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Headphoneus Supremus
One for the bass-lovers!
Pros: Superbly exquisite accessory line-up
Detachable modular cable for balanced and single-ended sources
Solid build
Well-fitting and lightweight
Great bass quality and quantity from a lengthened acoustic tube
Smooth upper frequencies, sibilant-resistant
Good soundstage
Natural timbre
Cons: Proprietary cable
May require amplification to scale better
Not for trebleheads
Tinge fuzzy in imaging

I bought the FF3S from Aliexpress at a discounted price. It can be gotten here (no affiliate links):

FF3 11.jpeg

  • Driver configuration: 14.2 mm beryllium-plated dome + polyurethane gasket diaphragm dynamic driver
  • Impedance: 45 Ω
  • Frequency response: 20 Hz - 20 kHz
  • Sensitivity: 105 dB
  • Cable: 2-pin, 0.78 mm; silver-plated monocrystalline copper; 4.4 mm and 3.5 mm termination modules available
  • Tested at $89.99 USD

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Other than the earbuds, these are included:
- 6 pairs of donut foams
- 6 pairs of full foams
- 1 pair of silicone wing hooks
- 3 pairs of silicone rings (L)
- 3 pairs of silicone rings (M)
- Cable
- 2 modular plugs for 3.5 mm and 4.4 mm termination
- HB11 carrying case

The accessories are almost perfect for the coin, and honestly, I've not seen a better accessorized earbud packaging in my audio journey so far.

FF3 1.jpeg

Two types of foam covers are included - the full foams increase warmth and bass, whereas the donut ones tame the bass a bit and let the mids shine thru better.

I also appreciate that Fiio has added a multitude of silicone rings and hooks, which will assist in fit and grip. Do explore the various permutations - double foams or silicone ring + foam is an option - to see suit what your comfort and sonic preferences.

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Fiio has included a 2-pin silver-plated monocrystalline copper cable, which is detachable, unlike the predecessor FF3. On the distal end we have 4.4 mm and 3.5 mm termination modules available, thus allowing the FF3S to be paired with various single-ended and balanced sources, which is a nice touch.

Removing the modules involves screwing it off the cable, and locking in the new one in place. Align the inner dot of the cable to the groove of the module and you are good to go.

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The cable is sheathed with German-made TPU, which is advertised to reduce hardening and to improve suppleness. It also aids in getting rid of microphonics - indeed there is none noted here - and there is a chin cinch for added grip during usage. The left terminal has 3 dots for guidance, which is useful for those with visual impairment.

Unfortunately, this cable is proprietary, and aftermarket cables cannot be paired with the FF3S, unless one shaves off the edges of the cable terminal. Sadly, this is a tick against the FF3S, and I'm sure consumers would have liked Fiio to provide a standard 2-pin or MMCX detachable housing so that we could use our favourite aftermarket cables or even BT adapters.

FF3 2.jpeg

Last but not least, we have a HB11 storage case ( Made of tough plastic, it is hard enough to withstand compressive forces. It features an innovative lego concept, so additional cases can be stacked on top of it.

There is a handle for ease of use - it operates like a sock drawer - and the transparent walls allow one to easily identify the contents. The HB11 is space-sparing, with a thickness of 2 mm for the walls, and it weighs 118 g, and measures 116 x 72 x 39 mm.

The rest of this review was done with the stock cable and stock full foams. No aftermarket accessories were used, so as not to add any confounders to the sound.

FF3 7.jpeg

The FF3S is fashioned from aluminum alloy, with a matte finish and a golden triangle motif faceplate. With each earpiece weighing a mere 3.9 g, they are almost half the weight of the predecessor FF3 (some earbud enthusiasts complained about the original's FF3 heavy weight!).

FF3 14.jpeg

The ergonomics are thoughtfully designed: we have a long slender stem, which nicely balances the CG of the housing, to snuggly fit in the intertragal notch of the ears. I did not encounter any discomfort despite using the FF3S for marathon listening sessions.

FF3 9.jpeg


At the heart of the FF3S, lies a 14.2 mm beryllium-plated dome + polyurethane gasket diaphragm dynamic driver. This contains an ultra-fine copper Daikoku voice coil, which is only 0.0033 mm in diameter!

Beryllium is a light material with a high modulus of elasticity, which in theory, allows the driver to be kept low in weight, yet with an extreme rigid core. This is marketed to furnish rapid transients with negligible distortion.

Fiio bass tube.JPG

Another interesting concept is Fiio's use of a deliberately lengthened flute-like tube, which increases sub-bass quantity. This is because higher frequency sounds are dissipated first in a longer acoustic tube, and on actual listening, the FF3S is indeed a very bassy transducer.


I tested the FF3S with the following sources:
- Apple dongle
- Cayin RU7
- Fiio K11 DAC/amp
- Fiio KA13 dongle
- Hiby R3 Pro Saber 2022 DAP
- Khadas Tone Board -> Schiit Asgard 3 amp
- Questyle M15 DAC/AMP dongle
- Sony Walkman NW A-55 DAP (Walkman One WM1Z Plus v2 Mod)
- Sony Walkman NW A-55 DAP (Walkman One Neutral Mod)
- Sony Walkman NW WM1A DAP (Walkman One WM1Z Plus v2 Mod)
- Smartphone

This flathead is moderately difficult to drive due to the 45 ohm impedance. While it can be driven off a weak smartphone, the FF3S definitely scales better with amplification, in terms of dynamics and bass texturing.


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The following impressions are done with full foams installed.

The FF3S can be described tonally as having a bassy L-shaped profile. It is a warm and smooth earbud, suited for longer listening sessions, unlike thinner and more fatiguing counterparts.

The bass is north of neutral, with a huge thump which is focused at the mid-bass. The bass quantity is quite exceptional for a earbud, with decent sub-bass extension compared to other traditional flatheads, due to the aforementioned flute acoustic tube design. Despite the copious bass on tap, the quality is not too compromised, and we hear a textured and fast bass, with just slight mid-bass bleed (this is way less than expected for such a bassy bud). I didn't note much smearing even on complex bass tracks.

The lower midrange is a tinge depressed, but not overly so. This area is warmed by the slight mid-bass leak, giving a lot of heft and thickness. The upper mids are slightly forwards without being shouty (at moderate volumes), which is quite appreciated.

The FF3S is smooth in the treble, and may not be the cup of tea for trebleheads. Surprisingly, clarity is still very decent, and we do not lose too much micro-details for a darkish signature. Treble-sensitive folk will surely like the tuning on offer, with minimal sibilance and splashiness heard.

Timbre is very natural, in keeping with the usage of a dynamic driver, with no artificial or metallic overtones heard. Note weight lies on the thicker side, as discussed.

In technicalities, the FF3S does above average for a sub $100 set. Soundstage is expansive in all 3 dimensions, though imaging is a hair fuzzy, so placement of instruments may not be pinpoint. Instrument separation is solid, and despite the darker tuning, micro-details are quite preserved.


Comparisons were made with other earbuds residing just below the $100 USD bracket. All A/B comparisons were done with full foams installed, to compare like-for-like as differing foam covers can change the sonics.

FF3 12.jpeg

Fiio FF3

The predecessor FF3 is heavier in weight due to its steel exterior (it weights double of the FF3S). Thus, the former's build seems more robust but it can cause fatigue in the ears with longer sessions, compared to the successor FF3S.

With the different shell materials, there are some slight sonic differences. Both generally share the same DNA in being bassy and warm sets, but the original FF3 is even bassier but less resolving, losing in technicalities and treble extension. For folks who found the first FF3's bass to be intrusive, the FF3S tones it down slightly here, thus allowing the rest of the frequencies to breathe more. I'm not a bona fide basshead, so I do prefer the FF3S's more versatile sound signature in a way.

The original FF3 has a non-detachable cable, though it also has modular plugs (albeit one can argue that having a proprietary detachable cable in the FF3S isn't a true improvement in this department).

DUNU Alpha 3

The Alpha 3 is a non-detachable earbud with only 3.5 mm termination. It is a brighter bud with less bass but more fatigue/sibilance in the upper registers.

Timbrically, the Alpha 3 is thinner in note weight. The Alpha 3 also has a smaller soundstage and poorer instrument separation. It has a hair better imaging and micro-details.

Smabat ST10

The original ST10 is a more aggressive V-shaped tuned earbud. Sub-bass is more profound on the ST10 due to a conch acoustic labyrinth tube, though the upper mids and treble are more fatiguing and sibilant.

The ST10 is more metallic in timbre, sounding notably artificial in this area.

Technically, the ST10 has a smaller soundstage and worse instrument separation, but superior imaging and micro-detailing. The ST10 is much harder to drive. It has a standard MMCX detachable housing, unlike the proprietary 2-pin one in the FF3S.


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The FF3S is a great addition to the MidFI earbud stable, bringing a smooth and sedate soundscape to the table. Build and ergonomics are solid, and the accessories are second-to-none. Timbre is a delight, and the FF3S boasts of big bass that still retains a high level of quality, due to a flute-acoustic tube design.

Treble-sensitive peeps will be at home with the tuning, though trebleheads might be alienated due to the calm and tranquil treble. I'm also glad to report that the FF3S's soundstage is also bigger than some competitors at this price range.

Though weaker sources can be paired with it, the FF3S does take a bit of juice for optimal sonics. The proprietary cable is a disappointment too, though haptically it is very well designed (zero microphonics with modular distal plugs).

Of note, the FF3S improves on the predecessor FF3 by bestowing better resolution and a less bombastic bass (which some may find intrusive). Also, the shells are lighter and cause less discomfort as such. The FF3S has my recommendation for earbud aficionados looking for a serene companion for long listening sessions, yet retailing decent technicalities.
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Excellent review
Great review brother. Glad you took one for the team on these. Would you say that they are different enough from the OG FF3 to have both sets?
Thanks @samandhi , probably not great value-add to get the FF3S if you already are an FF3 owner, as both are bassy and warm pairs, the FF3 of course being bassier but less clean

Not sure if the funds are better funneled to a earbud with greater tonal change (eg something brighter for example?). You in all honesty probably own something higher end like the Yinmans.


100+ Head-Fier
Neutrality Buds
Pros: +Timbre
+Neutral Sounding
+Build Quality
+Modular Cable
Cons: -Stiff Cable
1DD Earbuds

First, I want to thank FiiO for sending the FF3S for review, this review is 100% my own personal opinion and FiiO did not have any input at all or even a chance to read this before I release it to you guys.

You can check the FF3S here

What you get inside the box :
  • Earbuds
  • Cable
  • Multiple Silicone Ring and Foamies
  • 4.4mm Modular Plug
  • Case for storage
  • Manual
Build Quality
The shell is made from an aluminum metal type. It is very light weight but feels sturdy at the same time.
The cable is a bit stiff, but it is detachable with modular plug, there is a 4.4mm and 3.5mm plug included in the package.

is just like your typical earbuds, nothing to comment here.

Tested using : Hiby FC6, Cayin RU7, Stock Cable, All Stock Foamies and Silicone
Music mostly from Apple Music (J-POP, J-Rock, EDM, Rap, Jazz, Metal)

Tonality in General : Neutral

here is pretty deep and extended for an earbuds, probably thanks to back drum design of the FF3S.
You can hear some sub-bass though mostly is rolled off due to the design, and bass here is more focused on the mid-bass region rather than sub-bass, bass quantity is mostly neutral / flat and will not satisfy a basshead for sure.

The presentation of bass here is pretty good, especially using the bass foam, it has a very good mid-bass slam and impact, with decent rumble with a normal transient and speed / decay.

I tested the bass speed with track Catasthropist by Trivium and it can keep up pretty well with the double pedal speed, so no problem there.

Midrange is lush and rather forward, without never sounding nassaly, shouty and sibilant. Midrange here is definitely the main focus of the FF3S sound.
It has a very good note weight, both male and female vocals are rendered with good and full bodied sound.

Instruments such as trumpet, saxophone, violin, etc are also rendered very realistically, the timbre here is top notch in my opinion, no complaints from me at all, very good.

With different foam it can affect how the midrange sounds. With the Bass Foam, the mids is leaning towards warmer side, while the Donut Ring Foamies make the mids has more clarity and air.

My preferences is with the Bass Foamies, because it sounds more lush to my ears.

Treble on the FF3S is a bit rolled off like the sub-bass, probably due to the open design.

The presentation is also affected with what foam you're using, if you use the Bass Foamies, treble is more smoothed out but still somewhat airy, while with the Donut Foamies, treble is more forward, making overall presentation has more air and clarity but never piercing

Overall with the FF3S I prefer using the Bass Foamies. Why so? Well because it made the sound leaning towards Warm – Neutral, Lush, Smooth and comfortable for long listening session, but hey, you can experiments with different foam to suit your taste more.


is pretty wide and open, thanks to the open design, it has nonsymmetrical shape, there are more width vs depth, so the stage here is sounding somewhat oval if that makes sense to you.

Imaging is decent, I'd like to describe this kind of sound presentation as 2.5D sounding, it has very good object rendering but lacking the holographical pop up effect

Separation is decent, not the most separated sounding presentation but has decent separation to not sound claustrophobic and congested.

Positioning is also decent you can pinpoint the source of the sound coming from, and I also have tested this with Valorant and I can hear the foot steps no problem at all.

I won't do any comparation because I lack resources of earbuds with this kind of price tag.


Is the FF3S worth it?
Well it is up to you to decide, myself as a reviewer only helping you guys to have more data on the Internet as a reference.

For me personally, I rarely wear an earbuds, but one thing I can say that this one sounds very good, It is somewhat reminds me the sound of HD580 and HD660s with less technicalities of course.

So I guess if you're looking for an earbuds that has neutral sound with budget less than $100 USD, you can consider the FF3S or at least add it to your list.

Thanks for reading this far !

Just in case you're Indonesian or understand Bahasa Indonesia, you can watch the review of this earbuds here

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