse on the Dorado is more matured but I feel OS V3 is a more engaging listen due to its fun approach. The lower mids of the Dorado is thicker while for the upper mids, there is more intimacy on the OS V3. OS V3 has an organic feel to its top end. In terms of soundstage, the OS V3 has a good width with a natural expansion. There is more depth in the Dorado. Vocals and instruments positioning on the Dorado is more accurate. Resolution of Dorado wins slightly.


The HiFi Boy OS V3 marks HiFi Boy debut in iems. It provides an alluring bright sound that has treble flair. Female vocals are portrayed in a sweet manner with a good level of details retrieval. There is good build quality on the OS V3 and excellent fit. Overall, the OS V3 is nothing short of impressive for a company’s debut iem.