Fiio FF3S

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Fiio FF3s

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Sound Quality 8
Bass 9
Midrange 8
Highs 7
Soundstage 8
Technicalities 7
Design 8
Build Quality 9
Comfort 9
  • Neutral Sounding Signature
  • Large and deep soundstage
  • Excellent Punchy Bass
  • Solid Build Quality
  • Very Comfortable & Lightweight
  • Modular Cable & Interchangeable Plug
  • Peaky Treble, not for Treble Lovers
  • Not the Best Technicalities
  • Stiff Cable


FiiO has gained acclaim for its earbuds that seamlessly blend outstanding audio quality with stylish aesthetics. Known for their exceptional single dynamic driver (DD) setup, FiiO’s earbuds have consistently impressed critics with their superb tonal quality, clarity, and smooth bass texture. The FiiO FF3S represents an upgraded iteration of the FF3 flat-head earbuds. With an entirely redesigned aluminum-alloy cavity structure, the FF3S boasts enhanced sound performance while maintaining an ultra-lightweight and attractive design, weighing just 3.9 grams per ear shell, ensuring comfort during extended music sessions. Employing a Dual-Drum cavity design and a bass-enhancing acoustic-flute structure, the FF3S provides a remarkable auditory experience. The “Drum” cavity design optimally utilizes resonances to deliver rich and well-balanced bass, which, in turn, enhances the mid-range with added depth and natural thump.


Driver configuration: 14.2 mm beryllium-plated dome + polyurethane gasket diaphragm dynamic driver
Frequency Response: 20Hz-20kHz
Impedance: 45 Ohms @1kHz
Sensitivity: 105dB (1kHz@1mw)
Max Input Power: 100mW
Plugs: Included 3.5mm (Single-Ended)
4.4mm (Balanced) Twist-Lock Swappable Plugs
Connector: 0.78mm 2-Pin
Cable: 152 Wires High-Purity Silver-Plated Monocrystalline Copper
Cable Length: About 120cm
Weight: 3.9g Per Earbud (Excluding Cable)

Fiio FF3S


  • 3x Pairs of Balanced Foam Tips
  • 3x Pairs of Bass Foam Tips
  • 6x Pairs of Donut Foam Tips
  • 3x Pairs of Large Silicone Rings
  • 3x Pairs of Medium Silicone Rings
  • 1x Pair of Silicone Wing Hooks
  • Detachable Modular Cable [3.5mm & 4.4mm]
  • Plastic Carrying Case


The cable, which is detachable and of excellent quality, is fairly thin and highly flexible, striking a good balance between being lightweight enough to not strain the earbuds and having enough weight to prevent tangling. At the cable’s end lies the latest generation interchangeable plug. While I appreciated the previous design, this one surpasses it. FiiO has successfully crafted an interchangeable plug that maintains the size of a regular one. Moreover, the mechanism feels incredibly sturdy, rendering it practically identical to a standard plug.

However, there is one issue: the cable is quite stiff, causing some discomfort.

Fiio FF3S
FF3S & KA13 Combo


The FF3S resonates with a rich, bassy L-shaped tonal profile, enveloping listeners in its warm and velvety embrace, perfect for indulging in extended musical journeys, unlike its thinner, more taxing counterparts. The quantity of mid-bass tends to be flat and neutral and may not meet the expectations of bass enthusiasts. There is a slight mid-bass bleed noticed when listening to hip-hop tracks like those by 21 Savage, Doja Cat, etc.


The midrange on the FF3 is noticeably recessed, yet it boasts a substantial amount of strength and texture, lending vitality and enjoyment to instrument rendition. Vocals exhibit a pleasing quality, with both male and female vocals offering abundant detail and a genuine, lifelike presence. Transients also exhibit commendable performance.

Using different foam can influence the character of the midrange. The Bass Foam tends to impart a warmer tone to the mids, whereas the Donut Ring Foamies enhance clarity and airiness in the midrange.

Fiio FF3S
FF3S & Pegasus SG1 Combo


The high frequencies with good extension and details, surprised me with their level of separation. The treble boasts remarkable energy, balance, and smoothness, but could benefit from a slight increase in body for the treble notes. Moreover, the timbre, akin to the mid-range, impresses with its nuanced thickness in the cymbals, striking a perfect balance for a lifelike experience. The well-defined and spacious treble never veers into aggression, offering transparency, resolution, and precise stage positioning that impeccably separates it from the midrange. In summary, clarity is decent, and the treble performance is remarkably realistic, and well-defined, leaving a lasting impression.


The staging abilities of the FF3 are notably strong, surpassing average performance for its price range. It offers ample width and height, enhancing the overall listening experience. The separation is impressive, offering excellent stereo imaging and positioning characterized by sharpness and focus.

The FF3S is very natural and excels in detail, boasting exceptional overall resolution and transparency. Its impressive micro-detail capability contributes to a lifelike timbre.



Fiio FF3S

The original FF3 comes with a non-detachable cable, while the FF3S offers detachable options. However, the detachable feature of the FF3S isn’t practical for me because it doesn’t use standard 2-pin plugs; therefore, you can’t interchange normal 2-pin cables. For instance, I have [ $10 – TRN EMA ] with 2-pin plugs, and I can easily swap them out with other 2-pin cables without any issues. If Fiio considers incorporating similar plugs for their future Flat-Earbuds, it would be highly beneficial. Additionally, as I mentioned earlier, while the cables provided are of good quality, they are stiff and uncomfortable.

The FF3 is heavier due to its steel construction, which led to ear fatigue during longer sessions. In contrast, the FF3S is much lighter and far more comfortable to wear.

Overall, the FF3S enhances its predecessor, with more neutral and analytical tunings, along with improved resolution and reduced bass. The FF3S demonstrates good technicalities and treble extensions. While the FF3’s bass is deeper and more powerful, but FF3S excels in bass quality. I prefer the FF3S for its clearer, more balanced, and versatile sound signature.


Fiio FF3S
FF3S vs DX6

The DX6 prioritizes mid-bass over sub-bass, lacking the deep, rumbling quality found in sub-bass frequencies. It emphasizes mid-bass punch and slam, ensuring adequate dynamics in the lower range. However, individuals who favor strong bass might not prefer this particular set.

The DX6 is more mid-centric, offering vocals that sound natural with excellent texture. While the DX6 boasts a spacious soundstage, the FF3S surpasses it in this aspect. One of the main drawbacks of the DX6 is its lack of bass, for bass lovers, the FF3S is the preferred choice.

Overall, my personal subjective preference – I prefer FF3S.


Fiio FF3S

The FF3S is truly enjoyable to listen to. Sometimes, I prefer earbuds over IEMs. Additionally, people who appreciate listening to speakers might prefer these over IEMs. Its sound presentation is incredibly musical and immensely enjoyable if not outright fun. The tuning provides tremendous enjoyment with a fine balance and good technical performance, particularly in detail and resolution. The bass of the FF3 is exceptional, boasting impressive physicality, texture, and detail. It is complemented by clear and spacious mids, along with a delightfully smooth treble that extends gracefully. Under $100 that’s the real deal.

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