General Information

ISN Audio EST50 Flagship 2 EST + 2 BA+ 1 Dynamic Driver Hybrid 2Pin 0.78mm HiFi Audiophile IEMS


Brand:ISN Audio

Model: EST50

2 Sonion Electrostatic driver for ultra-high frequency

1BA Knowles for high frequency

1BA Sonion for middle frequency

10mm dynamic for bass

Rated input power: 2mW

Max input power: 3mW

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

Cable length: 1.2M


ISN EST50 earphone

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New Head-Fier
Pros: Well-executed Highs, Relaxed midrange tuning, Fit and Build
Cons: Coloured Sound and Prominent Bass may not be for everyone


Disclaimer: This review set was graciously lent to me by a friend from his personal collection and the review is written of my own accord. This set was purchased by him from Penon Audio at full price. If this has helped you, do check out our website for more!

ISN is still a relatively obscure brand, with its most successful model being the ISN H40 Hybrid IEMs. The EST50 is supposedly their latest flagship set to continue the path that the H40s have forged. I have yet to try the H40s, and my only experience with an IEM from ISN is their D02 single dynamic driver earphones which I found to be rather mediocre. Many have mentioned the EST50’s change in sound with burn-in. I personally cannot confirm if this is true as the set I borrowed had >100 hours of usage on it. Without wasting any more time, let’s see if the EST50 is a worthy flagship and if it is capable of competing in the increasingly saturated electrostatic tribrid market.

Accessories and Build Quality (Score: 8.0/10)

For a flagship IEM, the EST50 came with rather minimal accessories. Nevertheless, they are of rather good quality so I wouldn’t be too critical. Included is an ISN S8 cable, which is an OCC Silver-plated Cable. It is available for purchase separately on the Penon Audio website for about US$32.50. Upon purchase, you are free to select what termination you would like for the cable, either 3.5mm single-ended or 2.5mm/4.4mm balanced.

The build quality of the EST50 is excellent. It’s what is expected of it as a flagship. The shell is made with quality resin, and the faceplate has a gorgeous wood grain pattern. The 2-pin socket is nicely flushed and can take many other third-party upgrade cables as well. My only “gripe” with the overall design is the ISN logo on the faceplate looks a little tacky but don’t let me stop you from vibing with it.

Fit (Score: 9.0/10)

The stem of the EST50 is on the wider side, but still slimmer than that of the Moondrop Blessing 2. The stock tips are 2 sets of silicone tips with different bore widths, which I swapped out for my own tips. Wide-bore tips like the JVC Spiral Dots fit my ears brilliantly on the EST50 and also has the best effects on tuning out of all the tips I tried. I will elaborate more on my experience with the Spiral Dot tips in the sound section.

The shape of the shell is very well-contoured and offers a near custom-like feel. I can’t speak for everyone but it fit my below-average sized ears perfectly.

Sound (Score: 8.9/10)


Frequency Response Graph of the ISN EST50

  • Lotoo Paw S1
  • Hiby R5
Music listened to
  • Chicago Symphony Orchestra – Beethoven Symphony 7
  • Boston Symphony Orchestra – The Nutcracker Suite
  • The Vamps – Cherry Blossom
  • Stevie Wonder – In the Key of Life
  • Bastille – All This Bad Blood
  • The Lumineers
  • Børns – Blue Madonna
  • McFly
  • Avicii
  • Coldplay
  • Fun.
  • Family Company

The ISN EST50 has a downward sloping sound signature. It shamelessly rocks a powerful low end with a deep extension. The warm tuning gives a rather coloured sound, which won’t yield the most accurate tonality or analytical sound. I found the bass a little overly pronounced for my tastes and a little too blunt for an IEM in this price range. Personally, I would have preferred a faster bass response to provide some balance for the bass presence. This is especially so when listening to Pop/EDM tracks where the bass can become borderline overpowering almost to the extent of boomy.


Fortunately, things got much better moving into the mids and highs. As expected looking at the frequency response, the vocals and upper mids are a little held back and rather relaxed in energy levels. The balance was a little off in my opinion but those who would want a more laid back tuning would love how the mids are presented.

Switching to wide-bored tips helped a lot and made it very much more enjoyable. My tip of choice was the JVC Spiral Dots and it worked wonders for me. It cut back on the midbass bloom and lifted part of the veil over the mids. My impressions of the mids after the tip change is mostly positive. The mids were never too forward, vocals were very nicely bodied yet crisp. Upper mids are tame in an enjoyable manner, without compromising on detail retrieval.

The separation of musical layers was very nicely done, proving the EST50’s technical prowess.


The highs on the EST50 are no slouch. As expected of a good electrostatic driver implementation, the treble extension is impressive and expansive, giving a very nice sense of space. Instruments like castanets, cymbals and jingles have that added dimension to their timbre, enabling them to come to life. There are no sibilant peaks or weird timbre/tonality issues here. Natural, controlled, yet very good with microdetails.


Nice Imaging and width of the soundstage. The tuning of the EST50 is a little reminiscent of the Thieaudio Legacy 5, but with much more refinement in the bass, which was the bottleneck of the L5 in my opinion. That said, I still feel there is room for improvement in the lower end of the EST50.

Bass quantity is a little too much for my preference, and I tend to not enjoy downward sloping signatures too much as I prefer more energy and presence in the vocals. The bass gets a little satiating to listen to after a while. The colour injected into the sound due to the way the bass and lower mids are tuned can be a little overly unnatural for purists to tolerate as well.

Nevertheless, there is something addictive in the mids and highs that give the EST50s their own X-Factor. I’m confident that there would be fans of this set with its tuning. Just perhaps not too much of a fan given my library and tastes.



Coming into this review, I had limited experiences with ISN IEMs and I could not help but wonder if they were ready for flagship competent enough to compete in the already competitive tribrid market. It’s safe to say I wasn’t let down and this can be considered a good tribrid implementation with a niche but well-executed tuning. That said, I did have my gripes with the bass and overall tuning and tonality.

At the end of the day. if the EST50’s are your cup of tea, they may well be worth the investment and no doubt be a joy to listen to.

Overall Grade: B+​

Click HERE for our grading list for earphones


Headphoneus Supremus
ISN EST50 the rich and the bold
Pros: 2 pin semi custom all resin ergonomic shells utilizing some of the best drivers in the industry for sound. 10mm liquid silicone dynamic+1 sonion BA for mids+1 knowles BA for treble+ 2x Sonion EST drivers for ultra highs. Muscially tuned and refined from bass to treble the EST50 is all about getting the best out of your music. Easy to drive. Very comfortable with a minium 26dbs of passive isolation. Made for eclectic music lovers as it has bass full bodied mids and extended EST treble. Not so picky of sources. Scales nicely with better cables. Nice new pouch.
Cons: Minimum accessories pack which comes with only two sets of tips and a standard SPC ISN S8 cable. Your better cables are highly recommended to bring out the best in the EST50. Absolutely requires a full burn in for the dynamic and EST drivers.
ISN is a brand that was introduced by Penon audio which initially started with more affordable earphone cables on Penon web site. My first IEM cable I bought from Penon actually was an ISN cable, I believe it was the old ISN C16 which is still to this day one of the most unique copper cables in the market that is only on Penon web site.
ISN C16 shown with EST50
Then they started to make earphones and I think the community is very aware of the ISN H40 which to this day is one of the most successful releases for ISN. With great success comes the responsibility of advancing what was set. However the type of sound the H40 was and still is one of the best value hybrid earphones in the market. To truly do one better, ISN is gonna have to step up.

So how does ISN advance the H40 design? They had to go tribrid and utilize some of the best drivers in the industry and that is how you one up the H40. However it is not all about just adding drivers it has to do with that musical tuning of the H40 the reason why folks gravitated toward that sound. The good news here is they actually were aiming for much higher end sound in the EST50 with the same pedigree as the H40 sound tuning. So what happens when you throw in two highly regarded Sonion ESTs and a unique potent 10mm dynamic with the inclusion of a single Sonion BA for mids and a Knowles BA for treble.
Before getting into this review standard disclaimers. I was provided with a review sample from ISN and you can purchase a set for you here. Their website here.

What makes the personal audio hobby interesting is that there are always new advancements in the types of drivers produced that promise advancements in 2 channel stereo for our ears. Just the sheer variety of dynamic driver types, BAs types and now Sonion has made some waves with their relatively newer Electrostatic drivers. Hybrids are so yesterday. It is all about the tribrids nowadays. EST drivers are interesting as they seem to be utilized for just the upper treble portion of a earphone design. I was told Electrostatics have some difficulty with lower treble frequencies so the upper trebles seems to be where they are utilized the most and this is the case with most earphones that utilize EST drivers. EST sound is a bit different than your standard BA for upper treble designs which is best described as the perfect sound sauce for the treble region. What I mean by that is ESTs innate ability to add air dimensional ques with precision and nuanced details to treble notes is uncanny. There is a reason why some of the highest end earphones in the industry are all gravitating to use the Sonion electrostatic driver for their designs.
What's included.
The shells, the ISN S8 cable which is your standard SPC 8 core variety of cable the good news is this cable matches up well with the sonic ability of the EST50. Even better you can choose single ended or balanced termination when ordering a set of EST50s The bad news is I wasn't expecting a treasure trove of tips but 2 sets? Again it is not all bad as the green silicone tips they included matches up well with the EST50 here again. I suppose as long as they include something that works well. The new green case they included is a magnetic lid clamshell case which reminds me of the old Sony cases that was included with the old XBA earphones. Nice newly designed case is much better than the generic zip up rectangular cases they used to provide. To be honest I am a bit disappointed with the accessories here but that is not the reason you are reading this review.
Drivers are the foundational aspect of the sound design but then it comes down to the type of tuning each manufacturer decides to grace these drivers with and then you get the final product. It has dawned on me that ISN does not go for a ruler flat type of sound but more so the type of tuning that allows for full music immersion. Some may call it analogue in quality, old timers will love the tuning that ISN has bestowed on the EST50 as the tuning incorporates a lot of what makes them older studio recordings shine.

But then utilizing some of the best drivers available for the cost means these have the technical ability to get you into your music no matter what you listen to.
Sound tuning is best described as a balanced L shaped frequency design with a modest 6 dbs or so of pinna gain with the most emphasis toward the lower end especially sub bass. This particular design and the choice of drivers here has a lot to do with how well received last years H40 was and still is. It is clearly an attempt at doing one better than the class favorite and here we have a continuation of that classic musical design of the H40. Now utilizing premium drivers.
It is what you would expect. More of everything that counts the EST50 is a no holds barred full bodied musical sound signature that has everything to do with enjoying everything about our music. It is what I would imagine a true successor to the H40 can only be. Heralded as their flagship model the ISN EST50 has upgraded more than just the sound tuning.

Sound analysis was done using my DAPs Fiio M15, Shanling M6pro, M5s, M3s,Ibasso DX160, Sony ZX300, Cayin N5ii, Pioneer XDP-30R, Ibasso PB3 and IFI BL for amping.
A word about burn in.
Truth is some earphones don’t do a damn thing with burn in and some do. The EST50 clearly does. Out of the box you're greeted with an overly warm sound and a bass end you best be prepared for. Lets just say I thought the bass driver was broken. I have heard flabby thud one note bass before but I was not expecting it on the EST50. But that is what you're greeted with but alas burn in will and does changes everything about the sound on the EST50. You better believe the silicone dynamic and the EST drivers need a good burn in. Not so much the BAs. You can tell how the sound is going to be but no way does the open box experience result in what you're actually gonna get at the end. So I highly advise folks to run some music at moderate to lower volumes through the EST50 for a week and then take a listen.
EST50 sounds.
So it was apparent to me even on open listen that this tuning was going for a bold sound and has nothing to do with an analytical approach. There is nothing on the sound that is neutral or flat. You don’t buy a mid fi category tribrid with 3 different types of drivers for the design to analyze your music, you buy it so you can enjoy your music to take full advantage of the three driver types. This is what these are all about. Big bold musical, richly dynamic and very immersive, The EST50 is clearly the successor to the H40. These are optimal ear speakers to listen to your eclectic music collection. It is personal audio at its finest and I am glad that ISN has approached the EST50 with this angle.

EST50 has a touch of warmth to its tonality as did the H40. I would put the sound of the EST50 into a technically balanced presentation with an underlying design of musically dynamic in the category of sound profiles. No point in the tuning are they overly analytical but at the same time these are clearly showing advancements due to the premium drivers ISN is using. I will do a more complete comparison with the older H40 toward the bottom of the review but for now just know these are clearly an update on what made the H40 so good. You get a similar stage expansion but each part of the sound design gets a dedicated upgrade and refinements..
Earphones have this or it doesn't. The EST50 could be called EST50 the Bold. Cus bold sound is what is going on with the EST50, be warned however that the EST drivers don't really fully open up till you get that burn in to take effect. Once it does you get the traits of what EST drivers do. A potent deep reaching bass and a lush rich mids presentation. That dimensional quality to the treble is full on and has excellent smooth quality extended trebles that inject some air with pinpoint presence to the trebles, this in turn results in some of the best quality treble in the price range. By the nature of the design the lower trebles are not as accentuated as a lot of chifi earphones and hence the EST50 are an easy listen yet treble details abound with a type of sound you can get lost in for hours with no fatigue.

Electrostatic treble, when utilized well, adds a sense of space for treble notes with better nuanced details than your standard BA treble or a well implemented dynamic treble. Sounds decidedly more natural vs something like a piezoelectric ceramic tweeter, with the ability to extend extremely well injecting air and articulation to treble notes to the upper mid portions of the sound profile. A well implemented EST can be the difference between dull treble to sparkly extended crisp dimensional treble that completes a tonal quality to the fullest. EST50s has a refined treble end as it is utilizing a single Knowles BA to do lower treble notes and two ESTs for the ultra highs. This combination of ability and natural tuning for the highs make all the difference. Treble sounds absolutely superb with the right sparkle and shimmer on the EST50 using 3 higher end dedicated speakers just for the region. This allows the EST50 to have a higher level of treble many earphones are lacking in.
The transition
To the mid bands are seamless and here is where the older H40 shares some similarities to the new EST50. Mids have always been great on the H40 and here we see an uptick for the mids ability due to an upgraded Sonion BA doing the mids duties. Sonion BAs have a tendency to have a richer tonal character and this is clearly evident even on open listen. A single bore of the EST50 is dedicated for the mid bands hence mids are full on. There is no mistaking that tonal quality of this Sonion BA added a full rich sound. Folks that love their mids to have good, body, weight/ substance and fullness in quality, the EST50 mid bands are right up there with the best the designers have ever made. Folks that have heard how good mids are for the Penons own Spheres, Orbs, Globes, and Volts will immediately recognize the tonality and presence of the mids. The EST50 has nothing to do with a thin skinny sound. How many times have you read a review of an all BA set sound description where mids take the crown and the treble and bass are a step back in quantity and quality. On the EST50 you're essentially getting it all. There is nothing holding it back. You're gonna get the full monty experience for sound.

You can’t call an earphone a flagship level with anything held back is my point. The sound is full on with the EST50 and you're going to appreciate not just the balancing act to get that sound right but just how capable each portion of the sound bands truly are in the EST50.

Technicalities on the EST50 are supreme and has great layering to instrument placing/ imaging in the sound field you're listening to. This aspect clearly shows the refinements for the mids that their previous earphones showed aspects of but is not quite as good as it is on the EST50. Mids are more than just the best aspect of the EST50 but then if you have basslines for your music you listen to that is where things get really interesting.
A potent BASS
Bass has always been a foundational aspect of ISN design. All their earphones have bass emphasis but here we get a highly specialized 10mm liquid silicone diaphragm for bass on the EST50. This isn’t your garden variety bass we are talking about here. Bass has a presence, roundness, a supreme elasticity, authoritative rumble and reach. Bass is the foundation for a lot of music I listen to, be it rock and metal to jazz to hiphop and EDM. And I can tell you. Bass is not an afterthought or does it play a supporting role in the sound design for the EST50. It is featured.
ISN managed to squeeze bass potency, presence and ability all through one of the 3 bores to your ears. This bass takes that musical bass of the H40 into a different level. Again burn in is highly recommended for the dynamic driver to really strut its stuff. The difference in tone from out of box to where I have the EST50 bass drivers firing off now is remarkable and completely different. The quality seems to get better and better as they age. Here we have bass presence to the likes of some of the best bass performers I can think of for hybrid/ tribrid designs.

Mid bass has a bit less emphasis vs the sub bass but both are represented extremely well for your music. I can say if you're the type that purposefully are looking for a weak limp bass tuned IEM then you should most definitely look elsewhere. Again nothing is neutral on the EST50. Bass has clear coloration and a boost to it that makes your music come alive with a lower note that has some extreme qualities.
This rounded bass has a mid and sub bass presence with a steady increase of sub bass to about 12dbs. That is not really extreme per se but since the dedicated dynamic here seems to excel at bass, it sounds more emphasized than the graph shows. I own plenty of earphones with what looks like similar or more bass emphasis but the bass end of the EST50 makes you take notice.

Its tonality is absolute. Defined bass notes of the EST50 has a rawness and power to the bass notes that is akin to an amplified dedicated woofer. It does sound more like speaker bass and that is amazing coming from earphone bass that is only 10mm in size. Texture of the subs here is nothing short of remarkable with a tighter yet beefy bass note from mid bass and sub bass authority. Sub bass decay is some of the most realistic I have heard and is comparable to the best I own, even my IER Z1R. However with bass authority comes the complaints that there might be too much bass emphasis. I don’t think so, the sound design has a large enough stage to encompass a stout bass end and here in the EST50 the bass dynamic is clearly a bass specialist. Bass punch for bass punch I bet the EST50 punches a bit harder. Rumbles a bit more than yours. Sub bass sustain with a slower decay and sounds like you have dedicated subs in your EST50 and you can most certainly look at it that way. Bass is a part of the EST50 sound design so you should clearly know this before buying a set. You're not going to hear a brawny bass for every type of genre you're listening to. It will come down to how much bass your music has in the recording. With that bass authority and good passive isolation of the EST50s I find them perfect for outdoor activities. Last thing you want when out and about is a limp noodle bass end from your tribrid. I am happy to report the EST50 has a good healthy amount of bass but nothing that is going to ruin your orchestral scores or vocal tracks but you will get a nice ear lobe rumble when listening to EDM and hiphop.
In the end
The EST50 is a compelling product. I can clearly tell what the designers of the EST50 are going for. It is more than just one aspect of the design that shine on the EST50. You are really getting all of it. They are more than just catering to bass enthusiasts it is catering to mids fans and capped off with a complete treble that has high quality and extension capped off by a large immersive stage. It is personal audio with a no holds barred sound signature. Yes it is a colored tuning but I bet your earphones will sound boring after hearing the EST50s. The big question is. Are the EST50s a true upgrade on the previous H40? Not only are they a true upgrade. These will be an upgrade to many earphones that are hovering around this price range. Especially if you love your bold full bodied sound. There really aren’t too many choices for earphones in this price range that does exactly what the EST50 can do. That saying you can have your cake and eat it too. This is essentially what the EST50 is. It has great treble, it has great mids, it has great bass, it has a great stage. What more do you want? As always, thanks for taking the time to read and happy listening.
Here on this section I would like to put on here what it is that the EST50 actually does better than the H40 cus many will ask.
VS the H40
First off, even by today's standards the H40 is a supreme value. One of the best hybrids your hard earned money can buy at the price. Both earphones have excellent wider stages, both are balanced well for their given sound designs but when you really start listening to each part of the sound designs that is where the differences start to appear. The biggest being the mids and how they are presented. H40 is not a thin sounding earphone but compared to the EST50 mids there is a drop off in micro details, layering and sound separation in the mids. EST50 has the better depth, a richer tone with better timbre of instruments. There is no question the quality of the mid bands sees a jump in quality here. Hence the mids portray with more realism with better atmosphere and air, so the higher end mids Sonion BA is clearly showing what it can do. Bass especially sub bass has more authority and out rumbles the old H40. Mid bass sounds tighter and more defined even though both have comparatively similar impact for bass. Treble is also more advanced in the EST50 as you would expect. Better treble articulation and detail. More dimensional sounding with better extension and air the EST50 sounds more complete for treble and again it isn’t like the H40 treble is lacking but it is clearly outclassed by the Knowles BA and two Sonion EST drivers.

So from what I am describing it is a more refined experience all around but that is what you would expect.

Vs Penon Globe

I did this comparison against the Globe due to Globe owners wanting me to shed some light vs the two. These two earphones have a lot in common. Sound balancing for one and both are using similar Sonion BAs for mids with similar tonal and dynamic qualities.

You can call the EST50 an evolution of the Globe sound signature. Globes utilize two bores out the nozzle the EST50 has 3. Just by design the EST50 shows better separation of the 3 zones of sound. Both do vocals amazingly well but since treble is completely separated from the mids, the mid bands have better overall definition as a result. Both sound very dynamic and full on. Globes has a touch more upper treble emphasis but it is the EST50 that has the better treble extension and sounds more complete for treble with a better sense of air due to the EST upper treble sounds more rounded for treble notes.

On graph it shows that the Globes might have more bass emphasis but it is actually the EST50 seem to have a slight edge in impact, bass extension and texture.Globe bass end sound more like full bodied earphone bass. The EST50s are more approaching speaker like bass. EST50 simply has more authority, a bit more in the way of quantity and most definitely an upgrade in quality.

EST50 shows a slight uptick in imaging and sound separation, an enhanced Globe technically. The EST50 and the Penon Globes are closer in tonality, stage and ability vs the H40 but the EST50 does have the upper hand against the Globe when it comes to micro details, a more dimensional extended treble and shows a bit more authority for sub bass performance with an increase of texture.

EST50 vs Volts
I consider the EST50 Volts younger brother. They share some striking similarities in sound balancing using similar type of drivers too. Volts are like the grown up version of the EST50 sound design. Both earphones leaning more toward musicality, fullness and immersive qualities of sound balancing.

Both earphones use a 3 bore design so more similarities there but the Volt has more refinements for its sound design, a wider deeper stage vs the EST50. To be fair it isnt like the EST50 has a weak or closed off stage. It is just that these higher end IEMS do put focus on stage and depth of the sound. In fact EST50s has a remarkable surround like stage due to how musical they sound that is in no way claustrophobic or closed in sounding. EST50 stage is actually pretty excellent about par with the ISN H40 actually.

The difference are in how the drivers were utilized, On the volts the mids are using both Sonion BAs, the EST50 uses a single Sonion BA for the mids and one knowles for treble. The Volt is using the quad ESTs for treble. It is known EST drivers struggle a bit in the lower trebles so by default EST drivers are more about extension, air, dimensional qualities to your treble.
Since the EST50 has a dedicated BA doing lower treble it was tuned to be proficient there but the sound tuning has the treble not being so prominent which again is a fine balancing act here. Where the EST50 stand out from the Volt is its bass presence. Volt has some good bass but to my ears is a bit more even handed with the balancing.

EST50 bass is not so much more emphasized but this silicone dynamic being used is most definitely catered toward bass fans. Sub bass especially has emphasis to the likes of some of the best sub bass performers I can think of including my IER Z1R. Mids strike a very similar tonality and forward presence but the difference again is a bit like how they are compared to the Tansio Mirai LAND and how those were tuned with two BAs doing mids. Volts has better imaging and detail in the mids due to both Sonion BAs being used there and mids has more of an airy quality as the stage is more enhanced on the Volts as well. Treble presence and extension is the most identical between the two with Volts exhibiting a bit more airy quality to upper treble notes. Volts shows a more tonally balanced and basically more refinements and again more technical yet uses a very similar sound balancing as the EST50.

Essentially your getting 90% of the Volts performance at almost half the cost. Laws of diminishing return is happening here. EST50 with a upgraded cable comes even closer to the Volt. Volt with an upgraded cable takes off into a different stratosphere in sonics however so if I was comparing both units with upgraded cables it would not be a fair match but as they are the EST50 comes strikingly closer to the Volt in performance and is also able to show some uniqueness due to the bass driver that is again Stout in what it does. For folks that have never owned the Volts the EST50 will surprise in many ways if you end up getting the EST50 your really getting a bit of the Volt magic with them. Both are supremely musical in their presentations. If you can imagine what the EST50 would sound like with even better refinements that is in fact what the volts are.

As similar as the EST50 are to the sound balancing to the volts they clearly have their own sound and tuning involved at a bit over half the cost of the volt the EST50 I can say is got some good value to what your getting. Especially if your a bass fan.
Cables match ups.
Stock cable is the exact same cable that was included on the ISN H40. The ISN S8 which is a classic ISN cable and one that matches up well with both the H40 and the EST50s however. No way is this basic cable going to optimize the EST50 to its full ability. Here are some cables suggestions that can really bring up the strengths of the EST50 and make the sound even better than what was provided.

First off, don't be afraid of using pure silver on the EST50. Due to the moderate treble emphasis and ample bass emphasis of the EST50. Pure silver matches up extremely well with the EST50. Of course not all silver cables are the same. So the sound comparisons using these cables are against the stock ISN S8 cables. As good as the stock cable is. EST50 sounds better with higher end cables.
First we have the Penon Mix. I did a review here. The Mix turns out to be a great match for the EST50 as it is half crystal copper and half pure silver. This cable enhancing ability is very well balanced in what it does and I noticed an uptick in clarity due to the pure silver while maintaining the great mids and bass presence due to the copper aspects. You also get a benefit of a more expanded stage when using the Mix. The Mixs highly resolving ability for a moderate sum is ideal for well balanced tribrids like the EST50. Better resolving with excellent dynamics and an expanded stage is what you get on the EST50.

Next is the ISN AG8, review shown here.
When I mentioned not all silver cables are the same. Take a look at this bad boy. One of the very best unique pure silver cables in the market. Unlike a lot of pure silver cables that thin out a sound. The sheer physical makeup of the thicker cored AG8 matches up with the EST50 as it adds an element of a thicker sound vs your standard pure silver cables. The AG8 enhances everything about the EST50 with a tighter bass note, a cleaner sound and the widest stage possible. Silver does enhance detail and you get that with the EST50. The AG8 was the very first cable I threw on the EST80 and it will be a tough choice if I want to keep the AG8 or the Mix on the EST50 once I am done with my review. Good news there is I can always switch up when I want to. Choices are always a good thing.

Last but not least A flagship earphone deserves a flagship cable
ISN Solar. I did a review for here
Now we are talking true higher end level sonics. Solar enhances with even a richer tonal character due to the gold plated cores. Enhances stage, not quite like the AG8 but more like the Mix and adds a more rounded note definition for trebles. Bass sees a slight uptick in rumble and imaging is enhanced, treble is smoothed out but clearly defined. The Solar costs almost as much as the EST50 but when you combine these two. It is like a long lost puppy that found their way home. The match up is undeniable. Solar enhances that musicality with an enhanced richness, better instrument separation and adds a more tangible air to the sonics that none of the other cables can do. You want maximum EST50. You gotta pay to play. I would say with the inclusion of the Solar on the EST50 I can see how the EST50 will put up a fight with your more expensive in ears. The EST50 is clearly enhanced and takes a liking to more better cables.
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I'd love to try these, great price for the tech you are getting.
I was wondering if the ISN SC4 cable is a good choice or not for replacing original cable of EST50?
It is a good match. larger airier sound using the ISN SC4. A bit more spacious and detailed due to more silver influence.
I also like the Penon Mix with the EST40 as well.
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