Itsfit Labs Fusion – magnetostatic mayhem


Itsfit are a Vietnamese company, based in the capital city Hanoi. It was founded in 2016, growing out of a small sound and audio components laboratory into the custom IEM manufacturer it is today. They specialise in custom IEMs, earning a good reputation as a resheller of other manufacturer’s IEMs into CIEM form and more latterly for their own line of in-ear monitors, available in both universal and custom form.

All the IEMs are hand made and can be customised in terms of design to match whatever the client can imagine – some of their previous universal and custom IEMs are genuinely beautiful creations, highlighting the best of classic Vietnamese hand-crafting alongside cutting edge sound design.

I first came across the brand being mentioned on Head-Fi towards the end of 2019 in one of the TOTL threads, as they were conducting a 30% off sale to celebrate the birth of the daughter of Mr Nguyen Trung Kien, the Itsfit founder and chief designer. I was immediately intrigued as I was awaiting the birth of my own daughter, so taking that as a sign from the audio gods, I put in an order for their flagship model, the Fusion.

Apart from some correspondence to identify when exactly my new goodies would be landing, no incentive or input has been received from Itsfit for this review – the gear is my own purchase, and the words that follow encapsulate my own thoughts (and ramblings) on the Fusion.

Tech Specs


The Fusion arrives in a long thin black cardboard box, devoid of any writing or graphics apart from a silver Itsfit fingerprint logo in the middle of the box lid. It’s a simple but elegant start, looking understated but not cheap. Opening the box, you get more logos, one on a small velour IEM carrying bag and another on a small satin scrap of cloth that covers the top half of the box. Moving the bag reveals the solid metal Itsfit puck case that serves as the main IEM carry case (again with the Itsfit logo and some nice personalisation text with the owner’s name). Moving the fabric reveals a nice card insert with a handwritten “Thanks for purchasing” message, and getting past that reveals the IEMs themselves.

The tips and cable are neatly packed inside the puck, so it’s a pretty basic but very nice looking package, and certainly not one that looks like it comes from a company that is just starting out on the IEM manufacturing journey.

Build and ergonomics

The Fusion are built from acrylic in a pseudo-custom design, with some gentle contouring on the inner face of the IEM to conform to the shape of the average user’s ears. There is no getting around it – these shells are DEEP, with a relatively short nozzle but a thick body which sticks out a few mm from the outer bowl of the ear when worn. The bore itself has three sound tubes, and this is matched by a triple-holed vent on the top of the IEM shell, matching the pattern in the nozzle almost exactly. As mentioned, the pseudo-custom design means that the Fusion is never anything less than a comfortable fit for me, but it doesn’t “lock in” to the upper part of the ear like a true custom or some of the more aggressive universal designs like the Ibasso IT03. I relay on foam tips to fix the Fusion firmly in ear, as due to the size they can otherwise move a little in everyday use with some of my usual silicon tips. It should be mentioned I have particularly large ear canals, so someone with a more average lughole size will probably find this less of an issue.

The build is top notch, with the shells feeling smooth to the touch and exhibiting no obvious flaws or imperfections in manufacture. My pair have a piano black body, with a seamless blend into a “galaxy” style faceplate with inlaid blue and silver-grey glitter fragments in an intricate pattern. The design is recessed slightly into the faceplate, seeming to hover just under the surface, giving a nice impression of three-dimensionality to the design. The shells are finished off with a silver Itsfit fingerprint logo on the left shell and the company logo in text on the right, again in silver. It’s fair to say that these are beautiful looking IEMs, and some of the nicest looking in my personal collection. The team at Itsfit have put some stunning designs in their look book (the Koi Pond and the lava/magma style shell are favourites of mine), so if you have something specific in mind I’m sure it will be worth speaking to the company to see what they can do for you.

Regarding comfort, the Fusion are a very amenable IEM, sitting happily in the ear for extended listening sessions without any major discomfort. The included cable helps here, with a simple twisted braid and some well-moulded heat shrink over the ears to keep the cable draped neatly. Unless you need to wear your IEMs while laying down on you side in bed, I can’t see anyone having a major issue with the design they are using here.

Initial impressions on sound

The Fusion are one of an increasing raft of “tribrid” IEMs hitting the market, but unlike most of the recent high end releases, they are utilising a magnetostatic rather than electrostatic driver array to provide the treble, complementing the more traditional balanced armature and dynamic driver sitting underneath.

I haven’t heard any other magnetostatic models at time of writing, but if this is an indication of the potential inherent in this style of tweeter setup, I sincerely hope this isn’t the last one I cross paths with. The Fusion manages to sound both coherent and “different” at the same time, with a smooth and seamless transition between each of the three driver types as the frequencies rise and a tonality in the upper registers that doesn’t sound quite like a traditional balanced armature or dynamic driver. It carries both weight and fizz, bringing an undeniable brightness to the signature, but not in a harsh or brittle way. The net effect is a peppering of the high end with plenty of crunch and sparkle, but without the fragility or heat that sometimes accompanies these characteristics. It’s a nice blend, and something that diverges from a lot of what the current market is offering.

In terms of tuning, the overall impression I get from these IEMs is a gentle U, with the bass and treble sitting slightly in front of the midrange in both position and overall quality. This is an assessment that comes with a heavy caveat, though; the Fusion is one of the most susceptible IEMs I have heard to tip rolling, allowing for some pretty good fine tuning of the overall sound with the right match of tips.

Bass is solid but not hugely north of neutral, with a solid sub bass emphasis that adds heft to the underside of notes and a real physical presence. The DD packs some appreciable rumble and solidity, but the comparatively leaner midbass presentation allows the Fusion to concentrate on low-end texture and detail rather than all-out presence. It also allows the dynamic driver tuning to focus more on speed, with the tight delivery keeping pace well with the balanced armature and magnetostatic drivers sitting above it.

The carefully judged mid-bass dip lends the Fusion its overall neutral-natural tonality, keeping the stage reasonably cool and airy. The transition into the midrange is well handled, the drivers handing over seamlessly to provide a very coherent sonic image. The midrange is probably the least flashy element of the Fusion, sitting behind both the bass and treble and going about business with a workmanlike efficiency for the most part. That isn’t to say that the mids are lifeless – far from it, these are some very textured and emotive sounds, but they just don’t quite achieve the excellence at either extreme that the Fusion’s other drivers exhibit.

Body is somewhere around neutral, with vocals possessing enough heft to sound natural, but lacking the chestiness or saturation that you get on “meatier” sounding IEMs. Detail is also somewhere between good and excellent for the price bracket, with the Fusion resolving fine details in tracks with ease. It isn’t the most detailed tuning you can get for this sort of price, but it doesn’t leave you feeling short changed either.

Guitars have more bite than chug, lending themselves well to rockier genres when you need that blast of energy and fizz. Piano and keyboard sound decent, but lean more towards the cold and analytical side, sitting a little behind the vocals in the staging. The overall timbre is just lacking that last bit of warmth to come across as fully natural, but still sits quite squarely in the “realistic” bracket, without any exaggerated colouration in the main body of the sound.

The star of this particular tuning is delivered by the magnetostatic driver, with the Fusion delivering a crispy and crystalline treble experience that is not quite like anything else I’ve heard. It sits somewhere between the classic sparkle and bite of a balanced armature treble and the effortless solidity of the newer electrostatic hybrids, presenting treble that is both ethereal and effortless at the same time. This is definitely an IEM that leans towards the brighter end of the spectrum in both presentation and sheer quantity of treble, but as someone who typically favours a darker and smoother upper end, I don’t find the Fusion fatiguing in the slightest. Cymbals are beautifully crisp and defined, but possibly trend a little towards over-emphasis – if you don’t like the sound of steel percussion accentuating the upper end of your music, these probably aren’t the IEMs for you. As well as being suitably energetic, the treble is also quick, with the new driver tech resolving individual bow strokes of violins and single cymbal strikes with a speed that even my all-BA in-ears can’t quite match. There has been a lot of stuff written in the last 18 months about the rise of the e-stat for in-ear monitors, but I’m going to go out on a limb and say that I think the future of treble for IEMs is firmly with the magnetostats – the sound blends the best elements of all the different driver tech that has gone before and creates something genuinely different.


As outlined above, this isn’t a basshead monitor by any stretch of the imagination. The Fusion presents a sound that is grounded but not ground-shaking, with a solid presence in the sub-bass. Starting at the lowest end of the spectrum, extension is good, with the 10mm DD providing a decent level of physical thump to “Why So Serious?” from The Dark Knight soundtrack. The bass isn’t as ominous as it can sound on something like the IMR Rah or CA Atlas, but the omnipresent thrumming in the track is presented with enough power to give the track the physical presence it needs, Similarly, “Heaven” by Emile Sande renders well, with the pulsating bassline that kicks off the track carrying decent weight, and generating a genuine physicality as the drivers vibrate.

Moving up to the mid-bass, “Freak On A Leash” by Korn is next up. Properly rendered, the bass drop at the 3:02 mark in this track can make the hairs on my arms stand up. The Fusion doesn’t quite manage this, but does manage to lend the bass plenty of weight, hitting with a solid physical slam in the eardrum. On monitors with more of a mid-bass thumb, this song can almost induce an ice-cream headache with the constant “whuuuunnnnggggg” of Fieldy’s detuned strings, but the Fusion doesn’t quite reach those levels, settling for a mild tickling in the frontal lobes instead.

Bass texture is excellent for the sub-£1000 price bracket. “We Shall Not Be Moved” by Mavis Staples is a glorious mixture of gospel choruses, fuzzy and distorted single string bass and a male baritone in the backing singers who is probably couldn’t sing any lower if he recorded his lines in a basement. The Fusion blends each element together expertly, dusting each different strand with a fine layer of texture like old certificate paper. Each note has plenty of space to breathe, the layering and control definitely leaning towards top tier in terms of performance.

“Hello, It’s Me” by Sister Hazel is another track that comes out well, the serpentine bassline that drives the track coming through with a dry flexibility that captures a little dash of the unctuous wetness that defines the song on some bassier monitors but still keeping the bassline taut and almost powdery in texture. It allows the listener to imagine the space around the notes, creating an impression of tightly wound bass guitar strings vibrating and fingers sliding up and down the fretboard.

The emphasis on texture means the Fusion isn’t overly wet or particularly emotive in feel, so it’s probably a more analytical than romantic presentation. The technical capabilities are definitely impressive for a single dynamic driver, with the Itsfit team doing a great job balancing froth and precision to complement the rest of the tuning.

Playing “Disc Wars” from the Tron: Legacy soundtrack is another good indicator of the level the Fusion can achieve. The track is underpinned by a pulsating synth line that suits just above audible in the frequency spectrum, and the Fusion captures just enough weight from this to fill in the space underneath the rest of the sound. The orchestral percussion and strings sound solid and rich, capturing the changing dynamics of the song, allowing the track to ebb and flow in the ear in a manner reminiscent of the excellent M-dome over-ear drivers from the Elear and their other high end models. This sense of dynamic shift injects some much needed life into the overall presentation, which would otherwise run the risk of being too analytical or sterile.

Coming on to bass tonality and weight, “The Chain” by Fleetwood Mac is another all time favourite. The iconic bassline that kicks in at 3:02 (what is it about the 3 minute mark for some of my favourite tracks?!) builds well with the drums underneath, feeling planted and solid in the ear as the tempo ratchets up. It lacks that last bit of physicality and substance the song can eke out of a large planar over-ear from the likes of Audeze, but for a 10mm DD, it gives the sound more than enough heft.

My final test track is “Bad Rain” by Slash, which has an opening bass riff that has so much attitude and passive aggression under the surface it could probably pass for a teenager in most modern households. The kick and snare drum head impacts of the opening few bars hit with genuine energy, placing more emphasis on snap rather than all-out slam but still providing the right amount of punch to drive the song along. When the bass guitar joins the party, it feels almost feral, the Itsfit flagship emphasising the snarling texture and distorted fuzziness over sheer volume, giving the bassline plenty of air around the vibrating strings. It works in terms of bringing out the fine detail, but can feel a little less bombastic than the track can sound with a few extra low end dBs.

Overall, this is a well judged bass tuning that walks a slightly different path to the typical V shaped sounds it there. Solid enough to capture the essence of the DD, but fast and detailed enough to keep pace with the drivers sitting overhead. It won’t be enough quantity-wise for the serious bassheads or warmth lovers out there, but for listeners who appreciate texture and detail as well as slam it works pretty well.


The midrange on the Fusion can be a little tip dependent, varying from slightly recessed to pretty neutral in terms of position. It is handled by the dual-BA drivers, and is a classic example of an armature-led sound, with plenty of definition and crispness.

Detail levels are kept at a similarly high level as the bass, although the Fusion is not an absolute detail monster compared to some of the £1k+ monitors out there at the moment.

Note weight leans towards neutral, which combines with the placement to leave the Fusion with a midrange that sounds compact and tight, erring towards dry in parts. It isn’t the last word in terms of note size, and definitely doesn’t have a huge amount of body in the notes, painting the sound with an enjoyable but lightweight texture.

Throwing some Blackberry Smoke onto the playlist, the main riff in “Restless” carries a sense of muscular swagger, but doesn’t feel quite as big as it can on denser sounding IEMs like the JH Diana. The Fusion capture a good sense of energy with the jagged edges of the main refrain, but just lacks that bit of fatness to the chord progressions that the song can evoke. “Rhymes” by Beth Hart and Joe Bonamassa sounds the same, with the veteran bluesman’s guitar bouncing jauntily through the track, sounding a little light compared to the chunky horn refrain that accompanies the chorus.

Sticking with rockier fare, my usual Slash test tracks benefit from the energy of the midrange, “World On Fire” buzzing in the ear like an angry chainsaw. The quickfire guitar riff consists almost entirely of edge and vitriol, the lightness of the notes helping the Fusion step nimbly through the track without any hint of slowing down. Similarly for “Shadow Life”, the staccato rhythm that kicks in at the 40 second mark is blisteringly fast and crisp, trading weight for fizz. The Fusion don’t hit you with sheer weight or density of sound in the midrange, but for rock and other guitar based genres, this actually works pretty well. Riffs growl and bite when they need to, and the dual BA handles everything with impressive speed.

In terms of vocals, the Fusion again sits fairly neutral in both staging and emphasis, putting the singer on par out just behind the bass and treble in the mix. There is a good balance between male and female singers, with the Fusion presenting both with plenty of texture and clarity. Again, this is a monitor that emphasises texture over weight, so it won’t provide the most soulful rendition you’ve ever heard, but it still manages to engage the listener. Vocal intonations are crisp and distinct, with the Fusion rendering the finer sounds around the edge of the singers voice nicely.

Chris Stapleton is always a go-to when looking for sibilance in an IEM, with his distinctive gravel-throated delivery sounding somewhat like someone gave a mountain a microphone and told it to gargle with boulders. The usual hotspots in the chorus of “Whiskey And You” are still there on the Fusion, skirting the border of unpleasantness but not becoming unlistenable. Stapleton’s voice is all edge and rawness here, the lack of meat in the middle placing the emphasis on the jagged edges of the delivery. If you feed the Fusion raw and spiky fare, it won’t hide it – this is an IEM that won’t play brilliantly with poorly mastered or hot recordings, but it doesn’t add any additional heat of its own here either.

The other tester I use for midrange harshness is another Slash track, this time his “Starlight” collaboration with the helium-voiced Alter Bridge frontman Myles Kennedy. The track starts with a deliberately dissonant guitar intro laden with harmonics, which the Fusion handles with bite but no aural discomfort. As the track winds up, so does Kennedy, getting into true dog-bothering vocal territory as the chorus kicks in. Again, the Fusion paints the singers voice well into the musical foreground without grating on the inner ear, giving the track a fresh and vibrant sound as Kennedy unloads. This is one of my favourite tracks, and the Fusion does it full justice here.

Timbre is definitely on the cooler and more analytical side, with the slight warmth coming up from the bass not really doing too much to colour the delivery above. Piano is rendered fairly accurately, just lacking that last hint of warmth to give it a truly organic tone, and sitting a little behind the guitar and other midrange instrumentation on the stage. The Fusion is a monitor that is content to stay away from too much colour in the midrange, so while it captures the dynamic shifts of a song very well (the mythical PRaT), it gives a fairly straight-laced rendition rather than overdosing on emotional engagement.


If you read one section of this review, this is the one I’d recommend, as this is definitely where the magic happens for this particular IEM. The Fusion utilises the new magnetostatic driver from EarBridge to handle the high end. This aims to provide the benefits of a traditional electrostatic driver, but utilising permanent magnets in place of more conventional high voltage static electricity. It achieves this by suspending the diaphragm between a symmetrical pair of magnets, removing the need for ultra high voltage or any bulky transformers to power it.

So far, so techie – so how does it sound? Honestly, the Fusion sounds unlike any other IEM I’ve heard in the higher frequencies. It’s undeniably bright, but it achieves this without harshness or brittleness. It’s not as effortlessly ethereal as the current batch of EST-driven mid-fi or flagship tier models out there using the now-ubiquitous Sonion first and second-gen EST drivers, with a more weighted and traditionally “crisp” tone that is more normally associated with a good balanced armature driver. Unlike an all-BA setup, the magnetostatic has a more natural timbre and a more physical sense of weight to the sound, combining the best elements of both a BA and DD type signature to give something in the high end that is blisteringly fast and punchy at the same time, while packing in more detail than either type usually achieves. Correctly implemented (which is the key to all good IEMs), I genuinely think that the magnetostatic tweeter Itsfit have licensed here is the future of “tri-brid” setups rather than the more popular EST option. It’s just THAT good.

So, enough hyperbole – let’s get down to some music. Revisiting “Starlight” by Slash, the harmonic-heavy guitar intro sounding raw and biting. The Fusion doesn’t take any edge off here, with the wailing guitar sounding full but not painful or harsh in the ear. Similarly with Myles Kennedy’s rasping falsetto, the Fusion manages to keep the edge in his delivery without shredding the listener’s eardrums in the process. It’s a thick, full sort of treble, but as stated above, this is still an undeniably bright sort of sound. There is a crispness and a crunch to the leading edge of notes, the speed of the magnetostatic driver making short work of complex passages like “Eruption” by the late, great Eddie Van Halen. The driver captures the blistering speed of Van Halen’s pickings and the double-tapped harmonics without blurring any of the transients (the short bursts of energy you hear at the start of any sound), keeping everything tight and controlled as the notes rain down on the listener.

Cymbals sound particularly realistic for me on the Fusion, capturing both the metallic zing and a natural sense of decay as the splashes subside, again without any blurring or smearing in busier tracks. “Spirits, Ghosts and Outlaws” by Joe Satriani starts with a deliberately emphasised cymbal pattern, and the Fusion handles it superbly, painting each strike vividly in the ear. You can almost feel the drumstick hits as the track progresses, the sharp zing sitting above Satriani’s distorted guitar in the mix and demanding as much attention as the actual guitar lines themselves as the track chugs on.

This brings me to a potential downside of the Fusion: if you are treble sensitive or prefer a darker tuning, this may not be the IEM for you. I’m typically a fan of a warmer and darker sort of tone with my in-ear gear and the Fusion is probably just on the edge of what I’m happy with in terms of brightness and emphasis. The treble is pushed forwards in the mix, so plays a prominent role in proceedings on pretty much every track you listen to. For some music, that extra emphasis and sizzle can be a little addictive, but if you’re sensitive to a more prominent high-end, then you probably want to demo these beauties before jumping onboard the Itsfit wagon.

Throwing some Chemical Brothers into the mix, the Fusion handles the scratchy “Saturate” and the more upbeat “The Salmon Dance” from their album We Are The Night equally well. The scratchy beats and driving bass are peppered with fine details floating around the top of the sound, synth lines wavering and wobbling in and out of the soundscape and surrounding the listener. There is plenty of detail hidden in these tracks, and the Fusion picks up on the finer texture and nuance very well, easily posting a TOTL-worthy sense of resolution.

Switching to some classical, “Flight Of The Bumblebee” by virtuoso violinist David Garrett is a fizzing buzzbomb of a track, the Fusion capturing each bow stroke and finger pluck in high resolution without getting confused or becoming congested. It’s a veritable blur of a track coming in at under 80 seconds from start to finish, and the Fusion dances through the track without putting a step wrong. As mentioned, you feel you can almost picture the finger placement on the neck of the violin in some parts – this isn’t the most resolving IEM I’ve ever heard (even in the treble), but it’s certainly no slouch when it comes to digging detail out of the high frequencies in a recording.

Overall, the Fusion presents treble that is crisp, crunchy and undeniably bright, sitting in front of the midrange but in line with the bass in the signature. It’s weighty but extremely fast, and gives the music a sense of energy that is addictive on some tracks. It’s not a tuning for those shy of frequencies north of 4KHz, but if you are a fan of some crisp and detailed high end, the new driver technology presents music in a way I haven’t heard before, combing the best aspects of the more traditional BA or DD approach with some of the technical strengths of the newer Sonion ESTs to provide something truly special. This is top tier treble.

Power requirements and synergy

At 98 dB/mW and 13.1 Ohms, the Fusion shouldn’t be a particularly hard IEM to drive on paper, and that holds pretty true in practice. It can be satisfactorily driven to a louder than comfortable volume by the Sony NW-A55 (a DAP not known for its beefy output) at 60/120 volume steps in low gain. Given that the Sony can only muster 35mW at optimum output, as long as you don’t have a source that is thinner than an anorexic’s dessert menu then you should be just fine.

In terms of driveability, the Fusion doesn’t seem to benefit from additional wattage or current either, with the drivers exhibiting no notable gains when powered from something with a more muscular output level. The DD and magnetostatic drivers will certainly take advantage of any extra fidelity they can find in the audio chain, but extra juice doesn’t seem to be a necessity to get this IEM to sing.

Given that the Fusion is naturally bright, I would suggest pairings with more organic or warm sources will work best. It sounds OK with the Cayin N6ii/E02 setup I currently have as my “high end” DAP rig, but sounds much more engaging with the N6ii’s little brother the Cayin N3 Pro – the ultra-linear tube output gives the treble and bass a richness that really suits the Fusion signature. As mentioned, even the A55 sounds good with these (especially with the MrWalkman firmware mod). If you pair the Fusion with something harsh or low quality it won’t hide the flaws, but for most decent audiophile gear this should be a pretty good matchup.

Tip choice

Like the DAP section above, I would recommend something that doesn’t exacerbate the already bright leanings of this hybrid. Silicon tips are a bit of a mixed bag for me – JVC Spiral Dots are OK but nothing special (which is unusual in itself for the jack of all trades of the audio tip world). Flare Audio wide bore tips (both silicon and foam) are a definite no-no, making the sound a tad TOO bright and crispy for my ears. Ditto for Spinfit, which wasn’t a brilliant pairing for my preferences.

My favourite tips for these IEMs are all definitely foam-based. Comply add a good weight to the bass and take some of the spice out of the top end, but can end up neutering some of what makes the Fusion so unique, so I have settled on the Mandarine orange foam tips, which do a good job of adding heft to the low end without losing any of the zip from higher up the frequency range. Ditto for my trust Campfire Audio marshmallow foamies, but I personally find the Mandarines a little more solid for this particular IEM. The Flare Audio audiophile foamies get an honourable mention, but the horn shaped and ultra wide bore can again emphasise the top end a little too much in the presentation for my preferences.

Soundstage, separation and layering

The Fusion has a large stage, pushing out from the imaginary confines of the listener’s head by a few cm laterally. The Itsfit IEM also exhibits good height, giving an image that is almost as tall as it is broad. Depth is decent but not remarkable, painting the sonic picture as more of an oval rather than a sphere. Note size is on the larger size, so coupled with a neutral to slightly forward sounding presentation, it gives the impression of a big sound.

Imaging is where this IEM truly shines, the tri-brid setup used by Itsfit placing each instrument and vocal in an exact point on the stage.


Campfire Audio Solaris 2020 – (Hybrid 1xDD 3xBA, c. $1499)

The Solaris is the current hybrid flagship from the Portland based audio manufacturer Campfire Audio, who should be more than familiar to anyone with a passing interest in the current high end IEM scene. It sports a similar number of drivers in a hybrid configuration, but pairs two balanced armatures firing into a 3D-printed tuning chamber for the treble, a vented BA for the midrange and a 10mm diamond-coated dynamic driver for the low end.

Starting with the stage, the presentation is not as wide on the Solaris, but feels appreciably deeper. The Fusion throws its notes out further along the X-axis, but feels more oval in terms of stage depth compared to the more spherical Campfire model.

Tonality wise, the Solaris 2020 feels more analogue, with a warmer and more musical approach compared to the crisp sharpness of the Itsfit. The Fusion is definitely the brighter of the two IEMs here, with a presentation that leans a lot more towards a colder U-shape in comparison to the Solaris’ warmer W.

Sub bass is more emphasised on the Fusion, with an additional few dB adding weight to the underneath of basslines and giving an almost club like thump down low compared to the more reserved CA model. Mid bass quantity is roughly similar on both, sounding comparatively leaner on the Fusion due to the bigger sub emphasis. Quality is similar on both IEMs, with the Solaris 2020’s ADLC driver just edging ahead in terms of resolution and texture, but not by a huge amount. Both IEMs can produce good levels of texture and resolution, and can confidently be considered top tier in terms of raw performance.

Moving up the frequencies, the midrange is similar in emphasis, but positioned a shade further back on the Fusion. The Itsfit model also sounds thinner and more aggressive than the Solaris here despite using two armatures to the 2020’s one, lacking the final dash of raw detail and finesse the the Solaris possesses. While the mids on the Fusion are fairly accomplished, it doesn’t quite match the more emotional and revealing Solaris here. For fans of a thinner and sharper sound the Fusion will probably better suit those preferences, but just can’t quite match the overall quality of the Solaris. For people looking for a warmer or more emotional delivery in the midrange, the Solaris is an easy recommendation here.

Treble is quite different between the two IEMs, with the Fusion carrying a significantly brighter top end than the Solaris. In comparison, the Solaris highs are slightly more substantial but more laid back. They sound smoother and less aggressive with cymbal crashes and other percussion, and provide a greater sense of airiness compared to the more aggressive and vivid Fusion presentation. Quality wise it’s a draw, with both setups being fairly evenly matched in terms of resolution and clarity.

If you like your highs bright, sharp and plentiful, the Fusion will be the suggestion here. If you prefer a top end that is still sparkly but a little softer and smoother, the Solaris wins out. The 2020 is also by far the more forgiving of the two IEMs for badly mastered or hot recordings as a direct result, which is something to bear in mind if your music collection consists mainly of recordings of glass being broken in a chalkboard nailfile testing facility.

With regards to technicalities, the imaging on the Fusion easily keeps pace with the Solaris, which can be considered top tier in this aspect. Separation in the lows and highs is slightly better on the Fusion, but the midrange feels sightly more cluttered in direct comparison to the Campfire model. Resolution overall is taken by the Solaris, with the additional clarity in the midrange and a slightly tighter presentation in the bass sealing the deal there.

Packaging and accessories are a tie, with the Campfire model coming with a better stock cable but a slightly less impressive case. Both IEMs come with decent accessories, but the Solaris just edges ahead with choice of tips.

These are two fairly well matched IEMs – the Fusion is a brighter and more aggressive sounding monitor, but still manages to compete fairly well with the more expensive Campfire flagship in a lot of areas. I love the sound of the Fusion, but I think the Solaris is the better IEM overall, pulling ahead in a few key areas and presenting a more balanced and musically enthralling sound to the listener.

IMR Acoustics Opus Mia – (Hybrid 1xDD, 2xEST, 1x piezo, c. £600)

The Opus Mia is one of the 2020 releases from prolific IEM tinkerers IMR Acoustics, sporting a single 15mm beryllium coated dynamic driver, dual Sonion electrostatic drivers for the mid and high ranges and a ceramic piezo tweeter. They are a filter-based IEM, allowing more than 40 different tuning configurations between the openable back vent and two part nozzle filters.

Packaging is pretty different between the two; the IMR model comes in a medium sized portable hard case (complete with carry handle), with all the accessories set in foam inserts inside. There is no “unboxing” as such – you just unzip the case and get straight to the goods. In that aspect, the Itsfit definitely come across as the more refined of the two, although for accessories IMR are difficult to beat at any price, with the Opus Mia being bundled with two decent quality cables (balanced and unbalanced), multiple different sets of ear tips, the filter sections set in their own metal carrying bars and even a 6.3mm adapter to hook them up to a headphone amp.

Sound-wise, both models are very different. The Opus Mia is something of a chameleon with its multiple tuning options, but with most filters there is no getting away from the fact this is a bassy sounding in-ear. The 15mm beryllium coated DD does its job well here, shifting large volumes of air into the inner ear and providing bass that goes from thick and punchy on the “lighter’ filters to positively tooth-rattling on the basshead settings. It isn’t just one-note bass either, competing on the same technical level as the Fusion in terms of tightness and texture, and actually outdoing it in some aspects. Simply put, if you like bass, the Opus Mia will provide more of it at the same or higher quality as the Fusion. On the other hand, if you prefer a less overtly “musical” or bass-heavy tuning, the Fusion is the obvious choice here.

Moving into the mids, and the Opus Mia presents a midrange that is thicker and considerably more forward than the Fusion. There is a hint of vividness to the IMR that borders on sharpness in some ranges. It provides good levels of detail on the less bassy filters thanks to the dual ESTs, but the finer nuances of a track can be drowned out a little if you go full basshead. Overall, for thickness and tone I prefer the OM here, so if you don’t have an issue with a sightly pushed high mid/low treble region, the IMR is the more musical and emotive for my preferences.

Treble is not dissimilar, but feels more prominent on the Fusion. The magnetostatic drivers give a slightly crisper and zingier sound, compared to the thicker and smoother Opus Mia. Detail wise the Fusion probably edges things, but the Opus Mia isn’t found too wanting, with the dual ESTs and ceramic piezo driver providing a decent level of resolution.

Staging-wise, the IMR model throws it a stage that is bigger than the Fusion in all directions, presenting a sonic image that is grander and larger in area than the Itsfit, even with the vents closed. Separation is surprisingly good on the IMR considering the tuning, but the Fusion is the more adept of the two in this regard. Imaging is good on both, but just slightly more pinpoint on the Fusion.

Overall, the Opus Mia provides a much thicker, bassier take on things with more emphasis on a musical tuning rather than resolution or clarity, so will appeal to a different section of the market. Technically the two models aren’t actually a million miles apart, so it will be down to preference and staging to determine which IEM you prefer. For me personally, the OM probably shades it in my personal preferences due to the bigger staging and more powerful and engaging sound, along with the ability to tweak the tuning using the various filter options.

Unique Melody MEST – (Hybrid 1xDD, 4xBA, 2xEST, 1xBone Conduction, c. $1400)

The MEST is a 2020 release from Chinese IEM giant Unique Melody, and has to rank as one of the most intriguing releases into the IEM space for the last year or two. Not content with surfing the current wave of “tri-brid” releases flooding the flagship market from the big name IEM houses, UM decided to go one better and release a “quad-brid” setup, taking the now common DD/BA/EST design and strapping an additional bone conduction driver to the design (or more correctly, to the carbon fibre faceplate).

In terms of physical dimensions and shell design, both in-ears are pretty similar. The MEST shares a similar physical thickness, being slightly smoother on the inner face and less contoured, and having a slightly longer nozzle. Neither are small, but comfort is roughly equal, with the Fusion just shading it for security of fit as it hugs the contours of the ear slightly better. Looks-wise it’s a draw as well, with the understated but classy looking blue and black carbon fibre shells of the MEST holding up well against the more “custom” design of the Fusion.

In terms of packaging, the Itsfit feels slightly more luxurious, with a much more satisfying unboxing experience and presentation. In terms of actual accessories it’s a draw, with the MEST providing a slightly thicker and more high quality cable than the Fusion and a custom carry case from the Korean manufacturer Dignis in blue and black. It’s less pocketable than the Itsfit puck, but slightly more convenient, with dividers to keep the IEM shells apart and enough space for a decent amount of accessories as well.

Sound wise these two IEMs are not that similar, with the MEST having a more W-shaped compared to the more traditional V/U of the Fusion. The UM present a more vivid and up front sound, pushing the midrange considerably more forward than the comparatively laid back Fusion. While the Fusion certainly isn’t lacking energy, the MEST comes across as a more engaging and lively listen, demanding a more active participation from the user than the Itsfit model.

The soundstage feels more immersive and three-dimensional on the MEST, with a similar width but a more defined sense of placement along the Z-axis, putting instruments more perceptibly in front or behind the listener. The MEST also sets the listener a little closer to the imaginary stage than the Fusion, giving a more “front row” style of presentation in comparison. The MEST presents a bigger sonic “picture” in the ear, with the instruments feeling larger and closer to the listener compared to the more distant Itsfit. Layering and separation are comparable between the pair, with the MEST again just edging ahead technically. Imaging is a draw, with both IEMs offering razor sharp placement of instruments and musicians across the virtual stage.

Bass levels are fairly similar in quantity – to me, the MEST feels the fuller of the two, hitting with more physical power and slam than the Fusion, and having a slightly more prominent mid-bass. There is an additional element of “physicality” that the MEST seems to impart to the low end that leaves the Fusion a little behind in terms of texture. The MEST also seems a hair quicker in the bass, with the Fusion sporting a slower decay and more “traditional” DD type sound in comparison.

The mids are very different in style, with the neutral presentation of the Fusion contrasting with the much more forward and emphasised tuning used by the MEST. The mids on the MEST feel thicker and more energetic, but also technically stronger. The detail and resolution is more apparent on the UM model, presenting a bigger sonic image with more clarity and texture, lending the usual midrange instrumentation like guitar and piano a much more substantial feel. Tracks like “World On Fire” by Slash positively drip with aggression and emotion, in contrast to the more neutral and reserved Itsfit. This is the one area where the MEST pulls definitively clear of the Fusion, unless you prefer a more recessed and solemn midrange.

Moving up to the treble, the contest is far closer. The MEST packs in a dual Sonion EST driver array alongside its unique bone conduction driver, which provides a crisp and airy treble that is high on detail but avoids harshness. The magnetostatic driver in the Fusion excels in the upper end, but the MEST configuration is equally excellent. Technically both are similar, with the MEST config just shading it in terms of resolution and clarity, but not by much. In terms of energy, the Fusion actually out-performs the MEST for me, providing more fizz in the inner ear than the comparatively more understated Unique Melody model. Neither IEM are prone to harshness, but the Fusion is definitely the brighter and more aggressive sounding of the two monitors. In terms of air, the MEST feels more airy, but the treble is slightly further back in the stage than the Fusion, so the notes feel lighter and less substantial in the ear. This is more to do with preference than execution in terms of which is better, as both are top tier performers in this aspect.

Overall, these IEMs are both very good for the price, but even given the additional $450-odd in price between the two, the jump in SQ is slightly more pronounced on the MEST, which just edges it in multiple areas to provide a sound that is both more technical and more engaging at the same time. If you prefer a brighter sound or a more laid back midrange then the Fusion may be more up your street, but for most people the MEST are likely to be the more enjoyable choice, unless cost is a barrier.


The Fusion from Itsfit is an unusual sounding IEM, treading a different path to a lot of the current market tunings in its price bracket. It is unashamedly bright and zippy, but not shy of offering a decent bass foundation to the sound either. It is a beautifully made and designed piece, with thoughtful accessories and a real feeling of quality throughout. For the price, it’s both a technical and musical achievement.

As with all things, there is usually a but… in the case of the Fusion, it is the midrange. While the mids technically do nothing wrong, compared to the excellence of the bass and treble areas, they are just a little soulless and lacking in the engagement factor needed to really push this IEM to the next level. As stated in the review, they are detailed and of decent quality, but for my preferences, they are the one area that Itsfit could improve on to make this already impressive IEM pretty much untouchable at its price point.

If you love crispy, beautiful treble and favour a leaner or more analytical tone, these IEMs are probably perfect for you. For everyone else, they are still a very entertaining and accomplished tuning – if this is what the team can achieve with their second ever model, I am very much looking forward to seeing where they can take their “house sound” in future.

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