Fearless Audio S4

Before starting this review, I would like to share technical aspects and package details.

Also, I would like to thanks to Penon Audio for this great opportunity. Here is the S4’s link: https://penonaudio.com/fearless-audio-s4.html



Technique Features: 4 BA Drivers, 3-way Crossover, 2 Sound Tubes

Drivers: Micro Knowles Balanced Armature Driver *4, Including Sonion Dual Bass BA Driver*1, Knowles Mid-Frequency BA Driver*1 and Knowles Treble BA Driver*1

Sensitivity: 114dB/mW

Impedance: 32 Ω

Frequency Response: 15HZ-20KHZ



Package Details:

Fearless S4

Plastic Cover Case

6 Pairs Foam Tips

6 Pairs Silicon Tips

Warranty Card

Cleaning tools


Test Equipment:

Lotoo Paw Gold Diana

Opus #1

Astell & Kern AK120



Package, Design & Isolation;

Fearless S4 comes with a simple yellow cartoon box. There is a plastic cover case, earphone, tips, warranty card and everything that comes inside of the black cover case. Plastic cover case is very similar to 64Audios’ case, but it differs its inside design and size. The case looks a bit flimsy but it is doing its job, protecting! There is a velvet material all over inside and it keeps your earphone safely and protect from any possible scratches. Lots of silicon and foam tips come with S4, so you can find the best for your ears.

S4 is really good building IEM, and pinkish translucent color is so beautiful. There are tons of other color options that you can select, and also you can customize your faceplate like CIEM. Silver Fearless print and logo look awesome. There is absolutely no flow, bubble or any other defects on the body. It is absolutely looking gorgeous, I’m pretty impressed by the build quality. I can call small for S4’s size, it is not big and it fits easily into ears. Also, long nozzle and ergonomic body shape provide an awesome fit. S4 has detachable 0.78mm 2 Pin socket, so you can replace it for any other cables you want, but stock cable is already great. It seems like aftermarket cable and looks and feels premium. This might be one of the best stock cables I’ve ever seen in this price.

S4 provides really good seal in the ear, it is very similar with Fibae 2 in terms of shell design. I’ve medium size ears and it fits like a glove. It is so comfortable and there is absolutely no pain for long listening. I like silicon tips and it is already providing a great isolation. You can always get a better isolation with foam tips as well.



Sensitivity and Power:

S4 doesn’t require powerful amp, so you can use with your any source without any driving issue. For example, iPhone 8 has quite enough power to drive S4. There is a very slightly hiss with my Lotoo Paw Gold but I’m talking about really small amount, so it shouldn’t be a problem with your source. Unless you have a horrible hiss maker source.



Sound Type:

S4 has a slightly V-shaped sound character. It has prominent high frequencies with strong, deeper bass and also has very good extension on both frequencies. Middle frequencies are slightly laid back into the overall spectrum but cannot be said it is fully laid back. Price/performance ratio is pretty high and it is seriously good earphone for its retail price. The soundstage is spacious enough for an airy and comfortable listening. Of course, V-shape sound character has a big role of here. The Fearless S4 is an earphone with a high level of dynamism and a pleasant listening experience with powerful bass and clear treble overall.



Upper frequency is one of the best areas on S4. According to this price band, the treble extension and detail level is quite high. It also performs extremely well as the resolution. Lots of background details in the music can be heard easily. Also, S4 is very successful in instruments separation. It is quite easy to make distinction in the music with stringed instruments. The treble is prominent but it never becomes uncontrolled and harsh. Fearless Audio made a really great tuning in this regard. The treble is not too strong and sharp, and it makes easy to listen. Also, does not give any sense of fatigue in long listening. It is performing well in terms of speed and it is nicely handling in fast passages. I tested with some of metal song even I don’t like metal, I didn’t feel it loses its control. But if it had a bit too much in quantity, things could get worse I believe. The sound of the treble does not feel unnatural or artificial, it is quite easy to understand that, especially on guitar solo music. Its timbre is natural and soft. However, it is not successful as a dynamic driver in terms of naturalness, but still it is very successful for a balanced armature driver. There is absolutely no veil over the upper frequencies, they do quite clean and clear presentations. In general, I can easily say that I like the performance of the upper frequencies. Even better than the price tag it has.



Mid frequencies are just a little laid back. Since the S4 is generally a fun sound earphone, therefore there is some coloration in the mid frequencies. For this reason, I would recommend that people looking for flat and neutral headphones should have to look elsewhere. Mid frequencies have a very pleasant tone in the guitar parts as like in the treble. The warm and smooth tonality feels natural and relatively organic. I’ve listened to jazz tracks and album with S4, and I think it might be the best for jazz music that I enjoyed the most. Of course, it is also quite successful for other genres, but I like to say that I enjoyed jazz with a different way. The mid-frequencies are slightly bodied and relatively colorful, so the instruments play one level thicker but I am not complaining about it. That’s what gives the sound its naturalness. The only issue that I will criticize is the positioning within the soundstage. The instruments are slightly behind the vocals, and I think that breaks the harmony of the music. It’s not that bad but I’d like to hear all instruments and vocals with coherence. At this point I found the positioning a little wrong. Mid frequencies are laid back, but vocal presentation is slightly forward overall. I like both male and female vocals. I don’t know is this the reason that I listened lots of male vocals, but I found male vocals more successful than women vocals. Women’s sounds are a little thicker than they should be. In general, I liked the mid frequencies, but I still think that the mid frequencies are not the best part of S4.



The S4 is an extremely successful earphone for lower frequencies. The Sonion dual bass driver is quite successful in this regard, and of course good job for Fearless Audio for its tuning. However, the S4 has not bass-head level of bass, but they are certainly not bass light too. The amount and intensity of the bass is enough to give pleasure in EDM genres. Overall bass is coming from mid-bass area, but they are also able to reach deep enough in the sub-bass. Bass frequencies are nicely controlled and tight, it is similar to Fibae2 in this regard. Resolution and detail level are also great. I think S4’s favorite frequencies are the bass for me. It has very good performance according to its price. It has more natural and stronger bass than some dynamic drives earphone on the market. It is taking the advantage of the armature drivers speed and tightness and adding some weight. Frankly speaking, S4 performs better than the 400- 500-dollar band earphones I’ve listened to. The dominant presence of the bass adds dynamism and rhythm to the general sound and it makes prat is pretty high. Only down side of the bass is sometimes exaggerated a bit with some bassy music. This does not bother me too much because the S4 has fun sound character in general. Overall bass performance is absolutely delicious for this price.



Due to the S4’s V-shape sound character, its soundstage is average wide. It is not super wide and deep, but spaciousness and airiness provide a comfortable listening experience. It is easy to hear where the instruments are located. The background of the S4 is quite dark and clear but it could be better.



Fearless Audio is very fresh audio brand and they have already released many earphones model under from their hood. S4 is their entry level IEM and its performance are better than some entry-mid level IEM’s on the market. I believe Fearless Audio is very successful with their highest model too. S6 Rui and S8 seems very promising. I can easily recommend S4 for people who look for fun and detailed sound signature with big bass and prominent detailed trebles. Built quality is also another great thing about it. S4 is in the budget side, so if you are looking IEM for 200-300 price band, absolutely don’t ignore it.

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