PENON SERIAL Review: Master of Musicality

-Bass presence, layering and fullness
-Mids presence, layering and fullness
-Natural dense timbre
-beautifuly balanced warm W shape tonality
-wide lush male and female vocal
-thick yet well articulated layering
-good enough transparency
-smooth non fatiguing
-heavy note weight and dynamic
-wide holographic soundstage
-excellent all arounder
-dark treble that doesnt lack in details and nuance
-excellent accessories
-good construction with appealing look
-great price value

-not the cleanest sound
-not the sharpest resolution
-not the most extended and sparkly treble
-not for treble head



Penon is mostly known as an audio distributor and cables maker, yet they begin to release earphones years ago. Their IEM like the Vortex single DD or Globe hybrid DD+2BA have a solid fan base. It seem the Serial I will review today is quite appreciate by audio community too.
Priced 300$ (but on sale right now at 270$), the Serial is a triple dynamic drivers earphone using 10mm biological DD for low, 8mm Titanium DD for mids and 6mm PU DD for highs.
Since i’m quite a fan of Unique Melody 3DT, my curiosity drive me to contact Penon for testing this IEM, so, these doesn’t come out of the blue but are lucid independant decision driven by pure audiophile curiosity.
Now, let see in this review if Penon achieve a cohesive tuning with all these exotic DD and if it worth the price tag too.


Model: Serial
Driver: 3 Dynamic Driver
Impedance: 18 ohm
Sensitivity: 103dB
Frequency response: 20-20kHz
Connector: 2Pin 0.78mm
Plug: 3.5mm audio, 2.5mm balanced, 4.4mm balanced
Cable: 8 shares OCC & silver-plated Mixed Braided
Cable length: 1.2M
18 months warranty



What hit me first seing the Serial is how small they are for triple DD IEM, about 1.5times smaller than UM 3DT for example. After this, it was how beautifull the back colorful stabilized wood panels were, this is arsty craftmanship at it’s best, as I like it. When it come to the shell, its made of medical grade resin plastic, it feel sturdy and it’s very smooth and light too. The organic shape is very compfortable, i don’t feel it as if it were ”part of my body”. Isolation is above average and sound leakage minimal. Nozzle is made of metal and feel durable too. 2pin connector are solidly embeded in shell body. Their no low quality control here, everything feel flagship as we can expect with a 300$ IEM.


Now when it come to packaging, their nothing to say apart the fact i was worry of number of accessories seeing how small the box was. But then, i was overwhelmed by the generous amount of whats include. Don’t judge anything by it’s size! Here we have high quality carrying case, not a basic one, something durable and elegant. We have a cable leather pouch and holder, cleaning brush and clamp cable holder. 6 pairs of good quality ear tips and, just wow, this high end balanced cable.


This cable is the Penon CS819 OCC & Silver-plated Mixed Braided 2.5mm balanced cable and sell for 50$ on their Ali express store. Its well built with sturdy connector. Its smooth and flexible and I appreciate it doN’t have ear hook for more versatile use. It doesn’t drastically affect sound rendering, perhaps add with of warmth and timbre density, yet keeping resolution, transparency and dynamic scaling intact. This might become one of my fav cable in fact. You can choose between 3.5mm single ended or 2.5mm-4.4mm balanced models. Very impressive.

All in all, this is excellent accessories that put to shame lot of pricier IEM. Respect, Penon!



The Serial offer a dark W shape signature, where bass and mids trigger all attention. We can call it bassy L shape too, or even balanced U shape due to sub bass emphasis. Its the type of musicality that is thick as a whole and very cohesive, yet feel open and widely layered. Nothing sound like the Serial, yet when you listen to it you feel at home, it’s weighty in its dynamic yet laid back in treble. But don’t be scare of the dark here, since everything sound full: bass, mids and treble are all meaty with this unique sens of holographic layering, resolution isn’t lacking but highs are soften and don’t have spike in brilliance and air region. Once you enter critical listening mode, the Serial are highly rewarding in details and nuance, but doesn’t force it with fake clarity boost.

Those are for bass lover first, both in quality and quantity, the low end is phenomenal in how fully extracted and layered it felt. These are one of few IEM where i can focus on bass player and see it’s beefy resonant bass line as if I was at it’s side. So we have a hint more sub bass boost but this doesn’t stole slam effect, which have warm weighty punch, but doesn’t magnify kick drum presence and texture, here, it favor the texture of bass instrument from acoustic to electric bass to synth. This aren’t exactly basshead too, since it’s too well balanced and cohesive with rest of spectrum for that, yet, when the cello or bassist go solo in a band, you’ll understand how talented the performance can go, since it dig down to 20hz, offer vibrant well controlled rumble or resonance, have dense body full of natural air and lead attack grip that doesn’t create timbral imbalance. I can’t rave enough about the bass response of these, since it’s a versatile one that can benefit wide range of music from jazz to classical, to electronic to soul to r&b to rap etc. It find the sweet spot balance between sub boost, slight mid bass boost, slight dip in high bass then extra boost in lower mids, chunky is the result and the use of 3 dynamic driver avoid muddiness due to excellent layering capacity. No doubt the Serial would be dream IEM for bassist that wanna monitor their playing in a band, i need to underline again how well its physicality is extracted, it’s presence is not due to texture boost but low harmonic tone boost. The timbre is buttery, colored with hint of liquid warmth and palpable vibrancy. Is it the fastest? I don’t think so, is its ultra clean in separation? Nope, its more about transparent layering and kick drum is dark sounding. So, only music that i would not suggest the Serial is perhaps for very fast rock or jazz fusion that have one or 2 pumped up drummer, so, while it would be god to monitor bassist, the lack of texture and kick drum definition as well as tamed percussion energy will be problematic for drum player.

Since I praise so much the bass, mid range should be underwhelming right? It should take second plan, but this is the magi of Serial, the mid range is as addictive and captivating as the bass, as full, wide and thick in presence too yet with great transparency for proper layering. You know when you can’t wait your singer to begin to sing in a track cause you know it would be so musically rewarding? This is it with the serial, and to my ears it trigger this eargasmic experience both for male and female vocal. What is impressive too, it’s the fact pina gain isn’t too high, so it’s not vocal presence that is forced at you, shot at you with impatient urgency, its blossom widely and bigger than nature projection, its not compressed vocal that are stock in middle of instrument, nor veiled by bass bleed, it unwrap fully and take all the stage in openness, and it’s smooth, lush, dense. Female vocal are free of sibilance, with hint of extra low harmonic emphasis that benefit breathyness and thickness, inflicting even more on emotional response of listener. Madeleine Peyroux sound as wonderful as Timber Timbre. So, to some extend, due to soften upper mids that can affect slightly definition edge of sound envelope of instrument like piano, the Serial favor woodwind instruments and vocal, and let me tell you that saxophone sound freaking marvelous with those, listening to Prism Quartet is intensely beautiful, even if more than on sax play in same range, the layering doesn’t mix up and notes are fulfill with air and color nuance, its smooth yet rich and free of this over textured presentation that affect naturalness of instrument tone as well as can distract us from plain musical pleasure. And for piano, it’s not bad since note weight are felt, resonance is open, yet definition of each note is a bit darken, so the Serial are just not end game for piano lover, yet might be for vocal, sax, trumpet, cello and even violin, since this time, its lush and have hint of texture bit that help attack articulation without going overly abrasive and raspy.

Perhaps I worry you with my introduction to treble, that i call slightly dark but be reassure, it’s not overly so and very rich and full sounding, here it’s well balanced and cohesive, the Serial don’t want you to know their 3 different dynamic drivers hide in its body by overly emphasizing texture variance of their drivers diaphragm. So, we have a smooth, natural sounding treble with just a hint of extra snap so snare and brilliant percussion can have enough sens of energy. The details are there, but not in front of bass and mids, which tend to hook the attention more, as it should be unless you go critical listening way. These aren’t analytical at all, nor what i would suggest for treble head, but the highs have beautiful resonance that are very realist and life like, you’ll hear richness of brush strike in its density more than texture, so can we call the high holographic and hint euphonious, yes, these 2 exotic words describe well what I hear. These are fatigue free highs with good sens of dynamic and bodied presence, high pitch instrument doesn’t feel tamed but well control in loudness amplitude projection, should it be piano, violin or female vocal their no shoutyness, no harshness, no splashiness. And about splash cymbals, it doesn’t feel artificial scooped, just a hint soften in sustain release so the resonance will be there but gently blurred. If i go nit picky, ill say treble lack air, sparkle and extension up to 20khz, and extra 15khz spike for brilliance and extra snappiness would transform the Serial into TOTL IEM. Add an EST to this and you’ll enter end game territory. So, some instrument will feel a bit lacking in proper presence authority and texture like electric guitar and clavichord, for ex, even in chamber orchestra of baroque classical, the clavichord will tend to sound more distant than violin, piano and cello. Nonetheless, like bass and mids, the treble is a very versatile one that will benefit more music genre due to it’s charming fatigue free balance.



Spatiality is very wide and have good tallness, we have a full mix of stereo and center stage spacial cue, but it’s not the cleanest or airiest openness since their no scooped dynamic zone, and space is fulfill with wide transparent sounds layers.

This permit a good layering separation, but less precise and accurate static positioning. It’s not bad per see, just not sharp enough in resolution for clean separation definition…a bit like, being to near of your sound system you know, to get fully immerse in thick musicality, to get goosebumps instead of cerebral enjoyment.

So, while i consider resolution rich in colors nuance and instrument presence fullness, i don’t consider the Serial king of technical accuracy, precision of definition or micro details generosity. My real qualm would be lack of proper sound info above 10khz.

Attack speed is good, but not balanced armature or even planar fast, it’s not very edgy yet not out of control. The edge is hint blunted but in an appealing euphonious way which make result rounder than edgier. Its still above average and im impress that transient response of 3 drivers seem similar, this keep dynamic balance cohesive.

All in all, the use of 3 dynamic driver permit a dynamic articulation without muddiness that would be impossible with all single DD iem apart perhaps Final Audio A8000.




Let’s say that the 3DT follow the opposite musical balance than Serial by focusing more on instrument texture presence and definition than their body and note weight. The result is brighter tonality with less boosted bass and more upper mids and pina gain boost. The resolution is sharper, texture is more detailed but the sub bass is more roll off too, timbre is thinner dryer and overall presentation less wide open and more about center stage compression.
Serial is bassier, warmer, lusher and more natural, it’s smoother less prompt to sibilance and timbral imbalance too.I did praise the bass of 3DT, but its very different, its cleaner and better separated, mid bass is faster and kick drum better reconstitute yet bass line are harder to follow, less vibrant and bodied and more about beginning of attack for acoustic bass as an example, you will hear better the slapping texture and articulation yet not the extension of it which will get fastly low in amplitude while with Serial it will open in lush resonance, for rumble lover the Serial is notably more enjoyable, sens of weight and dynamic in whole spectrum is better too.
Mids are less recessed with the Serial, apart upper mids which are more forwarded with the 3DT. Vocal sound less wide open and well layered with 3DT, timbre isn’t very appealing and in fact you tend to get distracted by the very generous amount of details. Piano presence is better carved in definition, texture of note is richer yet the weight is lacking and sometime higher pitch go trebly, so, higher note will feel more dynamic while lower mids and mids note more distant, making the listen a bit uneven even if strangely captivating.
Treble is very different, way brighter, more brilliant and generous in micro details, more snappy and perhaps faster, more extended too but to the cost of a more V shape imbalance too where percussion will tend to stole the show of every other instrument in jazz track for example, as well, 3DT extract more background noise artifact and texture grain that perhaps aren’t beneficial for musicality. Nonetheless, who know what will happen if we exchange this very treble DD with the darker one of Serial, perhaps a miracle! I love 3DT treble but don’t find it well balance enough due to mid range recession.
Spatiality is wider and taller with the Serial, just a hint deeper and cleaner with the 3DT, yet, even if space between instrument isn’t the cleanest with Serial its wider to. 3DT feel a bit compressed and intimate in stage, lacking in stereo openness, your a bit stock in ”tunnel vision” which doesn’t create long term laid back immersivity like the Serial.

All in all, those 2 are great but very different in tonal balance, dynamic heft and timbre. I think it wort having both even if their no doubt i prefer Serial for its lusher fuller musicality and notably more appealing vocal. 3DT are for those allergic to warm, dark or bassy soundsignature and in that sens, they are great. Technically speaking, 3DT is a notch superior, both in attack speed and resolution, yet tonal balance it’s his achiles heel.

VS KINERA URD (2DD+1BA+dual EST-650$)

The URD are more than 2 times pricier and don’t feel like so apart perhaps treble part covered by EST driver which is faster and more snappy-sparkly. Tonal balance is a bit different, though a bit dark too it’s more U shape and mid range is notably less dynamic, hint more recessed and thinner. Bass doesn’t have the chunky slam of Serial, nor the layering, kick drum is even more dark and lean sounding but sub bass line are cleaner.
In term of dynamic heft, the Serial feel more W shape and energic, offer heavier note weight and thicker fuller more forwards male and female vocal.
Timbre is richer too than URD which have liquid one. Everything sound a bit hall like and distant with the URD compared to more in your face presentation of Serial, this tend to offer slightly cleaner and crisper imaging, but the mids are less immersive.
Highs are darker in mid treble region, so its even more soften in texture and bite, making electric guitar more recessed, less bodied too, but permitting higher transparency which will benefit strings quartet for ex. Serial sound less sharp and brilliant for instrument like clavichord, and add more low harmonic body to acoustic guitar, which will sound thinner yet more airy, delicate and sparkly with the URD. You know when I say the Serial need an extra EST to become TOTL IEM, well, its exactly to add this sens of air and top openness that the URD offer, i can say the URD would need the treble DD of Serial to become end game IEM too.
Spatiality is more open and deep with the URD, but the layering of mid range is lacking, so here we have big tall stereo wideness with scooped center stage will center stage seem super stretched with the Serial.

All in all, while both these IEM are darkish, bassy and smooth sounding with wide spatiality, the URD sound less natural and cohesive between its driver, overly soften in texture and thinner in timbre. Apart the EST treble, they aren’t superior technically and tonal balance is fuller, less U shape and more natural with the Serial, so it’s an evident win i feel, at least in term of sound value.


Ok, now its the fight that will tell if we can get any advantage with multi-DD IEM against a very capable single DD. The SM2 are perhaps the best technical performance out of a DD you can get under 300$, but the tonality is near polar opposite of the warmer Serial, while Serial flirt a bit with (punchier fuller) Harman Target, the SM2 goes DF neutral its own way. SM2 is brighter with way louder pina gain and treble emphasis, bass is lighter and more rolled off in sub bass, their no proper chunkyness or rumble to it but its more textured, faster and better define in resolution, yet its not as well layered and fully restitude in body. Mids are notably thinner, more distant and artificial sounding, male vocal are notably less bodied while female vocal more agressive and less well rounded, less wide and again well layered in dynamic presence too. Yet, SM2 resolution is notch higher even if it can feel forced while its more laid back, warm and dense with Serial. Vocal and instrument tone is more natural, while presence have boosted textured and edge with SM2. When it come to treble, it follow similar path, its sharper and more agressive and analytical with SM2, it seem to extend more too since we have more air, brilliance and sparkle, but mid treble lack the Serial fullness and some instrument and percussions will feel bodyless with the SM2, nonethless their no doubt Serial is Darker and less generous in details retrieval.
Spatiality is so different here, while the SM2 seem more open and airy, it feel scooped in center stage, where the Serial stretch it wide and fowards. So, Serila is wider and taller yet not as deep, but it feel like well, have 3 speakers instead of just stereo separation.
The imaging is notably more articulate in layering with the Serial, while positioning accuracy will go to SM2 for static instrument since its crisper and cleaner sounding.

All in all, SM2 is more clinical sounding but sharper in resolution and faster in attack, yet tonality is fuller, thicker and lusher with Serial and way more musical and natural, bass and mids are more bodied and fowards and layering have more dimension to it making it a more versatile and immersive sounding IEM. With SM2, i listen music with my brain while with the Serial, it’s with my soul.



I think it’s evident I have quite a big love affair going on with the Penon Serial, and while they could benefit from extra treble extension, i’m far from thinking it’s a deal breaker.

The fact that Serial offer a lush cohesive musicality with 3 dynamic drivers is a tour de force by it’s own, these are perhaps a dream come true for bass and mid range lover that seek for an all-arounder that is safe for long listening, yet heavy in dynamic articulation.

I own about 200 earphones, and none of them offer this sens of holographic layering where the bass player is fully extract or vocalist widely open and enveloping. Sure, i can nit pick that instrument separation isn’t ultra clean or micro details feel recessed, but at they end, we are charm by musicality and the Serial know how to sign with colorful passion.

Add to this the beautiful design, and very generous accessories, and it’s an easy recommendation for 300$. Now, I have the UM 3DT for bright side of tonality and Penon Serial for the warm side that isn’t lacking in richness, for supreme all arounder, i would suggest the Serial without a single doubt unless your are a treble head.

Highly recommended for bass player or lover, male female vocal fans, those who seek holographic layering that single DD can’t achieve, those who appreciate natural dense timbre and those who listen to wide range of music like me from classical to jazz to electronic to soul to.…

Penon isn’t amateur tuner and their long experience in audio world is beautifuly showed with the Serial. Again, Bravo!

PS: I wanna thanks Penon Audio for sending me this IEM after i manifest my intense curiosity about them. Their no $ incentive nor official affiliation to write a positive review. Penon will see this review once published. As always, i’m 100% unbiased and subjective in my sound impressions and appreciation.

You can order the Penon Serial here, they are on sale right now for 270$ (non-affiliated link):

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  1. Really decent writing Eric, can’t find one bit where I wouldn’t agree less. Serial is indeed a fantastic offering, pretty much as the rest of them children of holy PENON.

    Liked by 1 person

    1. thanks mate, appreciate the good words….make me keep up writing! i wish i could describe bass part even better, but people need to heard it themself, thats only way to get it. havent try other Penon IEM, but sure will put Vortex, Orb and Fan2 on my top list to test.


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