Headphoneus Supremus
Pros: Increased richness of tone
Somehow excels in results the more detailed the IEM?
Improved soundstage abilities
Blacker background and enhanced separation within that stage
Increased imaging and itemization, all the while staying close to neutral
Amazing spacial abilities without the use of silver
10/10 on the ergonomics scale
Very little cable noise when brushing against stuff
Still an amazing value when you try and compare the sonic qualities to other similarly priced cables
Increased depth
Improved bass detail and texture
Increased pace and PRaT
Cons: Expensive
Seems to not enhance darker IEMs the best

The ISN GC4 Cable


As far as cable additives go the GC4 ends-up a middle-priced or an expensively priced additive, depending who you (and your bank account) are. Now I would be remiss if I suggested the GC4 doesn’t have a distinct personality because it does. Yet reading that you may think the GC4 emits color which changes the overall tone in contrast to neutral? In reality the affect of the GC4 sounds almost close to neutral due to the pure resolution and clarity it performs. But not neutral due to the GC4 not really going with every IEM. Dsnuts explains that the GC4 is at its best with joined with detailed IEMs, and I found that to be true, somehow expanding and separating the imaging present. While adding detail and texture to the bottom-end, still at the expense of a little bass quantity. The end reality is the GC4 is not for every IEM and DAP combo yet that same strict demeanor makes it a performer when you find the right match-up. In the end my journey was exciting and slightly perplexing as I found my way in, a way into sonic bliss with the ISN GC4!

Penon/ISN description:

ISN Audio GC4 Single crystal copper Pure gold-plated HiFi Audiophile IEM Cable


Brand: ISN Audio
Model: GC4
Material: single crystal copper plating pure gold
Number of cores: 4 strands, single strand is 16 cores
Sheath: environmental protection transparent PVC
Aluminum alloy CNC cutting integrated slider
Secondary oxidation gold foil gold ring
The solder joint is silver–contained tin
Rhodium-plated plug
Cable length: 1.2M

On the surface it seems they replaced the silver plating many cables have with gold?

Per Dsnuts
  • Silver for its highest transparency and stage enhancing.
  • Gold for that rich tone and depth.
  • Palladium for that remarkable imaging and detail.
  • Copper for body and warmth.
Now reading this (to me) it seems that the GC4 would use its copper and gold to add rich tone and warmth? Really the GC4 isn’t about such things, it kinda is, but there is so much more. Why, because there is a unique soundstage imaging and resolution that is the cats meow, seemingly brought even more forward due to the blackness of background and slight refinement of bass. There is a substantial thickness to the imaging but the pinna gain region is not placed forward as you would have with a cable like the Penon Vocal. So that is why Dsnuts explains the ISN GC4 is not a good match for warmer IEMs, as there is an expansion spacially to the midrange, only it’s not boosted in the ear-gain region tonally. But the spacial expansion almost gives the feeling of the cable being more forward, if that makes sense? Let me use examples as the very best way to get my points across.



The Noble Audio Kaiser 10 Encore IEM with ISN GC4 Cable:
I have to laugh here. If you know me and my reviews I will often put a great combo right-up-front to kind-of lead-off the party. And this combo is amazing. Where the other Copper/Gold combo I have used with the Encore was the Penon Obsidian, still this cable is almost opposite in a way. Yep, the Obsidian is about the silky thick lower regions adding warm presence and smoothing everything out a smidge. But here no, we are exploiting the Encores crazy treble/upper midrange shelf to obtain a style of wide resolution. And the bass……more importantly the lower midrange is leaner and faster, making this upper midrange/treble shelf seem that much more forward. Yep, I’m almost in tears and I never cry during these tests but now I am. It’s just a way I never thought possible for the Encore to sound. Now to bring things down to Earth, this style of playback is best with the warmer Sony WM1Z as opposed to the more mid-centric Sony WM1A. Where the midrange boost the Sony 1A has naturally boosts the midrange of this cable over the top in my uses. In fact that one subject is in specific reference to the transparency which is going on here. You see the more a cable shows you the personality between players, the more you can understand the detail/clarity of the cable. I mean here I’m surprised as I started out with the 1A, and I thought the ISN GC4 and Encore were a no-go, but then a few days later joining it with the WM1Z was total amazement. I mean I’ve spent a total of 23 days getting to know the GC4 and during that time was able to join such a cable with many unions of devices.

Probably it’s the spacial character which is so different than some cables, where there is a slight dryness of bass with the Encore, where other cables seem to add more warmth to that single area. Still any bass dryness is fully overcome by the simple grand stage, making the bass of little or no real consequence. What we are experiencing is broad positioning of images holding tone and timbre into a kind of reality found. Bigger than expected and more emotionally moving due to size here. Funny too, as I don’t want to call this staging warm, where other cables use warmth in conjunction with staging, here there is more neutrality held with-in the brightness of the Encore. Of course many cables are too bright to use with the Encore, but here there is a form of smooth yet clear personality still holding note-weight and presence. Hearing instruments as almost for the first time, found newly separated and existing in a pure musical form, held as precious, like new found belongings? I could go on and on, but enough with this style of poetry in sound, we have other IEMs to test and new findings to discover, but I’m not sure this place here we have entered with the Encore will be found ever again…………..and I don’t want to leave. More tears……………………But if you were to ask me if the ISN GC4 has a color, I would say no, we are as close to what seems like neutral clarity in this situation, bringing the regular aspects of the Encore into a more forward statement of real. It’s this realness that has me shaking-my-head in amazement!

Ahh, you never thought cable reviews could be emotional, but they are, in fact it is the emotion is what we are all here for, to make a connection and bring meaning to the soul.


The Kiwi ears Orchestra Lite IEM with ISN GC4 Cable:
Once I started to figure out what the ISN GC4 was about I started to guess the possibilities, as far as midrange was concerned. Meaning if the midrange was expanded and separated, what would happen to IEMs that were in need of a slight opening-up of the midrange function? This could sound confusing at the start because most would think, hay…..the Orchestra Lite is already midrange centered, so what could the ISN GC4 do in the end? What the GC4 does is add spatialization to itemize the Kiwi ears Orchestra Lite’s slight mid-congestion. Yep, just what the Doctor ordered! So we are finding the Lite’s easygoing nature as a surprisingly good match for the qualities the GC4 brings to the table as a thorough improvement over the included cable. Though keep track that the $179.00 GC4 price is almost the $249.00 Lite’s price by itself.

The question is the ISN GC4 the very best cable for the Orchestra Lite? And…….I would have to say it’s the best cable I have ever used with the Orchestra Lite.

Let me explain why here. The Orchestra is incredibly even and correct in replay. The Orchestra centers on midrange tone, yet the bass actually benefits with this GC4 personality. Why? The bass is actually cleaned up slightly. But somehow there is both balance now and better imaging. It’s the imaging that makes and takes the Orchestra as an IEM to a whole new level. And if you are reading this now, and the Orchestra Lite is the most expensive IEM you own, you can rest assured the GC4 is a spectacular investment which goes ahead to maximize the Orchestra’s ideas in sound replay! Vocals were maybe slightly more forward with the included cable where there is an organic thickening taking place due to the copper and gold. This thickening somehow rests in better vocal relief into the perception of stage due to separation. As found before the Orchestra Lite is incredibly balanced, and now remains incredibly balanced. Yet the results here are that any vibrancy the Orchestra has had has been ever-so-slightly smoothed out. Still due to the stage being now what it is and the clarity at hand, such vibrancy is still one of the Orchestra’s main features and held intact.

When Dsnuts suggested the GC4 is at its best when joined to a detailed IEM, I would wager the Orchestra’s detail wasn’t exactly what he had in mind……..yet the Orchestra didn’t exist when Dsnuts wrote his review. Yet it is exactly what is happening in that the GC4 is making the Orchestra totally optimized, partly how the GC4 is maximizing the detail present in playback. Bass is more separated as well as the highs are more distanced from the stage and vivid, even though slightly rolled-off, like they always are with this beautiful signature. The Orchestra is fully brought about into focus from before being slightly a cluttered and confused affair, anyone who owns the Orchestra totally knows what I’m taking about here. So just imagine 8 BAs a side all firing-off, and corralling their intrinsic nature into an organization, and that is what we are perceiving.


The Fearless Audio S6 Rui IEM and ISN GC4 Cable:
Coming out in early 2019, it is an IEM from a lifetime ago in IEM years. Yet priced at $389.00, it’s quite the display of sonics and a value, then and now. To be truthful I have held the S6 Rui in both good and bad descriptions. One, due to its resolution and separation I have actually found it quite good overall, yet at times the midrange was ever so slightly too forward. So what do we do here? Yep, you guessed it, the perfect candidate for what the ISN GC4 brings to the table…..perfect.

I mean by now you have to be versed in what I’m up-to? Yep, so far we are auditioning mid-focused all BA IEMs. So far……….and there is good reason for this, the ever so slight warming-up of such sound replay devices, the character enhancement, the synergy. So even though a blast from the past, the S6 Rui is still perfectly suited for what we are looking to achieve. And while the Encore has a tinge of BA timbre, now what we are hearing is by far the most BA timbre heard so far today. Is that a bad thing, well it simply is what is is………though it may be one reason why the Fearless Audio S6 isn’t talked about as much today? Still even though taking that slightly metallic timbre down a notch, it’s still there, plane as day. BA timbre is funny as it’s not always (totally) noticeable, at times more and with some music more than others. But to concentrate on the positives here, the separation is profound. The clarity is real and totally identifiable. This is a balance of attributes, as when the detail and involvement is so good, it starts to replace any nitpicking on the timbre front. And once again much the same as with the Orchestra, the benefits are real life. Though I wonder how cables like the Obsidian may be more inline with our attempts at musicality? Maybe it really depends on your thresholds to treble and forward midranges, and the ability to tolerate such attributes? What I mean is the talk of gold and copper here could be misleading if you think any sort of attenuation of tone would take place…….that is why I look at this cable as adding a form of technicalities yet leaving the tone neutral. All and all at the end of the day the Fearless Audio S6 Rui is still what is is (as far as tonal balance) yet with a special widow of separation, a blacker background and a wider stage than usual.


The 7Hz Salnotes Zero IEM with the ISN GC4 Cable:
Why on earth would I join a $19.99 (originally priced) IEM to a $179.00 audiophile cable? To get benefits silly? Ok, Ok I may be slightly crazy, but I’m not insane. This totally works, and better than just works, it’s marvelous. After the Fearless Audio S6 Rui, it’s refreshing to hear this natural timbre that a single (full-range) DD can do. But more than that everything is optimal and simply really, really good.

Is this real “ear-candy”, I think it is?

The benefits here revolve around the GC4 maximizing the stage to bring about a style of separation and intrigue. Come-on $19.99 intrigue? Yep, it is what it is, intrigue. While guessing that Zero is desperate for what the Sony 1Z and GC4 bring to it………… almost never ending relaxed fluidity and wild relaxed formation of musical tones……..also enhancing any plus attributes on hand. But of course it is the stage that is the coolest thing. That and of course the timbre goings on here. Deep fascination into sound, call me easy, I’m game however good sound can be obtained and it is here. You would think the bass would get a treatment, but it’s fine? Somehow even deeper than I remember? This is exactly what has me spellbound? Again I found special midrange and took that opportunity to ask the GC4 for improvement, and improvement it did, more so than you could ever guess! Whatever the 7Hz is known for out there, it’s more now, more than ever dreamed possible? Going down as an example of perfectly smooth yet totally timbrall and involving? Even the highs are seemingly brought forth, I’ll stop now and try to regain any credibility I may have lost. Still this is the perfect example of placing IEMs into a friends ears and simply showing them what a set-up sounds like, then drop the bomb in that the price of the IEMs is only $19.99………just to see their expression, classic! Probably the most amazing thing is how the Zero is able to parley the same sonic attributes in a lesser extent, though basically in many of the same ways as the more expensive and more capable examples here. Also though it should be noted the Zero is not exactly dark but a form a neutral with a short shift into which a treble (recession) is found as placement. It’s the Zero’s midrange (and mature timbre) that expanded out and became of value! :)


The Penon Globe IEM with the ISN GC4 Cable:
While every Penon does’t work the the ISN GC4, many do. And here I will try and understand as to where our Globe progress is obtained? BAs, maybe? Interesting too as the Globe is our very first Hybrid in use today. A 3 driver 1DD X2BA affair which comes in at $329.00. Smoother than the S6 Rui ever dreamed of being, and while not the most detailed or technical, the detail and technicalities are exactly what the GC4 brings as an improvement over the stock cable. The first most noticeable thing is staging in that imaging just appears wider and bigger in size. And there is a low-end quality that the Golbe was simply asking for improvement in. Kind of cleaning-up the pace while at the same time a slight forward positioning of vocals, though this rearrangement may in fact be only from the low-end? These changes are real and notable while still leaving the overall demeanor the same, so in many ways the sound is not colored in anyway. Much of this may have something to do with the midrange as the Penon Serial and the ISN EST50 were a no-go with the GC4 cable? Literally the GC4 didn’t emphasize the vocal range present with the Serial or EST50 making them slightly lackluster and pushing the vocals slightly backwards in presence. Where here vocals were big and somewhat forward in a smooth yet slightly more accessible way interacting with the GC4 to bring about a form of almost perfection. Yep, this combination is a keeper, especially how sculpted and better defined the bass has become. So lets add this up, better deeper black background, better more defined bass, bigger soundstage (especially) width, but forward and back got improvement too and finally clarity, clarity found in vocals as well as anything in that area, which is wild as the Serial or EST50 didn’t access such changes?


The Penon Serial and ISN EST50 with the ISN GC4 Cable:
These results are by far just as remarkable as the positive outcomes of todays testing. As we delve into more and more IEMs the basic personality of the cable emerges, for better or worse. As it turns out the EST50 was only slightly better than the Serial in regards to acceptable playback, still both get the axe in recommendations with the GC4 cable. Why? The simple trait of dark IEMs being a no-go. Still with the Globe being so totally great, it is surprising none-the-less. So amazing that I tried the Serial and EST50 on 4 different occasions, just to make sure what was up. Each time the vocal playback seemed to fall back into the background seemingly lifeless and without luster? I don’t need to reiterate further.


The Knowlage Zenith (KZ) AS16 PRO with the ISN GC4 Cable:
Possibly a strange joining-up, maybe not? While the 8BA a side, $56.00 a pair, KZ may not be of the pedigree to understand the ramifications of such a cable blessing, it does respond. And if you are wondering why I chose it, well midrange BA sensibilities and………….well midrange sensibilities, that’s all. Along with the curiosity of just how much lipstick we can put on this pig? All the talk about the wrong impedance 23.5Ω, whatever, I don’t care this is great none the less. And…….even better with the GC4 cable. You know why? Because this isn’t your everyday 8BA a side pedestrian IEM, no it is not. Also this replay may just be the best I have ever heard it, you know more of the same as listed above, the bigger stage, the clarity………the AS16 PRO came alive…I have no other words to describe it. Simply involving and fun, while 100% of the overall sound is still found, the increased technicalities made this $56.00 dollar IEM sound like so much more money, ridiculously more money?


The Penon Volt IEM and ISN GC4 Cable:
It’s no surprise that this combo has gotten the most ear-time. The Volt is new as well as merging sonically with what the GC4 is doing. But there is another factor at play here. The fact that the Volt is friendly, merging and dancing with anyone in the room. Yep, the Volt simply gets along with most. But what else has been a theme here today? The midrange that’s what has been happening. So it goes with-out saying that such midrange lovelies would take our heart by force. Well, not actually by force, as the Volt doesn’t do anything forceful. There is a passive smoothness that starts to engage its play in every aspect of the Volt/GC4 cable. Where with the Fearless S6 Rui we were walking (and often over) that line into intensity, now we are gloriously back home. Back to where music comes flowing and relaxed, being truer to itself and quite possibly truer to how it was intended from the start? And if you already have the Volt and wondering if the GC4 could be the very best marriage I will try to describe what is going on? Of course you already know about the stage and clean bass, that goes without saying. But where things get a little more crucial is with the vocals…………as we already saw how vocals don’t seem to workout with the ISN EST50 or the Serial. Yet here the vocals are above water, not as bright or as forward as I’ve heard the Volt to display, yet this does get my recommendation. But it’s a slightly smoother rendition of vocals, yet not bad, not bad at all. The stage finds itself very wide and filled with small extra details that show-up, seemly unearthed? And the bass, well that too finds itself sitting slightly clearer than many cables due to a blackness of background. While the GC4 is Yin to the Totems Yang, we find an amusingly different affair, and not to be ever criticized or disrespected as each style of playback has its merits. It is just the Totem is more filled out and realistic, yet here we find a slightly tailored event, still showcasing beauty and romance. With the GC4 there is still bountiful synergy with the Volt, as it can be looked at as definite success in tone. The other side feature is the fact that the Totem is big and thick physically, where the GC4 finds itself of the thinner cable make-ups. But while the Volt is showcasing note-weight with the GC4, it’s still not all the note-weight of the Totem, as nothing is that in my history. Nothing has the note-weight of the Totem. Yet probably the greatest part of this GC4 union is the sound of completeness……yes, everything is here in playback, and not a thing is missing, even though slightly different than some cables in playback.


The ISN GC4 shows itself as one exotic animal. A rare breed, one of distinct charms and magic. While often replaying the same characteristics with a multitude of sources and IEMs, there are those few the GC4 takes critical offense to. Those few are simply not conforming to the ISN GC4’s way of being. While the benefits of stage, bass resolution and spacial magic are widely sought after, there are a few IEMs that don’t conform to the GC4’s tone antics and don’t react well to the richness on offer. Still widely skillful at play, the GC4 knows what’s up 100% of the time. While offering a form of almost neutral, the GC4 is more about improved technicalities, in fact those technical improvements flow into any IEM you chose to mate the GC4 with. It’s the tone in the upper mids that upon rare occasion, we have issues with. Now just remember that it’s not all the GC4’s fault, those traits were there (to an extent) beforehand with the IEM! Somehow doing its work the GC4 happened to showcase them, and with such clarity and transparency left those traits to be seen. The GC4 holding gold as a thickening agent and copper as its warmth, the GC4 holds a wonderful truth to its character, allowing reality to be heard clear as can be. In some instances this transparency becomes uncanny as often truth can become. Holding a total response character leaving nothing out, or wanting anything more. Such goings-on with increasing size and separation with-in the stage can do that at times, being what can be perceived as (the illusion) of perfect. Such space creates pace for the musical information to have room, and to become alive. While the GC4 is expensive there is a quality about it that makes it a necessity, just the fact that no other cable performs exactly this same way under the same environment. Due to such a demeanor I was charmed, charmed into whatever the GC4 could do, and even put-up with what it couldn’t, as love is blind that way. I have tried to give examples of success and a few IEMs that were slightly less than. Typically darker IEMs will be a challenge, yet the Penon Globe was truly amazing? My guess is it must not be that dark or dark in different places as it came alive? Even extreme budget IEMs came alive to showcase the intrinsic power the GC4 contains, now that may not be your intended purpose, yet it was there none-the-less. And the better detailed ones, the IEMs that could replay detail clearly and run with-it, well those became the best spectacle of all. As when IEM technicalities meet a technical cable, next level progress take place, and due to our neutrality becomes that much more acceptable.

The ISN GC4 Cable


I want to thank Penon Audio for the love and for the ISN GC4 Cable review sample.

These are one persons ideas and concepts, your results may vary.

Equipment Used:
Sony WM1Z Walkman DAP MrWalkman Firmware 4.4mm
Sony WM1A Walkman DAP MrWalkman Firmware 4.4mm
Sony TA-ZH1ES DAC/AMP Firmware 1.03
Electra Glide Audio Reference Glide-Reference Standard "Fatboy" Power Cord
Sony Walkman Cradle BCR-NWH10
AudioQuest Carbon USB
Shanling UA3 Dongle DAC/Amplifier 4.4mm
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Well, I have studied that place since it open in 2013. Well, there is still a realistic look where the products are not glorified at all, and they look just as they are.

Yes, your photos do their products justice.

And since I bought from Penon a few times, I noticed how some of their products are not enhanced by their images, and the real product is more beautiful than shown online.

Obviously I'm only talking about aesthetics, no judgment on other characteristics (of course).

But aesthetics is very important, and can determine sales. (otherwise there would be no industrial designers, who even design machines).
Well, thank-you. It may be a balance between studio and natural light.....that would work? But like recordings of music, it’s maybe difficult to do exactly. Yes, I can imagine getting the products in real life and becoming amazed at how much better they look. Lol


Headphoneus Supremus
Pros: Light weight. Premium build with higher end crystal copper plated in gold. Attractive and blingy. Gold flavoring adds a rich tone to your sonics. Very good match for IEMs with a good foundation of detail. Excellent imaging capabilities. Gives treble a deeper hue. Adds distinction to notes with a blacker background. Tighter defined bass notes with excellent texture.
Cons: Gold cost too much. Not a good match for warmer sounding in ears. An 8 core version would be sweet but It would probably cost double.

It is no secret ISN has been making some very nice cables and they have officially left the budget realm of cables for more exotic offerings. This being said. It seems to me they are also very aware how expensive the boutique cable can be. Considering the competition. What ISN has been doing is giving the enthusiast premium handmade cables but at a more approachable price. Their newest entry I can say is more expensive for an ISN cable but the most expensive is still their AG8 pure silver cable. The ISN GC4 comes close at a $189 RP. The GC4 stands for Gold Copper 4 cores. Naming scheme for ISN always makes a lot of sense and this newest cable is yet another brilliant addition to their cable line.

So what does gold do for sonics? We are aiming to find out. I would like to thank ISN and Penon for the review sample of the GC4. It can be purchased on the Penon web page here. The analysis of the cables are my opinions regarding the cable are based on cost, build, effect and value. Now let's find out what the GC4 is all about.

The ISN GC4 comes in their standard ISN packaging inside their rectangular box is a semi hard all black rectangular zip up case. The cable itself right away you can tell it is of a premium quality. The Ysplitter chin slider, plugs and the connectors all have a bronze/ copper color with golden rings highlighting the premium color scheme of the cables. Which happens to go along with the actual make of the cable itself. The cable cores are made up with a premium grade of crystal copper which is then plated with you guessed it. Gold. But it doesn’t stop there. Premium silver solder is used and to finish it off the plugs are plated with Rhodium. While the price is not cheap. You have to look at boutique cable offerings with similar materials and craftsmanship and then you will get a good sense of where this cable falls in line value wise.
$189 gets you a lot of cheaper cables or even a good earphone but for the folks that feel the need to upgrade that stock cable of yours. The ISN GC4 is a great option especially if you feel what this cable adds sonically will mesh with your particular IEM. Getting the right cable to earphone combination is a bit like chemistry. Goes without saying. An analytical detail enhancing silver based cable will not match well with a highly detailed IEM for example. That is asking for ear fatigue. Now adding a gold plated copper cable on a highly resolving IEM. Now we are talking about synergy.
Gold while not the best conductor for sonics, that title goes to pure silver however I found out gold adds something a bit extra that I had no idea about. The cable itself is made up with some thinner cores of gold plated copper weaved into the 4 cores. The physical look of the cables while ample is a bit on the thin side. A plus for folks that like their cable light and not so thick n weighty. Compared to something like their AG8 or CU4 cable which consists of thicker cores. The GC4 is a thinner and lighter style of cable. Cost probably had a lot to do with the physical bulk or the lack thereof. Cost aside I have to admit I was expecting a bit more physically, but you have to consider what the material here is.

Sound analysis was done connecting the GC4 with a variety of in ears including the Dunu Luna, NF audio NM2, Tansio Mirai TSMR-6, and ISN H40.

In general at the cores of the GC4 is a highly resolving pure crystal copper which in and of itself is one of the best transducers of sound. A higher end quality of copper that bodes well to inject some musicality in tunings. Then the gold plating brings a plus on that copper sound. I would like to mention copper cables are great for smoothing and adding body to detailed earphones. With the added gold there is a richness to the sonics that copper by itself does not have.
It supersizes the effects of crystal copper with an added distinction for instruments and vocals. A better sense of space with a blacker background giving better imaging to music notes. I noticed treble has better depth and roundness. Expansion of stage is done better on silver varieties of cables but the specialty of the gold plated copper seems to do an extra for the mids of your music giving it better distinction and definition more so than enhancing the treble or the bass ends. Due to the copper aspects treble is slightly smoothed out but the gold aspects seems to round out the treble a bit better than standard copper. Bass notes also seem better defined, a bit richer, better textured and gives great ability to the bass drivers.

Earphones that are more analytical/ highly resolving/ detailed or phones that have dryness to the sonics. The GC4 will add some dynamism, better imaging with an uptick in a richer tone. I noticed earphones that already have a smoother darker tone does not do as well synergistically.

First up was with NF audios NM2 earphones. These monitors are more detailed than the price would indicate so I felt maybe the GC4 could add something to the NM2. This pairing is unbelievable. The GC4 transformed the stock NM2 sound to something special. Gives the sonics better distinction from treble to bass with a blacker background, adds that touch of richness. A clear dynamic balanced tuning. The GC4 matches up so well with this earphone I am now debating to get a 2nd 2 pin GC4 to match up permanently with this earphone. As the saying goes. You can’t unhear it. This pairing will make the hairs on the back of your neck stand up. NM2 has outstanding vocal properties to the sonics but with this cable it adds a free forming airy sound with better definition over the stock cable that will make you wonder why you spent so much on earphones that don’t sound as good. So far the best synergy I have heard using the ISN GC4. That goes to this little $100 IEM, NF audios NM2. By the way if you don't know anything about this IEM here is my review of them.

2nd is the community favorite. ISN H40. GC4 is a good match for the H40s smooth tonality. A bit wider sense of stage. Spacious vocals with a bit of a richer, silkier tone to the mids. Depth seems to be better using the GC4 vs stock cable. Better sound separation and definition. Being a copper cable the GC4 adds a tighter punch to the bass end and brings an absolute ability to the bass. Treble is portrayed in a rounder slightly darker characteristic. If you have never heard a dark treble effect. It is my favorite type of treble portrayal due to the uniqueness in tone to the treble.
TSMR-6 is a highly resolving Tansio Mirai earphone with an analytical nature of the tuning. High levels of detail with excellent imaging. The ISN GC4 matches well with this all BA earphone with added depth a better sense of note weight. That richer tone comes into play giving an injection of musicality to the base sonics of the TSMR-6 sound. These are the type of earphones that ends up matching well with the ISN GC4. While I would give the best synergy to the NF audio NM2. TSMR-6 is in 2nd spot with this matching. Treble notes sound less edgy and more cleaner actually sounding a bit more silkier. Bass has excellent presence and punch with this cable. Again adding a bit more in the way of body of sound due to the copper element. The gold gives that musical edge to many analytical tunings that brings a better sense of immersion.
Finally we get the Dunu Luna. Dunu Luna is a highly resolving dynamic flagship from Dunu. Dunu has a well balanced tuning that is more referenced in the presentation. Injecting some musicality from a gold plated copper cable is not a bad thing. This pairing is excellent and while Dunus own stock noble cable that comes with the Luna edges out the ISN GC4 as it should considering it is double the cost vs the GC4. The GC4 turned out to match up extremely well on the Luna. Here is a case where the ISN GC4 gives a slightly different take on the Luna sound signature.

The Luna has a very dimensional sound and while the stock noble cable does a great job bringing out the details and adds to the dimensional aspect by giving the Luna better fullness in presentation. The GC4 adds a touch more in the way of imaging. The slightly warmer tone of the Luna now sounds more richer in tone. Live sets sound superb due to that added weight to the mids tone. Imaging hangs right in there with the Noble cable and actually sounds just as good in that department. Treble sounds a touch smoother and bass is as detailed as it ever was. The ISN GC4 while half the cost of the Dunu Noble cable, actually makes for a good alternative with a slightly less forward sound while adding weight and distinction to notes. This is a great pairing.

In conclusion the ISN GC4 is a cable well worth owning. For enthusiasts looking for a high quality cable to pair up with your favorite in ears. If you have a highly detailed and resolving earphone and want to add a richer tone to the sonics these are very good in that regard. The ISN GC4 will not drastically change your earphone to be something different but it will add some musicality, distinction with great imaging properties. Thanks for reading and always happy listening.
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