Review: FiiO FD5 – Superior Soundstage Soundshifter

The FD5 are intriguing from every angle.
The FD5 are intriguing from every angle.

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Headphones masquerading as earphones.

First, a sincere thank you to Linsoul for allowing Headphonesty to review the FiiO FD5. As is my standard, I did not read any reviews of the FD5 before my evaluation.

FiiO has done a remarkable job since their launch in 2007, building their hard-earned reputation through innovative in-house R&D, quality products, and extensive industry accolades – not celebrity endorsements and marketing hype. FiiO has a raving, loyal fan base around the world because they have consistently delivered excellent products with exceptional innovation, performance, quality, and value.

The FD5 are FiiO’s newest dynamic IEM flagship. After adding them to your collection, these may be your last. I know that seems like an outlandish and presumptuous statement, especially shocking as these are single dynamic driver earphones. FiiO designed these for flexibility of personalized sound tailoring. They almost guarantee that you will find one or several combinations that suit you, your moods, and your choices of sound and music.

Bottom Line

With this addition, FiiO has brought forward a very strong contender in this price category. Many others are much more focused and picky, while the FD5 is an all-star. If these are in your affordability range, I suggest that you experience these for yourself and compare - your quest for excellence in IEM sound may come to an end.

What We Like 😍
  • Impressive and attractive form and function
  • Engineering and innovation is forefront
  • Extensive set of accessories and hardware-based sound customization options
  • High quality fit and finish
  • Exceptional tuning with little evidence of harshness
  • Cohesion of perceived sound
  • Smooth treble
  • Powerful and tight bass with good texture
  • Sound optimized to the Harman Curve without external EQ
  • Soundstage and imaging is superb
  • Optional true wireless Bluetooth Amplifier ear hooks for even greater flexibility of use
What We Don't Like 🤢
  • Tone may be too warm for some who prefer neutral, flat “audiophile reference” sound signatures
  • No customized fit
  • No microphone option

What I first wrote in my most recent review is worth repeating once more. Based on your feedback, dear readers, I will consistently make my reviews a journey in sound and showcase for diverse global music. I hope that you take the time to listen to the artists and expand your musical horizons.

The links posted will generally be YouTube or YouTubeMusic links. Please note that the quality of these online files vary drastically and are provided for quick reference. I primarily listen and evaluate from original source CDs or high-quality lossless files when available. You can likely source them through high-quality streaming services. Let me know if you find some new favorites, and please share yours with us at Headphonesty! 

First Impressions

The FD5 IEMs are much more attractive in person, especially when revealed in the light upon opening the deep black box. I believe I heard them beckon me to set them free from their secure throne in which they have been securely resting. Me with a bowed head and still maintaining eye contact: “Yes your majesty, right away my Lord.”

Carefully extracting them reveals their substantial weight and depth. I am wondering how what appears to be such a simple, somewhat large stainless steel circular body will fit ergonomically in my ears… and if the weight will be a fatiguing factor for comfort.

After a lengthy burn-in period (72-100 hours), I always begin evaluations with the same protocol: experiment with all of the ear tips to find the best fit. In addition, I do not use secondary EQ adjustments while testing.

I am impressed by the large and varied collection of ear tips and the thorough collection of accessories. The most curious are an extra pair of interchangeable nozzles (sound tubes). Also present are interchangeable audio plugs, a tool to safely detach the cable connectors, and a small cleaning brush. I can feel my anticipation building, this is going to require some fantastic experimentation!

A major FiiO innovation: interchangeable nozzles (sound tubes)!
A major FiiO innovation: interchangeable nozzles (sound tubes)!

Before we proceed, let’s pause for a moment. Interchangeable sound tubes?! FiiO had innovated interchangeable hardware-based filters in the past, as seen on the flagship hybrid Fiio FH7. Click here if you’d like to read an equally innovative review that my colleague Lau wrote in 2019. For the FD5, FiiO changed from swapping filters attached to the tubes to swapping the entire sound tube.

As with all IEMs, the right ear tips and seal are crucial to realize the best sound and isolation. It is always worth the time to experiment until you find what’s best for you. Please reference this Ultimate Guide to Selecting the Perfect IEM Ear Tips.

Despite an attractive face, some audiophiles and enthusiasts will be skeptical of the FD5. The Western mentality of “more is better” is still raging. There appears to be an IEM audio arms race with the number of drivers that can be crammed into a stylish, highly-contoured molded resin body meant to nestle into a wearer’s ears. Many believe that more drivers will result in better sound reproduction and that lightweight ‘custom-type’ shells are more premium and comfortable.

The doubters voice these questions: “How can a single driver be good enough? How can a simple outer body design be comfortable?” In addition to these questions, prices and performance range wildly in today’s market: from ultra-affordable to unaffordably expensive, and from utilitarian to highly specialized.

Higher consumer cost does not consistently equal quality or performance.

Back to the present in our current scenario, the FD5 metaphorically arrive at the party. After boldly kicking the door open, they warmly smile, smoothly enter the room, and grace all with their presence — no apologies. The FD5 immediately begin a captivating modern ballet performance. I can only feel honored that I am witness to something special.

Company Overview

FiiO (pronounced “Fee-Oh”) was established in 2007 (formally Guangzhou FiiO Electronics Technology Co., Ltd.). The brand name FiiO is composed of Fi (fidelity from HiFi) and iO (number 1&0), representing the real feeling and convenient life that digital brings to life. The Chinese “飞傲” is the transliteration of FiiO, indicating the positive and innovative spirit as thriving as spring.

FiiO is focused on innovation, quality, and service. They have extensive experience in research, development, and design of countless portable music products, including high-resolution digital audio players, portable headphone amplifiers, DAC/Amps, and earphones.

Over the years, FiiO has earned a strong reputation and immense consumer popularity as a top Chinese manufacturer whose products have received countless international awards, including iF Design Award, Reddot Award, EISA Award, VGP Award, etc.

Technical Specifications

  • Transducer driver: 12mm beryllium-coated diamond-like carbon (DLC) dynamic driver; utilizes N52 magnets with a high magnetic flux of 1.5 Tesla for robust bass and excellent high frequency resolution
  • Impedance: 32Ohms
  • Sensitivity: 109db/mW
  • Frequency range: 10Hz – 40kHz
  • Maximum input power: 100mW
  • Noise isolation: Passive
  • Style: In-ear, with earhook cable
  • Connector: Standard MMCX
  • Plug type: 2.5mm / 3.5mm / 4.4mm gold-plated straight plug
  • IEM weight: 11 grams each (excluding ear tips and cable)
  • Cable length and type: 1.2m (3.9 ft) detachable 8-strand monocrystalline silver-plated copper
The FD5's MMCX connectors are a secure fit.
The FD5’s MMCX connectors are a secure fit.


Packaging is substantial, stately, and suiting of a TOTL (top-of-the-line) premium product. The outer printed coated cardboard wrap slides off to reveal an attractive black box embossed with a silver line art rendering of the FD5. Upon opening the magnetically secured cover lid, I discover an upper foam tray displaying the IEMs to maximize the striking visual beauty of the faceplates and the cord, as well as present the luxurious looking and feeling blue and brown storage case.

The initial presentation of the FD5 and their premium travel case.
The initial presentation of the FD5 and their premium travel case.

Grasping the silken tabs on the sides of the upper tray, I remove it to find another tray underneath, holding securely a thinner black box of accessories and a well-organized large selection of ear tips seated in a compact foam brick with their designations pressed physically into the foam for easy identification. Just lovely!

The carrying case it itself a work of art to be appreciated.
The carrying case it itself a work of art to be appreciated.

In the box

  • FiiO FD5 IEMs
  • 1 detachable high-purity Litz monocrystalline silver-plated copper cable (1.25m long) with 2.5/3.5/4.4mm interchangeable plugs, no microphone available
  • 5 sets of ear tips (3 “balanced” pairs, 3 “bass” pairs, 3 “vocal” pairs, 2 memory foam pairs, 2 tri-flange pairs)
    • Red and black ear tips (S, M, L): “bass” ear tips
    • Translucent white ear tips (S, M, L): “balanced” ear tips
    • Red and white ear tips (S, M, L): “vocal” ear tips
    • Tri-flange ear tips (S, L): designed for the small sound tube only
    • Memory foam ear tips (M): adaptable fit for ear canals with improved noise isolation
  • A beautiful and sturdy blue and brown travel case (Model HB5) with magnetic closure
  • 1 cleaning brush
  • A yellow plastic clip-type tool to detach the MMCX connector easily
  • 2 sets of interchangeable sound tubes (nozzles)
    • Large sound tube (preinstalled on FD5): the outer diameter is 5.8mm, for use with 4-5mm ear tips
    • Small sound tube (included in accessories): the outer diameter is 4.0mm, for use with 2.0-3.5mm ear tips, specifically the included tri-flange tips
  • Printed Quick Start booklet that provides basic information and a how-to guide for swapping audio jacks (much more specific detail and instructions can be found on the official website)
The FD5 comes bundled with extensive and unique accessories.
The FD5 comes bundled with extensive and unique accessories.


The 8-strand high-purity Litz monocrystalline silver-plated copper cable appears and feels premium in every way, perfectly matching the chrome brilliance of the IEM bodies. The cable consists of 152 total wires (each individually insulated!), bundled into 8 strands, 19 wires/strand. A single wire diameter is .08mm, each strand 24AWG, and the entire cable 18AWG.

The braiding of the silver cable is flawless and flexible. The chrome-colored plastic protective splitter is sturdy and has a smooth sliding cinch that travels easily up from the splitter. All terminal connections are secure, the MMCX connectors for the IEMs and the audio jack at the other end.

The included silver cable, 3.5mm plug (1 of 3 interchangeable plugs) and MMCX connection.
The included silver cable, 3.5mm plug (1 of 3 interchangeable plugs) and MMCX connection.

The twist-lock swappable audio jack allows you to switch between included 2.5mm / 3.5mm / 4.4mm plugs to fit your devices. The cable employs a straight plug design that I am so thankful was long enough to make a solid click connection into all of my phones/DAPs despite wearing cases (this is an absolute rarity and often a great source of frustration for me with other cables/plugs).

The cable transmits no microphonics. The ear hooks have a subtle and thin clear plastic sleeve to help retain shape and for a flexible fit around the ear. They are secure and comfortable enough to be unnoticeable.

Another innovation of significance is an accessory that may be super exciting and useful for many buyers (me included). FiiO previously created a true wireless Bluetooth Amplifier that replaces the cable and attaches to the MMCX connectors of corresponding IEMs. The new generation of these are called the UTWS3, due to be released soon.

FiiO's new true wireless Bluetooth amplifier MMCX accessory, the UTWS3. (Source:
FiiO’s new true wireless Bluetooth amplifier MMCX accessory, the UTWS3. (Source:


The physical appearance of the FD5 are structural attributes designed to improve sound performance.

“Art and Science in harmony – the stunning curved cylindrical design of the FD5 is actually a benefit for acoustics, as such a design greatly reduces unwanted resonances and reflection of sound waves within the body – allowing every last detail of your music to be faithfully reproduced.” – FiiO

According to FiiO, the third generation design is based on carefully designed curves, evoking majestic mountains and wondrous waterfalls. These curves combined with a faceplate offering two distinctly different textures form a sort of “acoustic art” that needs to be experienced in person.

The smooth, luxurious-feeling 3D embossed stainless steel faceplate represents both form and function – while looking striking, the robust stainless steel also reduces the harmonic distortion of sound inside the FD5. The faceplate provides a striking contrast against the polished chrome finish of the rest of the FD5 as well.

Each FD5 IEM outside housing is assembled in three pieces: nozzle (interchangeable sound tube), body, and faceplate — all stainless steel. The nozzles can be changed by hand and thread perfectly. Ear tips are highly secure once properly fitted.

The FD5 has multiple structural features to relieve inner-ear pressure, including the net holes through the faceplate.
The FD5 has multiple structural features to relieve inner-ear pressure, including the net holes through the faceplate.

The FD5 are a semi-open acoustic design. Closely inspecting the faceplate, you will notice small holes (called net holes) between the curved rising vertical ridgelines. Through these and a hole in the other side of the body, air pressure on the ear is relieved and moderated – leading to more natural, comfortable, and long listening sessions.


Despite my reservation about weight, size, and shape, FiiO has once again been a step ahead and clearly did their homework (R&D and testing). The IEMs are secure in my ears with the proper ear tips and do not require frequent adjusting. The weight almost disappears due to the cable shape and suspension. For me, the FD5 are so well balanced that I do not notice them and remain comfortable for long listening sessions.

The FD5's nozzle, body, and cable make for a comfortable combination.
The FD5’s nozzle, body, and cable make for a comfortable combination.

The body to nozzle angle results in no uncomfortable contact to the ear while still achieving excellent sound isolation using standard ear tips. While everyone’s ears are different, I find that the FD5 are all-day comfortable with an average nozzle length and moderate depth of insertion into the ear canal with all ear tips (except the tri-flange). The tri-flange, as always, may insert too deeply into the ear canal to be comfortable for some people.

After spending much quality time with the FD5, I do believe that the semi-open design and vent holes are especially effective. Absent is any vacuum-like pressure when wearing or removing the FD5 despite what I feel is a particularly tight seal. Another phenomenon I am glad is missing is any sense of disorientation after extended wear from said pressure.


The dynamic drivers of the FD5 employ beryllium-coated surround plus diamond-like carbon (DLC) diaphragms, elements of audiophile dreams. Drivers, no matter how formidable they are alone, produce sound that differs greatly depending on a complex set of variables. FiiO has innovated and applied multiple acoustic technologies, including:

  1. Front acoustic prism
    • A conical device designed and installed close to the front end of the driver diaphragm precisely controls how the sound waves travel in the sound tube – bringing benefits such as eliminating high frequency standing waves and enhancing overall sound wave diffusion.
  2. Rear volcanic field system
    • The volcanic field system is an anti-standing wave structure we designed for the rear cavity of the FD5. By reversely preventing harmful standing waves, it plays an important role in enhancing bass diffusion at the rear cavity, reducing standing waves and distortion, thus achieving clearer sound.
The FD5 features many FiiO innovations.
The FD5 features many FiiO innovations.

FiiO FD5 Sound

Powerful, yet silky and smooth. Deep-voiced, yet clear and crisp. Full-bodied and bold, yet delicate. These polarities generally do not harmoniously co-exist. When they do, music can shift from engaging to enveloping – and transform the listening experience into an all-encompassing experience. That’s how good the FD5 are.

The coherence and spaciousness that FiiO has achieved is often stunning and leaves me shaking my head, unsure if I am to believe what I’m hearing. I have multiple times now needed to verify with my hands that I am not listening to headphones. FiiO has created a width and vastness in the soundstage in a natural way that I’ve not experienced before in IEMs without extensive digital signal processing and/or sound modulation.

Before I go further, a note about sound customization options. The FD5 come with interchangeable sound tubes. According to FiiO, the large sound tube is “balanced” and the small sound tube presents a lively, more bass-focused sound (note that only the tri-flange ear tips fit the small tubes).

The FD5's smooth metal body and wider bore balanced nozzle.
The FD5’s smooth metal body and wider bore “balanced” nozzle.

While I have every reason to believe FiiO, I cannot validate the small tube with tri-flange difference. As excited as I am about the interchangeable sound tubes, I am almost equally disappointed to admit defeat in trying to make the included tri-flange tips seal well for me. I have another set ordered which have not yet arrived as of the publishing of this review.

Given how strong the bass is on the “balanced” tube paired with the “balanced” or “bass” ear tips, it’s hard to imagine needing or wanting any more. The varied tips make enough difference that you will also likely find a personal preference in fit, comfort, and sound.

The FD5 tuning is mindful of the Harman Target Curve (a research-based sound profile that is suited to most people’s preferences). They are not reference-type flat in tuning or sound reproduction. Compared with a multiple-driver IEM, there is only one point from which the sound is produced from a single driver in the FD5, resulting in more accurate sound positioning and clear imaging.

The FD5 is tuned closely to the Harman Target Curve. (Source:
The FD5 is tuned closely to the Harman Target Curve. (Source:

I find that throughout the frequency spectrum, transitions sound seamless, simultaneously well-integrated and distinct. The FD5 generally tends toward a warmer sound profile with a relaxed, natural sound.

The FD5 are Hi-Res (High-Resolution) Audio certified, as are the majority of FiiO products. They excel with every type of music and sound I challenge them with, including action movies, deep house, drum ‘n bass, and EDM. I did not notice distortion at any volume.

For evaluation, I listen to a great variety of music through numerous sources, including:

With a high sensitivity of 109db and a relatively low impedance of 32 ohms, these IEMs are easy to drive with virtually any source. The use of a quality DAC/Amp can only help drive the FD5 more effectively. Passive sound isolation is well above average with proper-fitting ear tips. Channel separation is excellent and the soundstage is huge, complemented by impressive imaging, spaciousness, and wide dynamics.

When headphones, earphones, and IEMs are designed and tuned, there are usually trade-offs in sound reproduction and the listening experience. As a result, many develop a reputation for their unique “sound signature.” The FD5 exhibit gymnast-like flexibility between styles and genres of music.

These are ideal IEMs for deep listeners who truly want to be absorbed into their world of music. For this review, we will take a musical journey primarily through northern Europe for a wide range of music to highlight all of the FD5’s abilities, with one side trip below the equator to Africa.

The FD5 create full and engaging sound across all frequencies.
The FD5 create full and engaging sound across all frequencies.

Gift yourself the time to journey into other worlds through this live performance by Heilung, an experimental folk music band made up of members from Denmark, Norway, and Germany. After experiencing this intense performance, you must read the comments – you’ll thank me later after you recover.

For a much cleaner and higher quality recording, listen to their official video for Heilung Norupo. The layering of sound in both pieces are complex – listen for the depth, imaging, texture, and sense of realism.


Overall, bass is plentiful enough to satisfy bass-lovers and not so much that it will turn anyone else off. It is generally natural and appropriate to the source.

The FD5’s bass is clean-cut, well-dressed, and authoritative. At the same time, its presence is comforting and is the last one to leave and shut off the lights. The way the bass fills out the sound profile without overwhelming the spectrum of sound and detail is remarkable.

Sub-bass rumbles without literally vibrating your ears or head in an annoying way. Mid-bass impact has speed and strength, with slightly long decay to make music full and juicy (not clinical sounding).

The FD5 produce strong, full bass due to the powerful magnets and unique structural innovations.
The FD5 produce strong, full bass due to the powerful magnets and unique structural innovations.

Listen to Val Jeanty AKA Val-Inc’s “Kwa” Feat. Buyu Ambroise. While this Afro-electronica experiment in sound ranges across all frequencies, it’s an excellent piece of music to hear and distinguish different types of bass presentation. The FD5 delivers punchy and clean bass with broad dynamics.

The FD5’s driver is not the fastest resolving, which you may love. What this means is that the bass both sounds and feels full. This gives music a sense of body and volume (reminiscent of classic shampoo commercials).

Pairing the FD5 with its cousin, the FiiO A3 amplifier, the bass boost option is unnecessary and does not improve the sound profile or reproduction.


The midrange is rich and full; most often silky, distinct, and well placed. When this is the dominant range of the music you are listening to, it’s all there. When placed in the full mix, it does not stand to the front and center, as is quite common in IEMs.

With music in which high dynamics are emphasized, it seems at times as if the midrange is ever so slightly pulled back in the mix. This is not to say that there is deterioration or loss of articulation, it’s simply a matter of the bass and treble being forward by a small margin in what will grab your attention.

Now let’s travel to the Netherlands by way of Basel, Switzerland. In Candy Dulfer’s Lily Was Here, the saxophone and guitar express midrange and treble mixes and transitions beautifully. The sound of a saxophone ought to be smooth and natural; the guitar in this piece, clear and lively.

FD5's midrange is smooth, well-integrated, and not overly forward in the mix.
FD5’s midrange is smooth, well-integrated, and not overly forward in the mix.


Treble is smooth and balanced enough that I have yet to experience any unpleasant sharpness or fatigue. Clarity and detail are definitely good and enough to hold their own with the prominent bass and lower midrange.

Next stop, Norway: Aurora’s cover of Massive Attack’s Teardrop is a perfect example of deep bass and treble co-existing in a phenomenal mix, in my opinion, better than the original. This rendition brings chills. Bass attack, decay, and texture are outstanding with high treble clarity and extension that does not become shrill. Sibilance and harshness are missing and yet to be found.

Other IEMs may provide more ‘sparkle,’ airiness, and openness in the high end. This is more typical of earphones with balanced armature drivers dedicated to higher frequencies. For me, I do not need any more treble to feel completely satisfied with the amount of lively detail and space in the FD5’s reproduction of higher frequencies.

Where to Buy

Thank you once again to Linsoul for providing the FiiO FD5 for review. If you’d like to purchase a pair, you can buy them directly from Linsoul or Amazon.


Yes, they have earned their flagship title through performance and enjoyment, not innovation and technical achievement alone. While many audio enthusiasts are collectors whose hobby thrives on obsessively buying and trying more and different (that’s what we enjoy!), the bulk of the buying market truly appreciates high quality, dependability, and not wanting for more.

Are the FD5 worth the price? I believe they most certainly are, and they will likely be an investment that you won’t regret and a product you will not grow tired of. If, for some reason, you decide you want something different, alternate the included tubes and tips. It will be almost like having another IEM without buying more products in search of something greater.

The TOTL designation and price tag are appropriately matched to the innovation and performance of the FD5.
The TOTL designation and price tag are appropriately matched to the innovation and performance of the FD5.

With this addition, FiiO has brought forward a very strong contender in this price category. Many others are much more focused and picky, while the FD5 is an all-star. If these are in your affordability range, I suggest that you experience these for yourself and compare – your quest for excellence in IEM sound may come to an end.

FiiO innovates and impresses based on true in-house R&D, technical expertise, enthusiast passion, and fashion sense – without being swayed by the ‘most popular’ moods and attitudes, which change with the winds. As they continue to produce some of the best products in their classes on the market, FiiO will also continue to be the trendsetter, not the trend follower.

💬 Conversation: 5 comments

  1. Another great review, Eric. This is the first IEM I’ve seen with interchangeable sound tubes. I hope that trend catches on.

    1. Oren, thanks so much for your support. About the tubes, yes – we will see!

    1. Johnny, I’m sorry I did not reply sooner, I missed your question and see that no one else has jumped in. This may help:

      This is also a great question for our Headphone Audio Facebook Group community. The B2Dusk (5-driver hybrid – 4BA and 1DD) is one that I’d very much like to hear, and have not yet had an opportunity! Please share with us if you have a chance to hear them both, or have gotten one and have impressions. Happy Listening!

  2. FD5 is an Inears with placebo effect, yes, placebo. Will you be wondering what I mean? It comes to you with a more or less pro box, with a nice case, tool, a braided cable, and some iem that seem more designed by a master jeweler than by an engineer.

    So you open the box and wow! For 200 dollars it’s not bad at all.

    But you start riding and it turns out that putting on and removing the rubber bands is almost an exercise of not breaking them. You put your device in your pocket and you feel like that braided cable is going to break soon so close to the miniplug. The case there is no way to install the headphones without folding them all, it is more beautiful but zero professional and with a design made by the seller’s grandmother, nothing practical.

    And now comes the worst, the sound.

    Since you think you are before the design and the brand of the moment, you think that what you are listening to has quality, because it has very clear mids and highs. But it turns out that you put on some KZ of 20 usd and they almost sound the same. You think the sound is good because you want to believe it, but it’s not like that. You hear a ghost of the reality, certain frequencies that cover the rest so the track reduces it to 40% of reality. But you don’t know, because you’re still in the placebo effect.

    To this we must add that FIIO’s customer service is non-existent, they can’t do anything to help you if there is a problem, such as that mine had noises and was defective and they never accepted it and now they are in the trash box, 200 usd in recycling. It is a superb Chinese company, which has complaints everywhere for cloning technology and patents. Never FIIO again, never again!

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