Custom Art Ei.3: Finest sound from a fresh Polish Company - [Review] 🇬🇧


Hierbei handelt es sich um meine englischsprachige Version meines Custom Art Ei.3 Reviews, das in deutscher Form hier gefunden werden kann:


If you have a hobby that isn’t just a hobby for you but a real passion that means a lot to you, you will probably eventually turn into an expert in this field over time.
For Piotr Granicki, everything started with a high passion for music and in-ears. Over time, this evolved into the hobby of designing and building custom-moulded in-ear monitors (also referred to as “CIEMs”) which requires good mathematical skills (for calculating the resistor and capacitor size of the crossover and tubing length plus diameter as well as value of the acoustic damper elements for the desired sound), dexterity (for making the moulds based on the ear impressions and then for crafting the in-ears) and more.
Piotr has managed to achieve what some people want to but often don’t dare to do – he turned his passion and hobby into a successful business, Custom Art, and is now building custom-moulded in-ear monitors for a living, and is doing it really well, based on feedback from customers and reviewers (not much surprisingly as he has got everything that is needed – the passion, the knowledge and the gear).

The Ei.3 ( was Custom Art’s first acrylic-only CIEM – all of their previous creations were built with silicone that takes more time to build and is more expensive and difficult to deal with in the end. The Ei.3 is meant as an engaging but still natural sounding, affordable CIEM with a powerful bass, starting from less than €300 (€275 outside of the EU, €340 inside) with a basic colour scheme and finish.
The Custom Art products were already really reasonably priced for hand-crafted CIEMs compared to other big brand companies’ products that have distributors in the EU, but with the Ei.3, they introduced an in-ear with three drivers and three acoustic ways, probably making it the world’s most affordable three-way BA-only CIEM on the market.

If you are like me and prefer the fit and handling of universal fit in-ears over CIEMs, you can also kindly ask Custom Art and they might make an exception and build a UIEM for you. There is no guarantee that the sound will be identical, but it might be extremely close/similar if your ear anatomy is very UIEM-friendly (when I got my UERM CIEMs, I could compare them to the universal demo model and the sound was extremely similar so that I really wished back then that they were also available as UIEMs).

Before I go on with my review, I want to take the time to personally thank Piotr and Custom Art for sending me a sample of the Ei.3 (on request built universal fit housings) free of charge in exchange for an honest, unbiased review and comparison.

Technical Specifications:

Price (depending on colours and designs; starting from): PLN1359/€340 inside the EU, PLN1100/€275 outside of the EU
Drivers: 3x BA per side
Acoustic Ways: 3 (1x back-vented woofer, 1x full-range, 1x tweeter)
Sensitivity: 118 dB @ 1 kHz @ 0.1 V
Impedance: 48 Ohms @ 1 kHz
Tonal Range: 10 Hz – 17 kHz (+/- 20 dB into an IEC 711 coupler)

Delivery Content:

Just like the CIEM variant, the universal Ei.3 arrived in a Peli 1010 case with transparent lid (I would personally prefer a solid lid with inner padding and a Custom Art logo on the outside), containing the in-ears, a cleaning tool as well as a drying capsule and a warranty card that also contains other interesting information. As a universal model, mine came also with a selection of different ear tips.

Looks, Feels, Build Quality:

I don’t want to go too much into detail here, mainly because with the custom-moulded in-ear, you have a plethora of different colours and designs to choose from, along with different faceplates and finishes (as with all CIEM manufacturers, some are included in the base price whereas some cost an upcharge). Custom artworks, pictures and texts are possible, too.

If anyone is wondering, the design I got is metallic amber-coloured bodies with metallic black faceplates and golden negative Custom Art logos. On the inside of the bodies, coloured serial numbers in red and blue to match the correct sides can be found. The Ei.3 has got a dual-bore design with a larger and a smaller sound outlet at the end of the nozzle.
The build quality of the acrylic bodies is excellent and the faceplates are connected seamlessly to the bodies.

The twisted/braided black cable consists of three strands below the y-split, has got a transparent chin-slider above it and has got good strain relief on every single transition. It is actually a quite commonly used and reliable cable for CIEMs and many higher-end UIEMs.

Comfort, Isolation:

Here I don’t want to go too much into detail, because the fit of a universal demo/universal model will greatly depend on one’s individual ear anatomy, and because the fit and comfort of the custom-moulded in-ear will highly depend on the quality of the ear impressions that reach the lab (so best be sure to let a good and experienced audiologist take the ear impressions if you decide to go for any CIEM, and best bring along the instructions on how to properly take the ear impressions that most CIEM manufacturers have to download on their website).

The universal version has got an excellent fit in my ears and seals easily. I would personally also definitely encourage Custom Art to also offer universal fit versions by default on their website.

Due to the closed acrylic bodies, isolation is logically really high.


My main sources for listening were my iBasso DX90, my Chord Mojo + Leckerton UHA-6S.MKII stack, the Cowon Plenue M2 as well as the LH Labs Geek Out IEM 100.

I used the largest silicone tips that were provided with the universal fit version for listening and testing.

Side-note: Although this was not the case with my UERM CIEM and its universal fit demo version, it might of course be that my impressions of the universal fit Ei.3 might be different from its custom-moulded version to some degree.


The sound description on the Custom Art website is very fitting in my opinion, which is actually not that much surprising, considering Piotr’s/Custom Art’s background and transparency.

What you will get is an emphasised but not overwhelming bass that appears to be strong but doesn’t bleed into the mids and also never sounds overpowered or out of place. It is definitely not a basshead in-ear and it doesn’t even have that much overall quantity but just enough to add some fun to the music – the majority of in-ears with a dynamic driver for the lows is bassier, and the same goes (to a lesser degree) for some of the bassier BA-only in-ears – if the track doesn’t have a deep-reaching bass on it, the Ei.3 won’t add anything unnecessary.
Just as the description says, the Ei.3 has got a great balance between accuracy and engagement.
The bass digs deep into the sub-bass and comes along with a powerful slam in the midbass and upper bass, along with some warmth in the root that doesn’t colour the midrange.
The midrange and vocal range sounds natural, realistic and uncoloured. It is overall quite spot-on uncoloured to my ears.
The treble sounds overall smooth and even without any offensiveness except for a slight clarity lift in the upper highs that is however not harsh sounding either.

Going more into detail listening to sine sweeps, I hear the lows to start slowly and evenly climbing around 600 Hz, then reaching their climax around 100 Hz. It can be kept upright in the midbass and sub-bass and only ever so slightly loses quantity below 35 Hz. My ears tell me that quantity-wise, the lows are a bit more than 7 dB more present compared to a diffuse-field flat in-ear, which is what some people would still consider balanced – just as mentioned, the bass is anything than overdone.
Between 1.5 and 3 kHz, I hear the level to be very slightly in the background, but it comes back right after. I can spot an emphasis between 7.1 and 8.5 kHz. The super treble above 10 kHz is then slowly losing quantity (there is not as much subtle glare and extension above 10 kHz as with some other in-ears, however the extension is still good).

I hear the sound as being overall very coherent and with a good balance between fun and accuracy. It is not neutral but also not too sounded and everything sounds realistic – there is nothing that sounds out of place and instruments sound realistic. Chris-approved.


Not always but very often, in-ears with three acoustic ways have shown to sound somewhat more resolving in the midrange than in-ears with only two acoustic ways – I remember when I imported my Audio Technica ATH-IM03 from Japan, I initially thought that it was a triple-driver in-ear with two acoustic ways (2x lows, 1x mids/highs configuration) based on what I had read so far. When I first listened to it, I thought “hmmm, to me the midrange sounds somewhat more detailed than with most two-way in-ears and has got that extra resolution and different ‘character’” – this “character” is more what you feel subliminally and is nothing that I could really put into words. Anyway, what I assumed to know and what I heard did not match, so I did some additional research and found out that the ATH-IM03 actually had three acoustic ways, so what I had just got to know finally matched with what I heard.

The Custom Art Ei.3, this I can already say, is quite a bit better for its price than I expected it to be, based on hearing some other entry-level CIEM demos (I am mainly referring to the UE4 Pro when saying this).

The Ei.3 doesn’t have the hardest/tightest BA-sound but takes a less aggressive bottom-end approach that is however extremely nicely made – its bass is fast but not as fast as with a few other BA-based in-ears (if I had to put it into numbers, I would say it has about 70% absolute speed, while 7 is ironically the number that is stated on the Custom Art website in the “bass quality” section), yet it has got great quality. What I find really tempting, addictive and extremely well-made about the Ei.3’s bottom-end is that its attack is a little bit on the softer side to give a really gorgeous and visceral bass and sub-bass, however it decays quickly and doesn’t leave any bloom or softness. Yes, it is quick, clean and detailed down low, which is also why I personally and subjectively prefer the “character” of a Balanced Armature bass over the one of a dynamic driver (with just very few exceptions regarding some single-BA in-ears). And what I also find excellent about the Ei.3’s lower end is that while the BA driver dedicated for it is vented, it doesn’t sound too slow or soft which I think is sometimes the case with the InEar StageDiver SD-2 and Fischer Amps FA-4E XB (as opposed to the regular FA-3E that is also using two back-vented woofers but sounds arid/tight, clean and quick).

Despite the description on the website of being “the best pick for EDM or [R]ap genres”, the Ei.3 doesn’t fall short in the vocal range at all – voices sound detailed and the in-ear’s speech intelligibility is high. The Ei.3 is also perfectly suited for someone who probably mainly listens to vocal music but doesn’t want the midrange to be forward or have a favour for either male or female vocals.

While the treble doesn’t lack details, it lacks the last bit of openness or separation and sounds a bit congested, but what the hell, the Ei.3 is an extremely fair priced and very affordable custom-moulded in-ear that sounds great overall and has got a really nice soundstage (I will get to this in a moment in a separate part of my review), and I can really tell you that I don’t believe that there are that many (or any?) other CIEMs at this price point that a) offer the same technology + quality or b) are on the same technical level – for example, Ultimate Ears’ most affordable CIEM, the UE4 Pro, does not only cost more than the Ei.3, but is also inferior when it comes to precision and details.

What I have briefly read about the Ei.3 in terms of other peoples’ impressions is definitely no lie – it is a well-built CIEM with an outstanding price-performance ratio.


To my ears, the Ei.3’s soundstage sounds quite open, three-dimensional and what could be considered “holographic”. Expansion to the sides is a little wider than where my ears are positioned, and there is really good spatial depth and height, although I would say that the stage is somewhat wider than deep.
The layering and depth sound believable, which is something where many Balanced Armature-based in-ears fall short in this price range, however the Ei.3 doesn’t.

The positioning of instruments is good and precise. The separation is good but not perfect – instruments don’t bleed into each other by any bit but aren’t as focused sounding when playing busy tracks as with some higher-priced in-ears either, however I have a hard time thinking of a lower priced multi-BA in-ear that noticeably surpasses the Custom Art in terms of absolute spatial precision or comes even close (the Pai Audio MR3 is the only model that comes into my mind here).

So yeah, I honestly think that the soundstage is great – it sounds very three-dimensional with very good layering and an excellent reproduction of spatial depth and height. This is, to my experience, quite rarely found in a BA-based in-ear in this price range.
The very convincing and three-dimensional soundstage of the Ei.3 was actually also one of its attributes that lead to a very big grin (that actually really stayed there for a few hours) after I first listened to it, as I really hadn’t expected this level of resolution and imaging already at this price for a CIEM. Even the soundstage alone justifies the price (in my opinion).


In Comparison with other In-Ears:

Noble Audio SAVANNA:
The SAVANNA is a pretty neutral in-ear. Compared to the Ei.3, it has got less bass but also a bit of a roll-off towards the sub-bass, and no peak in the upper treble but an even and flat/neutral upper end.
I would say that the Noble has got the more detailed midrange and treble, and while the SAVANNA has got the slightly faster bass attack and the Ei.3 the slightly faster decay.
Both in-ears have got a convincing and three-dimensional soundstage while the Noble has got the somewhat cleaner separation between single instruments and slightly larger spatiality.

Fischer Amps FA-4E XB:
The Fischer Amps has got the somewhat more present bass and root that unfortunately also bleeds into the midrange, making voices sound full and somewhat dark. In the upper treble, it is the brighter in-ear out of the two and accentuates cymbals more.
I would say that both are about comparably resolving in the midrange. The FA-4E XB sounds somewhat better separated in the treble, however the Ei.3 has got the somewhat less soft and faster bottom-end that also sounds more detailed to me.
While the FA-4E XB has got a really solid soundstage, it always fell short compared to some other in-ears in its price range that are really good in this regard (e.g. the SD-2 or ATH-IM03). The Ei.3’s soundstage is larger to my ears and has also got the more precise placement and separation.

iBasso IT03:
This is going to be interesting – a hybrid in-ear with a fast dynamic bass vs. a multi-BA in-ear with a bottom-end that heads a little into a more dynamic direction.
The IT03 has got slightly less presence in the upper bass but a bit more in the sub-bass, slightly making it more a sub-bass focussed in-ear. The iBasso has got the brighter midrange that still sounds balanced but has got the somewhat greater preference for highlighting female vocals. It is also a little brighter around 5 kHz.
When it comes to the bass character, both in-ears are surprisingly close together. The Ei.3 however has got the faster decay, making it the overall more arid/tight appearing in-ear in the bass. In terms of resolution, I would say that the Ei.3 has got the somewhat more detailed lows whereas the IT03’s treble is a bit better separated. I see both as being comparably resolving in the mids.
The IT03’s soundstage appears a little less deep but a bit wider in comparison and also seems to have the somewhat cleaner separation.

DUNU DN-2002:
The DUNU has got slightly less bass but the fuller lower vocals, making it the somewhat warmer in-ear in comparison. Its vocal range sounds a bit warmer than the Custom Art’s but isn’t really coloured. In the middle highs around 5 kHz, the DUNU is more laid-back.
Directly comparing both, the DUNU has got the more impactful and softer appearing bass, which is not much of a surprise though given that it is a multi-BA vs. Hybrid IEM comparison. I would say that both are on the same technical level in the mids and that the DUNU is slightly better separated in the highs.
The Ei.3’s soundstage appears a bit wider while both seem to have identical depth to my ears. The Custom Art’s soundstage is slightly better separated to my ears.

Audio Technica ATH-IM03:
Important thing to note: I am driving the ATH-IM03 from a very low impedance output and using the stock silicone tips that will sound sometimes more and sometimes less different (with the original tips, the in-ear sounds brighter in the highs, making the sound rather v-shaped) to about all third-party tips that I’ve tried.
The in Europe very hard to obtain (I had to import mine from Japan) and despite my large ears oddly fitting ATH-IM03 has got a tonality that is relatively close to the Ei.3 with just very slightly more bass, the very slightly more distant mids in comparison and a comparable treble.
The Audio Technica however takes everything to a slightly higher technical level, having the tighter bass, somewhat more detailed midrange and also better separated and differentiated treble.
In terms of soundstage, the ATH-IM03 appears to be comparable in terms of dimensions but features the more precise spatial cues with the sharper instrument placement and separation.

Ultimate Ears Triple.Fi 10:
The Triple.Fi 10 is a more v-shaped in-ear with a more distant and slightly hollow and thin appearing midrange. Its treble is brighter and splashier than the Ei.3’s and its bass is also very slightly more present.
Talking tech, I find that the Ei.3 is the technically somewhat more advanced in-ear out of the two. While the Triple.Fi 10’s bass is a bit faster in terms of attack and slightly tighter in comparison, the Ei.3 seems to be more resolving in the lows as well as mids and has got comparable separation in the highs.
I never heard the Triple.Fi 10 as having a three-dimensional soundstage but always found it flat, rather wide and oval. The Ei.3 has got more spatial depth and the better layering while the UE’s stage is a little wider. Both are comparable in terms of instrument separation.


Besides the great craftsmanship you get with it, the sound quality of the Ei.3 is really good, too. It offers a visceral bass that is present but not remotely overwhelming or overdone (it is actually not even far from being balanced) and also doesn’t bleed into the midrange, yet gives you enough quantity to enjoy some good bottom-end rumble and impact. Furthermore, its detail retrieval is very good for the price and the soundstage is rather large and especially nicely textured, layered, three-dimensional and authentic sounding.
So what do you get? An engaging sounding and still not too much sounded in-ear with great value and a three-dimensional and convincing soundstage for a good price.

The thing left to desire is the last bit of separation in the highs and on the soundstage with busy tracks. Is this a turn-off? Definitely not! How much was the price again? Around $300? This, in all honesty, is quite a bargain for the total package (and here I am not even taking into account that the Ei.3 in-ears are actually CIEMs which take more effort to make and are therefore usually more expensive than similarly performing UIEMs – with the Ei.3 however, you get a great sounding acrylic CIEM for a very affordable price without any real CIEM competition).

My rating is 95.55% overall (with my usual 70% sound/value (94.5) and 30% build quality/fit/comfort (98) weighting) – yes, it can be assumed that I think that it is an excellent in-ear for an excellent price, and that I also personally quite love it (I think the Ei.3 will be my go-to in-ear for outside listening for a bassy but not bass-heavy in-ear with a precise sound along with a convincing soundstage).