ISN EST50 – Refined fun!

If you're looking for the next step in your audiophile journey coming from ISN H40/H50, the EST50 certainly does feature one of the best bass around in the segment but also adds a very engaging and more technical midrange with a refinement that it's pretty impressive at this price point! If you don't know ISN or were looking for a more balanced and refined presentation than the H40 then I strongly suggest you give them an audition! 


  • Very Coherent tuning
  • Remarkable stage size with precise imaging
  • Powerful and fun bass with good extension and textures
  • Engaging and articulate midrange
  • Mature, refined and engaging treble
  • Excellent value for money


  • Snappier and faster bass would have brought the EST50 to further heights (not evolved much from H40)

Product page :
Price : 459$

Fit, Build & Isolation

The ISN EST50 mirrors my experience with the H40 : build is good with solid and well finished black resin shell. The shells are on not very big per say but deep and protrude a bit from the ear. This is not an issue unless you want to use them lying on the side in bed. Comfort is great and once in your hear you quickly forget them. Like the H40 isolation is quite good for a universal. The stock cable appears to be the ISN S8, a nice 8 wire Single Crystal Copper Sliver-plated which has impeccable build, I have received the 4.4 balanced version.


I have known ISN Audio from their reputation as a cable manufacturer providing quality cables at a competitive price, which is also how they define themselves “We are a wire production and R&D factory“. If you’ve read my H40 review you know I liked it very much for it’s a fun punchy IEM, with good technical performance and amazing value for money. H50 was an evolution I didn’t get the chance to audition but this time around with the EST50 ISN is aiming at the mid tier tribrid market with very strong competition althought the excellent Tansio Mirai Land is priced higher at 599$.

I am expecting the introduction of EST drivers a more technical H40 with more air and extension and the ISN fun brand of tuning I am used to.

Let’s see if this holds true!


From the first track I played (after proper burn in) I felt at home with the very familiar bass from the H40 and for sure ISN has capitalized on its 10mm driver and the experience from the H40 and H50 but I also was quite happy to confirm that the EST50 is on a different planefield form the H40. The EST drivers clearly make the EST50 a much more resolving IEM than it’s fun little brother the H40. Although the midrange shares the same philosophy as the H40 being smooth and full there is clearly better separation and everything is more articulate and exciting. The EST50 is therefore more versatile and more suitable to acoustic, jazz or classical. But where it really differ is up top where treble is more refined although less energetic in the lower section as we’ll see.

The EST50 has more air, faster transients which means more precise imaging and a tad wider stage than the H40 which was already a very good performer there. This big stage along with more precise imaging makes for a more effortless listen but also one that makes more complex track much better on the EST50. The overall tonal balance is improved as well and although it’s not neutral, it’s far less colored than the H40 is.

Let’s dig a bit deeper into the EST50 signature!


Like its little brother the H40, the EST50 bass is clearly one of its remarkable feature but has a less prominent feel than the H40. Don’t misread, the EST50 also features powerful bass with excellent sub bass extension, it’s a visceral bass with great impact like the H40 it’s just balanced a bit more by its better upper treble presence and extension.

Like the H40, the EST50 has a bit of a more “romantic” bass, with a softer attack and a bit longer decay. It doesn’t gets bloomy or messy but it won’t be a leaner, tighter and faster bass and I wished ISN had worked this aspect a bit over the H40. The textures on the other hand are excellent and much improved and the bass is more detailed than the H40 by a significant margin.

The EST50 features a “fat” bass with quite a bit of upper bass presence as well making for fantastic impact and percussions in Ayo “Throw it away” had such power infusing an hypnotic rhythm that is such a treat on that track. This also was quite apparent in Marian Hill “Differently”, but on this track with the snappy synth bass I would have liked a bit more snap and quicker decay. Still, bass power is pretty impressive on the EST50 so basshead rejoice!


The midrange of the EST50 is full bodied like it little brother but to my ears, with leaner lower mids than the H40 which makes it more articulate. The ISN H40 could sometimes sound a bit congested and thick, the EST50 is much better there.

I also found vocals to be clearer and more articulate than H40, with similar vocal placement which is fairly neutral. The stage has excellent depth but vocals never sound distant or in your face. ISN has found good balance there in my opinion. Similarly the tonal balance is improved over the warmer H40 and instruments as well as vocals sound realistic with more nuance. This made for a more enjoyable female vocals were the H40 could sometimes make them overly sweet. On the flipside, H40 had more power to male vocals, not that the EST50 is lacking but it’s less flattering and powerful (but still excellent in absolute terms) and more accurate.

The upper midrange is still absolutely safe and my usual Hank Levy “Whiplash” passed with flying colors. Yet, the EST50 has quite a bit more bite than the H40 and it’s welcome for saxophone and violin for example where I found more excitement but also it brought more balance to the mids presentation. A more versatile midrange.


Given how ISN has tweaked the mids, they smartly toned down the lower treble energy to avoid being too energetic with the added upper mids bite. The H40 is more contrasted but the EST50 more refined as one might expect in this price tier.

The lower treble is safe with not hotness to speak of, it’s a more relaxed tuning but certainly not dull. I hear less weight than the H40, which is something I often note with EST over BA at least EST need quite a bit more powerful sources to carry sufficient weight. The EST50 is no exception.

On the flipside, the upper treble extension is excellent and the upper treble also has more presence with much faster transients than the H40. This is very distinctive and a very significant improvement over the H40 that clearly sets it firmly in the excellent performer of the mid tier tribrid segment.


The EST50 is a much welcome introduction in the mid tier tribrid offering, but facing a fierce competition of the higher priced Tansio Mirai Land and similarly priced Dunu EST112. It features the fun brand of ISN sound that many have come to love with a more serious take on its success recipe.

This makes the EST50 a very strong proposition in the segment with its fun bass, more balanced and exciting midrange and more refined treble. The mid tier tribrid is kind of a sweet spot in my opinion providing better value than mid tier all BA IEMs, reaching levels unheard of at this price point with a gap closing in with higher tier IEMs. This is a sweet time for audiophile on a budget!

If you’re looking for the next step in your audiophile journey coming from ISN H40/H50, the EST50 certainly does feature one of the best bass around in the segment but also adds a very engaging and more technical midrange with a refinement that it’s pretty impressive at this price point! If you don’t know ISN or were looking for a more balanced and refined presentation than the H40 then I strongly suggest you give them an audition for I am sure that ISN is a brand to watch that will grow further up into the higher tier pretty fast!

Listening notes
I spent approximately 35 hours with the ISN EST50, listening on iFi Audio Go Blu and FiiO M17 balanced with the stock cable. 

Special Thanks
Thanks to ISN Audio for providing a review unit of the EST50As usual, this review is my honest opinion. No incentive was given for a favorable review. 


  • Leather Carry case
  • Cleaning tool
  • ISN S8 cable single ended or balanced
  • Tips


  • Shell material: resin
  • 2 Sonion Electrostatic driver for ultra-high frequency
  • 1BA Knowles for high frequency
  • 1BA Sonion for middle frequency
  • 10mm dynamic for bass
  • Impedance: 18ohm±10%(@1kHz)
  • Sensitivity: 100±3dB(@1kHz)
  • Frequency response: 15Hz-70kHz
  • Connector: 2Pin 0.78mm
  • Plug: 3.5mm audio , 2.5mm balanced , 4.4mm balanced

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