Nuclear Physics:
A review of the Itsfit Fusion IEM.
Introduction:
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:
https://itsfitlab.com/fusion/
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.
Photos:
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
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
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
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!
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
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
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”
Conclusion:
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
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
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.
