Itsfit Fusion

General Information

As the world’s first tri-brid earphone with Magnetostatic™, the Itsfit Fusion is the result of our quest for a true innovative in-ear technonogy that conquer even the most demanding records. One of its most remarkable trait is the incredibly wide soundstage that promise to recreate the truest performing space feel.

Expertly tuned with the goal to create the most musical yet of highest fidelity sounding earphones, Fusion always leaves you wanting more.

This model is available in both Universal and Custom version.


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Pros: Very good design and great shell customization
Top-notch detail retrieval & imaging
Excellent bass, very wide & deep sound stage
Natural & clean mids
Energetic, sparkly treble
Open and airy sound
Cons: None.
Itsfit labs Fusion Review


ITSFIT LAB is a custom in-ear brand (CIEMs) that was originally a small lab specialized in sound & audio components research in Vietnam. They have been in re-shelling business since last 3 years and have ventured into IEM market with their first ever set of IEMs, R3 at 305$ and the flagship, Fusion at 950$. They can be ordered in both universal and custom designs. This review is about their flagship, Fusion, which is a tri-brid IEM, and is among the very first to use a magnetostatic driver. Specifications, as sourced from their website:

Configuration: 1 Magnetostatic driver for highs, 2 BAs for high-mids & mids, and 1 Electro-dynamic for lows. Frequency Response: 4Hz – 40kHz. Sensitivity: 98 dB/mW @ 1kHz. Impedance: 13.1Ω @ 1kHz. Isolation: -26dB.

Design, Build & Fit:

Fusion comes in a nice rectangular black box, which holds the IEM along with its cable, 3 pairs of ear tips, and a round metal box. Itsfit labs, even provide inscription on its lid mentioning their brand name and the buyer’s name, which is quite nice. Even nicer thing is that you can request them to write whatever you like on the lid. The stock cable, seems to be a SPC cable, encased in black plastic, feels light and nice to hold and has good build. Connectors and plug are nicely built and look classy. Connectors do have markings to differentiate right and left. IEM’s build and finish are excellent, and it has really very good shell designs to choose from. Fit and finish are excellent, has minimal protrusion. Comfortability is excellent too and can be used for long hours, being very light and made of acrylic shell. Isolation is okay in these because of the three bass vents it has on its shell, and I needed to ramp up the volume in noisy places to weed out external noises.

Sound Quality

I had used Cayin N6ii DAP with A01 module and 3.5mm Electro Accousti 7N Neotech UP-OCC Copper Cryo Litz cable on Fusion for the purpose of this review. I didn’t use Fusion in balanced, as I feel N6ii’s SE sounds more open than its balanced end.

Bass extends deep, is rich, tight, clean with superb control and has very good sub-bass rumble, not like a subwoofer but very enjoyable, foot tapping rumble. Bass impact is quite fast and has short decay.

Mids sound very natural, clear with a slight tinge of warmness and has tons of details. Mids are placed in center of the stage and very slightly recessed. Male vocals sound natural. Female vocals sound natural and more energetic.

Detail retrieval and resolution are top notch. You can hear each instrument used precisely and with utmost clarity. Instrument separation is excellent too with very good space between different instruments. Cymbals sound crisp and natural. Timbre is very natural and clear.

Sound stage is extremely wide and deep, three-dimensional, holographic stage with very precise imaging. Sound envelops you in a 3-d way and you can easily pinpoint the exact position of the instrument being played. This is easily one of the best traits of Fusion. The enormous sound stage wows you the moment you try it.

Treble is the best part here. Itsfit has utilized magnetostatic driver in the best possible way and the resultant treble has got excellent extension and sounds very open and airy. Treble is energetic, sparkly and very detailed and is not fatiguing or sibilant.


Fusion, with its excellent sonic performance throughout the spectrum, provides itsfit labs a great platform to succeed in TOTL IEM market. With its top-notch performance, Fusion is an easy recommendation. I didn’t hear many other IEMs that fall under its price range, but with its excellent bass, very good mids, extraordinary sound stage and treble, it can stand on its own and compete very well against its competitors.


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Holsen, yes, it's quite a stunt to insert third party cables but they can be inserted easily after 2 or 3 tries. Fusion has a recessed 2-pin slot and its 2-pin connectors even more. So it's not that easy to connect other cables.
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What tips were you using? I just switched to wide bore Whirlwinds and they took whar was very good and turned these Fusions into spectacular. Whatever tip is in your Pic, it seems to have a similar width.
The wide bore tips that came in the box. Fusion will be at its best with wide bore tips. And a friend of mine suggested Final Type E Tips too. You can try that.
Pros: hyper-real vivid presentation, energetic, dynamic, detail, world class imaging
Cons: may be too energetic for some with sensitivities; cable & tip choice can help
Nuclear Physics:

A review of the Itsfit Fusion IEM.


I would like to begin by thanking Kien at Itsfit for providing me with a Fusion IEM at a discount in exchange for my honest review :)

IEM details may be found on the Itsfit website:

Itsfit is a small company in Vietnam, that evolved out of a small lab specialised in audio and audio component research.

Their latest and top of their range IEM, the Fusion, is one of the new breed of ‘Tri-brid’IEM’s, which usually feature a combination of a dynamic driver, one or more balanced armature drivers and one or more electrostatic drivers, or occasionally a planar magnetic driver instead.

The Fusion follows this pattern with 1 dynamic driver for the lows and 2 BA’s for the mids and high-mids.

However, Kien at Itsfit has kicked the innovation machine into overdrive by introducing a possibly world-first magnetostatic driver in an IEM to manage the highs on this flagship product.

For those fascinated with Fusion physics (ho ho), here’s a bit more detail:

Adapted from their website: “Our Magnetostatic™ driver is a Hi-res certified driver that uses two pairs of permanent magnets symmetrically and independently moving a membrane in between.

This ultra-thin 5-layer ferromagnetic membrane with high magnetic permeability moves its entire surface without any dead points, minimising sound loss, transfer delay and distortion. There’s also no need to use high-voltage amping like Electrostatic drivers commonly employ, making your listening journey much smoother”.

Pricing at the time of writing was USD $950 which I would say places it somewhere around the beginning of TOTL range in terms of pricing.

It is available in both universal and custom options, with the universals available in (if I recall correctly) 3 different shell options.

I chose a universal, but Kien very kindly agreed to custom-make the universal shell in his ‘Koi Lake’ design, one of the many beautiful designs he has created for the custom products.







Appearance and build:

The product came in attractive and understated black packaging, with the kind of hefty metal carrying case that’s becoming quite standard in higher-end IEMs these days. The classiness of the case is undermined somewhat by the slightly grammatically incorrect (and somewhat cheesy) inscription upon it. I’m not judging Kien’s English in any way, since my Vietnamese is currently limited to a few words :)

However, by way of feedback to him and those considering to buy an IEM from him, I’d suggest that any potential customers be very clear about what they want written on the case, and also on the IEMs themselves, should you be ordering a custom design (and of course that Kien sticks exactly to what they say).

I just said “I don’t want my name on the carrying case” and left it at that, so I can’t really blame Kien for wanting to let his natural exuberance express itself in the inscription process :)

The stock cable, of unknown material, is light and supple.

I’m personally not a fan of the glossy black plastic casing on it, especially on a flagship product, although in fairness there are plenty of other TOTL manufacturers who do the same.

If it were up to me, I’d prefer to see a silver-plated cable to further beautify the IEMs. Kien is a master craftsman and artist, so it’s more about framing the masterpiece here :)

However, on the plus side, connectors and plug look classy, and the connectors have a bright red part to the right hand side 2 pin connector, which was helpful when plugging them into the IEMs (the red part is hidden from view once plugged in, and the natural shape of the IEMs makes it clear which side is which).

Overall, build quality is excellent and seems robust, and no issues with the finishing or hardware were found.

I found the fit to be excellent, with minimal protrusion from my ears and a shell size similar to that of iBasso’s IT01s IEMs and shape rather similar (but slightly larger in all dimensions) to that of the EE line up of the last couple of years (excluding the Wraith and Valkyrie).

The Sound:

As ever, my preferred method of testing is to try out the product(s) in question with a selection of songs from various genres and to let that process draw out the comparative strengths and weaknesses of each product, with a tl;dr summary at the end for those who lack the time or indeed willpower to listen to my audio ramblings :wink:

I have a few tracks which I’ve only found available on MP3; the rest are FLAC or WAV in 16/44 or 24/192, with a few DSD64 tracks thrown in because basically I’m just crazy like that :p
For the purposes of this review, I used the iBasso DX160 and the Lotoo Paw Gold Touch DAPs.

Without any further ado, let us dive in with reckless abandon :)

Hanson: Change in my Life (16/44 FLAC).

This is an acapella song, featuring harmonising of the excellent voices of 3 brothers who’ve been singing and performing together for about 30 years.
Straight away, a couple of the key qualities of this IEM stood out:

A fairly large soundstage with good separation, allied with great clarity and detail.

This is a song I’m very familiar with.
This is a useful test track for testing the midrange and seeing how well the IEM can handle the 3 voices, individually and as a group.

What stood out for me here, was the top-class separation and imaging.
It was noticeably easy to pick out the separate voices as they sang together, but whilst still retaining the resonance of their harmonising.

I had the feeling like I was almost standing in the amongst them as they sang. The vocals were positioned relatively central and forward (which is indeed exactly where they are positioned on the stage in this live performance, so I have to give credit to the Fusion for its very accurate spatial imaging here!).

I hugely enjoyed the timbre here. The Fusion has an enormously engaging tinge of lushness and richness across the spectrum, and wonderfully captured the individual timbres of each voice (not to mention the intakes of breath in between lines, and the sounds from the crowd in the background).

Eurythmics – Angel (HDTracks Remastered 24/48 FLAC):

This HDTracks remaster sounds superb generally.

The sounds of the acoustic guitar fingerwork/plucking and the percussion are crisp and detailed. Every detail here is shining. So much detail and clarity, superb layering. However, then the vocals come in, and stand out even more, with purity of timbre, taking centre-stage.

The Ataris – So Long, Astoria:

This high tempo pop-rock song features crunching guitars with lots of percussion. Not a bassy mastering, but an otherwise fairly dense ‘wall of sound’ kind of song.

However, this song doesn’t have a particularly strong bass in the mastering, which actually I feel is somewhat detrimental to the track, given that it’s a loud, driving rock song.

I think the Fusion did fairly well on this track. A mixed bag.

Like most IEMs, it’s not able to add a great deal to the low end (you’re looking at something like the twin-DD EE Nemesis, or a bit of EQ’ing on your DAP in order to achieve this).

However, it was still better than most, especially in the last minute of the song, where the sound gets a bit richer and more musical (on the song itself).

The Fusion avoids the pitfall of some IEMs I’ve tried with this song, which end up sounding a bit congested. The Fusion’s separation manages to offset the rather ‘closed in’ mastering in the song, whilst retaining all the melody and energy that makes the song so great.

Farhan Saeed & Shreya Ghoshal – Thodi Der (from the Bollywood film ‘Half Girlfriend’ OST. 16/44 FLAC):

This song is gorgeous.
It’s very pure, clear, beautiful. It takes a good combo of equipment to display this to perfection without letting the highs become piercing or strident in occasional places.

It starts with a high-pitched female vocal, then a deeper, but sweet male vocal, and at times harmonises both beautifully together. Very moving.

I hear very good timbre on both; the Fusion handles both the male and female vocals very well. The vocals are infused with a tinge of richness and warmth that really makes them shine. The background music has plenty going on with a variety of different stringed instruments, and these are all presented with the high-contrast forwardness I’m coming to associate with the Fusion.

Alison Lau – Handel’s ‘Il Trionfo del Tempo e del Disenganno’ (HDTracks 26/96 FLAC):

A staggeringly tranquil and beautiful piece of opera.
The singer, Alison Lau from Hong Kong, has a terrific and versatile voice, able from line to line to sing as low as a low blow from a lowbrow lowlife, and higher than a Woodstock-era hippie who just discovered a bundle of $20's in his backpack :)

Interestingly, whilst the soundstage and separation of the Fusion have impressed me with other tracks, here – surprisingly – it seems good, but not great. In comparison, for example, to my Stealth Sonics U9 (a fairly neutral/reference TOTL IEM with excellent technical performance and a holographic soundstage), it doesn’t wow me as much.

There’s also, for the first time, a touch of sharpness to the highest points of the vocals. In fairness, this would trip up many IEMs and isn’t a fault in the IEM itself; it just comes down to whether you want your IEMs to be more vivid or more relaxed and forgiving. Use of different ear tips and cables could alter this aspect of the Fusion’s sound signature however.

Sidney York – ‘Dick & Jane’ (from Korean drama ‘Age of Youth’ OST, 320k MP3):

Ha, this is a bizarre song. Foot stomping percussion (literally on this recording), madcap vocals, a ukulele, whistling, and a ridiculous bassline that oscillates wildly in a way that only The Smiths could comprehend.

It should be awful, but somehow holds it together for a goofy fun ride.

The combination of all these things make for a tricky customer for any IEM, but the Fusion is totally in its element here.

Yet again, ALL of those things I just mentioned are popping out. The ukulele and its timbre really stood out to me for the first time with this song; so musical and capturing all the details of the strumming, with excellent transients and decay. The Fusion brought out the detail of all the various things going on without ever losing its sense of balance and poise, or sounding congested, which would be all too easy to do with this track.

Again, great handling of the female vocal; timbre on point, engaging and forward.

Shawn Mullins – The Gulf of Mexico (16/44 FLAC):

So, this is one of my go-to tracks for critical listening.

This is a song that sounds terrific where there is huge soundstage and separation or shimmering highs. Ideally both; it really brings out the guitar strumming When there’s both, it’s stunningly good. My iBasso IT03 and IT04 IEM’s do this superbly, as did the Stealth Sonics U9.

Here, the song sounds very good, but not terrific. The soundstage and separation on the Fusion are big enough to handle that aspect of the song requirements. Timbre again is excellent, really presenting the sound of the bongos so faithfully, as well as the physicality of the guitar strumming.

However, through critical listening with this song, I’d describe the Fusion as more energetic and vivid than shimmering. More sparkle than shimmer, and more ‘vivid’ than either of those qualities.

Again, neither good nor bad; just a matter of what your preference is.

“Just the facts, ma’am, just the facts..” :)

Garrett Kato – Love is an Advert (16/44 FLAC):

Discovered this guy via the soundtrack of Australian/NZ tv show ‘800 Words’.

Really love this song; just good modern singer-songwriter stuff with a solid backing band. Very uplifting song.

The song has a fairly good level of low-end presence in the bass, low drums and parts of the guitar strumming on the lower note strings.

The Fusion really handled this well due to the tuning of its low-end.

Right from the start, the Fusion impresses here with how incredibly engagingly it presents the drums and bass and guitar strumming.

Yet again it seems like every instrument and every detail are popping out simultaneously. My mind is just noticing detail after detail, joy after joy.

Again, the (male) vocal is presented very well, full of character and capturing perfectly the slight raspiness in his vocal style.

It’s a fairly intimately mastered song, and I’d describe the Fusion’s soundstage and separation in this track as being very good, but again just slightly less than that of the IEMs that perform to a world-class level in this aspect.

Dire Straits – Sultans Of Swing (DSD 64):

One of my go-to test tracks for testing (and just listening), and I know several other reviewers on here share this point of view :)

A terrific song, with lots of things to get analytical over; percussion, timbre, guitar fretboard wizardry etc.

So right from the beginning, we have a kind of strummy/plucked guitar riff, with another guitar solo-ing over the top.

Here again, the slight lack of shimmer doesn’t gel with this aspect of the track quite as well as other IEMs I’ve tried.

Again, at the risk of sounding like a broken record, vocals are superbly presented. Front and centre, really bringing out the unique timbre and character of Mark Knopfler’s vocals.

The energetic character of the Fusion again shines with this song, with it’s foot-tapping, head-bobbing driving rhythm.

There’s a natural shimmer in the mastering to this song I feel, especially with the strummed guitar, tizzy percussion and so forth, and even more so at the end. Whilst I have said that shimmer doesn’t seem to be a quality that’s particularly innate to the Fusion, nevertheless, it presents very faithfully what is already there in the track, and overall, it’s a very involving presentation of this track that just puts a smile on my face :)

The joyous twiddly guitar solo at the end is just infused with so much crispness and intensity.

Anberlin – The Art Of War:

This is an immense track. There’s so much going on in it and so many things to zone in on when listening. There’s powerful percussion and bass, a driving rhythm, synths and sound effects and over all this, great vocals, searing lyrics and simply majestic rock!

In terms of analysis of detail retrieval, on this track, around 9 seconds in, there’s a sudden sense of space opening up in the upper-central zone of the soundstage, along with a faint, almost imperceptible hum.

I don’t know much about music production, but I’m guessing this is the ‘channel’ being switched on that the bass guitar is linked up to (as indeed the bass comes in at the same spatial location a second or two later).

This small detail of the channel opening up for the bass at 9 seconds in is captured very noticeably on the Fusion.

From the start of the song, again, there’s just immense power and authority to the pulsing synthetic percussion effects and with every instrument that comes in afterwards. The impact, rumble and vibration as the strings are played on the electric bass is presented with outstanding realism and is so, so engaging.

As with every other track, all the instruments and effects are vividly standing out, but the tuning of the Fusion mean that vocals still manage to take centre stage from the moment they begin.

Billy Eilish - Bad Guy (16/44 FLAC):

Woah! Dat bass :p

Yeah, this is not an anaemic or neutral-reference IEM.

That bass is powerfully tuned in the song, and it’s so deep in the sub-bass on the Fusion. Then the sinister vocals come in, and again, that forwardness and immediacy in the presentation of the Fusion just makes them send shivers down my spine! Yet again, everything in the song is popping out with such vividness and energy. I should just start copying and pasting by now. Duh! :p

Buena Vista Social Club – Chan Chan (24/96 HDTracks FLAC):

This was the first track I actually listened to with the Fusion, using my (relatively) budget – but still very good – DX160 DAP.

I can honestly say I was astonished, fresh out of the box.

Everything was popping, engaging, rich, spacious, detailed.

There’s an instrument (some kind of bass I think) that comes in with a doubled up noise at 2 seconds into the song. The Fusion renders it with depth and authority. There’s bongos, congos and various kinds of percussion going on in the background and the Fusion captures them all with marvellous clarity, separation and imaging.

The different vocals are positioned centrally, very slightly forward and – spatially - spread out slightly to the left, right and centre; the Fusion surprised me with how well it separated out each vocal part and let me distinguish each singer clearly in a way I’ve never heard before. That’s a seriously good technical performance, and the timbre on each of the male vocals – especially the deep bass one – was top class.

There’s a light and delicate tactility to the guitars, the picking of the steel guitar and the fingerpicking of a different, acoustic guitar.

It’s that dynamic driver physicality that really adds to the realism of the timbre, and here on the Fusion it’s executed with delicacy and gracefulness.

The soundstage is wide, with good depth and height, and excellent layering. It seems to strike a very good balance between providing separation and air around the instruments and vocals and allowing a degree of intimacy in the performance.

Final mention must go to the brief trumpet solo, which comes in at 02m37s.

It’s a good test of an IEM (especially with my treble sensitivity); can it present it without being wince-inducingly sharp, but without losing faithful reproduction of timbre and the heart-aching emotion of the moment?

In the case of the Fusion, it very much walks the line on the edge of sharpness for me here, but just manages to stay on the right side of it.

The trumpet sounds great.

I should add that upon listening to this track (and indeed most other tracks) with the Lotoo Paw Gold Touch really made the Fusion shine.

It audibly scales up in quality with a TOTL source; greater clarity, detail, improved technical performance and a slight ‘opening up’ of the whole soundstage.

Summary of the sound signature:

It's probably just my personal bias, but I always feel faintly cheated and offended when I encounter a dynamic driver IEM that doesn't have walloping bass, given the ability of the DD technology to deliver a stunning, visceral, tactile low end.

It seems like an affront against nature or something; like buying a specific high-power DAP because you need the extra power to drive your headphones, only to find someone has slapped a volume cap on it :p

The low end I’d describe as being tuned reasonably above neutral, with a fair balance between sub-bass and mid-bass. It has the sub-bass impact and physicality of the dynamic driver that brings the life and energy into the music you play on it, along with the warmth and richness from the mid-bass and the general tuning of the IEM, which brings that quality of lushness and engagement with the music.

The mids are well balanced, and strike me as being forward if anything. Timbre is excellent, especially with vocals which always seem to take centre stage.

The treble is clear and vivid, rather than delicate and shimmering. It has good extension and a reasonable amount of air.

Detail levels are excellent. Spatial imaging and layering are similarly great. separation and soundstage are excellent too, with the caveat that there are other TOTL IEMs that just have an edge here with regards to these qualities.

There’s a lovely degree of note thickness and weight, without ever becoming cloying or muddy.

I’d have to finish this section by saying that everything on the Fusion just pops, as if the contrast and vividness have both been turned up to 11.

The experience is insanely enjoyable for me, but there’s so many details and engaging aspects grabbing my attention..

It’s enormously engaging most of the time, but I think the cumulative effect from extended listening sessions is – to employ a pugilistic analogy - a bit like trying to repel multiple attackers coming at you simultaneously from several directions :p

Cable swap!

I found that using the Eletech Prudence SPC cable with the Fusion was extremely rewarding. The Prudence definitely provided an increase in bass definition and impact, adding a touch of extension and air to the treble, and overall a boost to the technical performance. Generally, it gave it a slightly more balanced and even tuning overall.

It’s an interesting effect in that it doesn’t seem to compromise that vivid, hi-definition sound; if anything, the added clarity and definition enhance that quality, and yet I did feel that the occasionally overwhelming ‘all dials turned up to 11’ nature of the Fusion was alleviated with the Prudence in some strange feat of wizardry :)

I’m genuinely struggling slightly to say whether I can define the Fusion as TOTL or not. I think my overall feeling is that, yes, it is. It provides an experience that I haven’t really had with any other IEM, at any price point.

However, the doubts, I suspect, are in part due to the perception of what TOTL constitutes. Years of having ‘neutral-reference’ perhaps held up (in some quarters) as the model of what TOTL means is probably an influence in this.

But the Fusion does so much so very, very well (and I’m talking world-class here).

It certainly does ‘addictive enjoyment of the music’ better than plenty of other TOTL IEMs I’ve heard, and shouldn’t that be one of (if not THE) prime standard against which any IEM is judged after all?

Yes, there are IEMs which have a more holographic soundstage, or more extended and shimmering or sparkly treble. But then, thinking back, they didn’t have the same character and engagement that the Fusion brings.

There’s not much I can compare it to, because it does sound a little bit different to everything I’ve heard so far.

Of my existing IEM line-up (or those I’ve heard a lot recently), it combines the gorgeous musicality, engagement and enjoyment of the USD $499 Stealth Sonics U4, with the energy, vividness and intense fun of something like the EE Nemesis or Legend X or Valkyrie (but not quite so much bass as the first two).

I’d say Legend X and Stealth Sonics U9 have the edge in terms of technical performance (and bass impact and rumble, in the case of the Legend X).

The U4 has a similar level of musical enjoyment and engagement, but a significantly more relaxed, smooth and forgiving sound signature.

So, as ever, we come back to “it’s all about your own preferences” :)


I can begin with the standard kind of disclaimer that, as with most good audio equipment, it’s all about one’s own sonic preferences.

This is an IEM that seems to me like it has the dials turned up to 11, all of the time. Honestly, it does get a bit fatiguing for me sometimes, but then as I’ve mentioned, I do have a known sensitivity to treble (possibly other things) and am prone to this.

This caveat aside, this IEM may – for my sensitivities – not be here for a long time, but it is very much here for a good time :D

It’s just amazingly enjoyable and engaging.
Stunningly vivid and with details popping out everywhere.

I’d imagine if someone from the 1980’s fell through a wormhole and ended up watching UHD TV in our present time, this might be something of the feeling they’d experience.

Just as with hi-res video, now that I’ve experienced this IEM, I can’t imagine not having it in my line-up to listen to daily.

Summary (TL; DR) :

The Fusion offers a rather unique flavour of TOTL performance (or close-to-TOTL, perhaps, depending on one’s views on such things) at a very competitive price.

It sounds to me like it has all the dials turned up to 11 :D

It is stunningly vivid, musical and engaging across all parts of the sound spectrum, with a solid technical performance underpinning all that.

A wide soundstage, with good depth and height combine with a high standard of imaging and excellent separation.

It has an impactful and authoritative low-end, which helps to engender the lush and engaging tone that informs the mids and treble.

It responds to cable pairings and tip rolling, so there’s always scope to tweak the sound signature a bit to your preferences.

This is an IEM that really emphasises enjoyment of the music, and if that’s what you’re looking for, this is an IEM that I seriously recommend you to look into.
Great review, thanks! The cable somehow reminds me of the stock cables Noble / 64 audio use :)
Not the world's first for magnetostatic driver iem , earbridge E70 is the first
The market is so big, hence why I carefully said "possibly a world first", haha. Thanks for letting us know :)
Pros: Exceptionally good build quality
- Sound quality - Open, rich, dynamic, energetic and exciting sound
- Shell customization designs
- Good integration of the magnetostatic driver
Cons: Lack of variety/options in stock ear tips necessary for snug fit.
- I personally love the treble but treble sensitive people should tread with caution since appreciation will depend on preferences and threshold of treble sensitivity.
My background - I am a professional musician, producer and audio engineer with experience in the performing, recording and pro-audio industry. I test products on a technical and musical level and try to write reviews as simple as possible from a music fan's perspective.

Genre preferences - I majorly listen to rock, acoustic, pop and metal and occasionally listen to EDM songs which are doing the rounds on the radio and charts.

Disclaimer -
I would like to thank ItsFit for sending me the Fusion to test and review. I am not affiliated with the company or any of its sellers and write this review with an unbiased opinion regardless of how the review turns out.

Links – ItsFit Website | Fusion ($950)

Fusion can be ordered as universals or customs. Itsfit offers numerous shell and faceplate customization options where imagination is the limit.

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Genre preferences - I majorly listen to rock, acoustic, pop, metal, and occasionally popular EDM songs.

About Itsfit - ItsFit is a Vietnamese company, who have been re-shelling IEMs for the last 3 years and only recently launched two of their own IEMs, R3 and Fusion. In my opinion, ItsFit is a brand to watch out for as they have good R&D experience, interesting tech in their IEMs and some of the most attractive shell designs I have come across. They regularly receive high praise for their re-shelling and recently Fusion has been making waves too.

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Technical Specifications -
  • Configuration – 1 Magnetostatic (Treble) | 2 BAs (Mids) | 1 DD (Bass)
  • Freq. Response: 4Hz – 40kHz
  • Sensitivity: 98 dB/mW @ 1kHz
  • Impedance: 13.1Ω @ 1kHz
  • Isolation: -26dB
Included in the box - ItsFit packaging is minimalistic but cool, as they focus on the things that are important; stuff that you’ll actually use.
  • In-ear monitors
  • 2-pin cable
  • 2 sets of ML ear tips
  • Hard case
  • Carrying pouch
  • Cleaning cloth
  • Cleaning tool
  • Handwritten welcome cards
  • Warranty card
Packaging 1.jpeg Packaging 2.jpeg

Build Quality - ItsFit IEMs have fantastic build quality, period! They also have some of the most interesting and attractive shells designs in the industry that I’ve come across. Fusion has three vents which look like grip holes in bowling balls. IMO, it is a very interesting design for dynamic driver venting. It not only serves its purpose but also looks very cool!

It is made out of resin and has very cool nozzles that are transparent and different from the shell color. They kinda look like a different part that is glued to the main shell but I don’t know if that is the case or not because it is very well integrated. As you would expect from a company that solely provided a re-shelling service for a few years, the shells have absolutely no bubbles or residue glue visible. The shell customization I requested for Fusion came out perfect! You can see for yourself how good it looks in my pictures. They came out equally great!

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Picture Courtesy - Kien @ ItsFit

Cable – Fusion comes with a silver-plated copper cable which feels and looks very good. It has nice looking and very solidly build connectors and jack. I love the grey-ish color they have. Cable has a nice braid and very little microphonics. Though I’d love to see an UP-OCC kinda cable included with Fusion, I actually have no problems with the stock cable.

Hardcase – The included case is similar to what comes with 64 Audio IEMs. I personally like these cases since I’ve been using them for a lot of years.

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Fit and Comfort - Fusion's shells are semi-custom shape and are small enough to fit most ears. But the fit and comfort completely depends on the choice of ear tips. What makes ear tips difficult to choose is that Fusion's sound signature is a bit tip dependent and changes with snugness of fit. So you gotcha mix and match and see which ear tips sound the best and which provide the best fit. The ItsFit semi-custom universal shells aren’t as ergonomic as the ones from Fearless or BGVP as the latter work pretty well with multiple types of ear tips. In my case the nozzle needs longer ear tips for a snug fit. Though if you choose the right ear tips, ItsFit shell can fit as snugly as the ones from the other two companies. So choosing the optimum ear tips is important. Sadly, ItsFit do not provide a variety of ear tip options in the package. So, having a collection of different kinds of ear tips will help.

Here are some ear tip options that I settled on.

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Snuggest Fit
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Best Sound

Noise Isolation - The ear tips that provided the snuggest fit of course had the best isolation too and the isolation was as good as it can get for a universal shell. Though Fusion’s noise isolation is slightly less because of its vented design.

Sound Analysis – Fusion has a nice quirky fun tuning which makes songs that you’ve been hearing for a while suddenly become livelier, more energetic and fun. Fusion being a tri-brid has 3 different kinds of drivers and each driver pitches its own character in a very nice way. It is highly resolving, open sounding and dynamic, which makes it highly addictive. I funnily think that it is the best sounding IEM in my collection for Karnivool’s Sound Awake album, which is one of my favourite progressive rock albums. It is as if Fusion was tailor made for that album. Haha.

Let’s dig in deeper to know more…

Note – Fusion's sound signature changes slightly with different ear tips and fit. It shines exceptionally with some. So, I suggest you tip roll and experiment as the sound can vary between bright to balanced to slightly warm depending on your choice of ear tips. I’ve used wide bore softer silicone ear tips for the sound analysis.

Kien Fusion 1.jpg
Picture Courtesy - Kien @ ItsFit

Bass – Sub-bass has very good extension down low and in fact has more presence than mid-bass. I had gotten so accustomed to mid-bass leading the charge that Fusion sounded the good kinda different to me in the first listen in comparison to other IEMs I was testing. Sub-bass has more character than rumble, though it can rumble pretty well too if a song demands. But character is what wins for me. Mid-bass has good presence too and overdriven bass tones of bands like Karnivool, I Am Giant and Muse sound super crispy and snappy. Bass overall has more lively character than dominating presence. It is well defined, fast, dynamic and even sustains pretty well. For example, bass in Twenty-One Pilots’ Hype’ and Walk the Moon’s ‘Shut Up and Dance’ has very good character, deep sub-bass, crispy mid-bass presence and punch while still staying more fun kinda neutral rather than overpowering.

Mids – The transition from mid-bass to the midrange is very linear. Mids are highly musical, have very natural timbre along with great resolution and clarity. The balance of mids though is pushed a bit behind bass and treble. Midrange body is neutral-ish, though neither too full nor too thin. Upper mids have 2 primary peaks, one around 2.5-3kHz and another one around 5kHz defining the upper midrange character. Vocals are exciting and lively and even background vocals in songs like Coldplay’s Orphans have great resolution and clarity. Drums sound more lively than warm/earthy. Guitars and orchestral instruments have good attack and presence with a neutral body and very lively natural timbre, owing to Fusion’s linear lower mid-range and good shine in the upper mids.

Treble – Fusion’s highlight and USP is surely the Magnetostatic driver. I had only heard of Magnetostatic drivers in theory but had never come across one in action until I got the Fusion. The treble extends very well, is super crisp, open and sparkly (the good kind)! It contributes majorly to make everything sound exciting and livelier. Cymbals sparkle a bit more than neutral, though do not get splashy. Vocals have good rich sparkle and acoustics have that extra zing. The Magnetostatic treble character though is unlike BAs or DDs and so might need some getting used to. Once you adapt to its character, you’ll see how well it integrates into Fusion’s signature. But treble sensitive people should tread with caution (always), since appreciation will depend on preferences and threshold of treble sensitivity. Also, as I stated previously, Fusion’s treble character changes a bit with different ear tips and I highly suggest tip rolling for best results. I initially needed a bit of ear burn in, 5-10 songs maybe. My excitement levels were rising song by song and by the end of my ear burn in period, I was enthused and was already onto checking all my favorite songs and how they were sounding on Fusion. It is now one of my go-to IEMs to listen to music every day.

Soundstage, Imaging and Separation - Fusion has a nice big, wide and open soundstage. Width and depth both are very good. Imaging is very precise and pinpointing even the quietest instrument in the mix is quite easy. As for separation, Fusion much like Shozy Pola39, shows that great results can be achieved by selecting best drivers for the job and good tuning talent.


Comparisons -

CustomArt Fibae 7 ($1100) – Right off the bat, Fusion sounds more modern, energetic and exciting whereas Fibae7 is warmer of the two. Fibae7 has warmer bass and slightly stronger feeling of bass impact whereas Fusion has more sub-bass and dynamics. Fibae7 has a Harman kind of dip in the mids whereas Fusion has a more linear approach. Fibae7 has substantially more upper mids presence with a forward presentation than Fusion. Fusion on the other hand feels more natural and lively there. Fusion’s treble is more extended, present and lively whereas Fibae7 has a natural roll off post 5-6kHz. Both have nice wide soundstages. Choosing one between them completely depends on your preference and liking.

Fearless Roland ($1000) – They are polar opposites in a way. Roland is a darker IEM whereas Fusion is energetic and lively. Fusion has more sub-bass as well as overall bass presence. Roland is quite reference like from bass to starting of upper mids. Post that, both have good upper mids presence but Fusion because of its livelier signature, has more resolution in the mids as well as overall. Fusion’s treble is way better extended and open whereas Roland has a sudden treble roll off post 5kHz. Fusion has a livelier open soundstage whereas Roland has a decently wide soundstage but because of it being dark, the feeling of openness is subdued.

Shozy Pola39 ($950) – This is a tough one! Both Pola39 and Fusion have their own characteristic treble character which is their strength and also what makes them uniquely cool. Fusion has a magnetostatic driver for treble whereas Pola39 has a dual EST driver. Both have a very good bass character and presence from their respective dynamic drivers but Pola39’s is a bit more present while Fusion’s is more controlled. Both have good natural mids but Pola39’s mids sound slightly warmer and balanced whereas Fusion’s mids are slightly pushed back but equally dynamic and punchy. Pola39 sounds slightly warmer till the treble as compared to Fusion and then both of them gain their characteristic treble character where Pola39’s is more open & airy and Fusion’s is slightly fuller and ever so slightly upfront in comparison. Both have a nice wide soundstage. Choice between the two is tough as they both have a similar take on a ballpark idea of sound but still quite different and cool in their own way.

BGVP EST8 ($799) – EST8 and Fusion are again quite different. Fusion sounds very modern, energetic and lively whereas EST8 sounds warmer. Both do bass very well but Fusion has a dynamic driver with higher resolution, nicer character and energy. Fusion has better mids with more resolution, better details and more liveliness. Fusion’s treble has more sizzle, sparkle and energy whereas EST8 is smoother, more natural and warmer.

Conclusion - ItsFit is not a new company as such. They’ve been re-shelling for the last 3 years while doing R&D on the side to develop their own products. What is amazing is that instead of choosing a safe tuning for their first products, they in fact got experimental with new driver tech (Fusion) in one and reference style tuning (R3) in the other. Both are not easy to execute! Fusion is a very lively and exciting IEM which makes your music feel extra special. Also, it can be ordered as universals or customs and you can take my word that their designs, shell quality as well as finishing is one of the best in the industry. Fusion gets 2 thumbs up from my side. If your budget is around its price, surely give it a shot.


Gear used for testing and review -
  • Logic Pro X session with hi-res test tracks played through Universal Audio Apollo or Focusrite Clarett Pre X audio interface headphone out.
  • Hiby R6 Pro
  • Oneplus 7 Pro
Reference Songs list -
  • Foo Fighters – The Pretender, Best of you & Everlong
  • Coldplay – Paradise, Up in flames, Everglow, Orphans
  • Dave Matthews – Shake Me Like a Monkey
  • Ed Sheeran – Thinking out loud, Bloodstream & Galway Girl
  • Chainsmokers – Somebody, Sickboy, This Feeling & Closer
  • Twenty One Pilots – The Hype
  • John Mayer – Slow dancing in a burning room, Stop this Train & Say
  • Gavin James – Always & Hearts on fire
  • Switchfoot – Meant to live & Dare you to move
  • Linkin Park – Papercut, Somewhere I belong & Talking to myself
  • Walk the Moon – Shut Up & Dance
  • Lifehouse – All in all & Come back down
  • Niall Horan – Slow Hands, Mirrors & The Tide
  • Breaking Benjamin – Diary of Jane
  • Karnivool – Simple boy & Goliath
  • Dead Letter Circus – Real you
  • I Am Giant- Purple heart, City limits & Transmission
  • Muse – Panic station
  • James Bay – Hold back the river
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