General Information

Brand:ISN Audio
Model: H40
Driver:3 Balanaced Armature + 1 Dynamic driver
Dynamic driver : 9.2mm
3 Balanaced Armature: Custom 1 BA for middle Frequency + composite 2BA for high frequency
Impedance : 22 Ω @1khz
Sensitivity : 105 ± 3dB @1khz
Frequency response : 20-20kHz
Connector: MMCX
Plug: 3.5mm
Cable length: 1.2M
H40 GRAPH.png

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Headphoneus Supremus
Basshead eargasm
Pros: -fun lush bassy musicality
-warm and natural tonality
-thick timbre without BA artificial flavor
-big, chunky, rumbly and well define low end
-good note weight
-free of sibilance or any harshness
-good layering
-beautiful vocal and mids that aren't too recessed
-versatile basshead U shape tuning
-dark treble with some snap
-good packaging, cable and accessories
-price value
Cons: -not best bass separation-definition
-poor imaging
-lack of treble sparkle, micro details and air
-average soundstage, especially in depth
-bass would be too much for non basshead
-not the fastest bass
-source picky in term of output gain-impedance

TONALITY (basshead perspective): 8.5/10

My crush about these IEMs (1DD+3BAs) seem to never begin to be a long honey moon! is it guilty pleasure because they are near basshead? I don't think so. I prefer call it: Engaging Musicality
Because not only the bass hook me with its beefy flexible slam, but both its quantity and quality impress me since a whole DD cover the task...but this hybrid offer a cohesive warm U shape as a whole too, without this warmness produce by the bass, it wouldnt be the H40.
The timbre wouldnt have this density and softed timbre definition. When its colored-magnify naturalness, how we call this?
I tend to use lushness, or euphony, here its liquid densify euphony we can say...
Anyway, i just love those lol Fun, engaging, warm balanced basshead way and technicaly competent due to this fast BA layering that permit this eargasmic fun ride!
The real critical impressions begin by pressing ''shuffle'' of my whole musicbee catalogue....right now its ''Marty Ehrlich travelers Tales'' jazz band, bass warm the mids quite alot, they feel a bit dark yet the tone is right and note weight is there. Saxophone sound phenomenal, natural, fowards and open. Acoustic guitar have a bit of over emphasis on low harmony, lack a bit of sparkle and brilliance as expected with balanced armature. While i was praising bass for soul, R&B, electronic, rap, for jazz i would like more definition and cleaner extension, here it add warm and chunkyness to contrabass, which isn't very textured yet...i do enjoy this track...
Now Celeste singer come in, and her vocal are super fowards, lush, thick, very beautifull just, for female vocal their no doubt these are excellent, if i force myself to pick up something when she go breathy we have slight timbre texture boost that feel too much.
Now its ''Mussorgsky: The Nursery''. Piano+Soprano. Piano sound great, not the most define and texture yet every note sound full and weighty. This kind of soprano singer will go screamy with too boosted pinna gain, here its smooth yet dynamic, its very soft, no timbral imbalance like Celeste so it might be the recording (mic to near her lips for this very song).
Now its Pierre Hantai playing Scarlatti on Clavecin, as expected, its a bit too dark and lacking brilliance, crispness, airyness and natural resonance to play properly this instrument. It sound full, but not enough metallic.
Now its a String quartet. Very beautiful violin timbre and fullness with good layering, when they do pizzicato it lack a bit of bite but thats about it, its very smooth and lush yet not dark.
OK. I come out of these tracks even more impress by tone, timbre and cohesion of tuning and drivers, for a bassy IEM, these are very versatile. Might be the perfect upgrade to something like Audiosense AQ4 but i need to do proper ABing.

For those wondering why i put 8/10 for technical performance, it's because at 200$ this isn't end game for sure in term of resolution, attack speed and imaging yet the soundsignature partly explain why. These aren't technical sounding IEM at all, everthing is about bass fun, and tone and timbre colored naturalness. Its a thick sounding IEM that doesn't magnify sens of clarity yet avoid plain muddy rendering due to decent layering capacity only an hybrid can produce.

For more insight as well as a comparison against Penon Serial, Audiosense AQ4 and ISN H30, give a look at my video review here:

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Headphoneus Supremus
A Tiger About
Pros: Wide and tall soundstage
Great bass definition and authority
Does vocals with ease, even though not an ounce of Pinna Gain heat
Big sound exclusively belonging to the ISN H40
Treble and midrange have pace through dynamic contrast
Such gifts normally found in an entirely different pay-grade
Fantastic attention to build detail
Well-rounded, optimized from any source, playing any file quality or music genre
Included is the same S8 cable as the ISN Flagship TOTL
Cons: Not the last word in ultra-high treble physicality
Such a sound character should be avoided by those into linear old-school audiophile playback
It's a new day, wake-up and smell the coffee
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Remember that time you upgraded to a bigger TV? Well, that is the feeling you will get when first listening to the ISN H40 IEM. More intensity, more vibrant colors, more clarity and higher image resolution. It’s just a fact of life that technology evolves and gives you more immersion at a cheaper price. The down side you ask? ................there is none? Now is the H40 perfect? No, but way closer to perfect than you would expect for $195.00.

Let’s add this all up, shall we?
  1. Zero pinna gain heat ever......none to be found ever
  2. Big, super-big soundstage, populated with correct tone
  3. Dynamic and full-bass response that doesn’t mess with the mids
  4. Clarity and well-done treble engagement
  5. Big polished and pushed-out mids
  6. Build quality and looks that seem way above its price point
  7. The S8 cable, the same premium cable that comes with ISN’s flagship IEM
Wellcome my friends to another review. Typically the IEMs I cover are brand-new and only out-in-the-wild a week. And while new-stuff is super exciting, prior IEM fame can also be enjoyed and reiterated upon, especially when its a creation like the $195.00 ISN H40. ISN is a very successful cable manufacture, yet in December of 2019 they released their baby, a 1DD/3BA Hybrid that incorporated the ISN house sound. The ISN H40 was so popular that in July of 2021 they expounded on it with the flagship $459.00 EST50! So sit back for a second and take that all in…….ISN builds lots and lots of cables, they then get a dream to become an IEM maker and release the H40. The H40 does so good they enhance technicalities to create the EST50 with identical H40 tunning. I mean why spoil a good thing, right? Right up-front I will reveal the H40 sound is 90% of the EST50’s. For the new EST50 they kept the H40 the soundstage/frequency response the same but moved the EST50 instruments backwards to make room for added imaging/texture and timbre. Due to the H40 being such a forgiving and well-rounded performer, many have cited it as their single deserted island set. That means if they were to go off to a deserted island and could only bring one IEM, the H40 would be their choice. And I now see why, the H40 is the quintessential Hybrid, offering all those sonic extras a Hybrid brings to the table. The one thing the H40 doesn’t bring along is steely metallic-off-tone normally associated with Hybrids. That’s the excitement in a nutshell! Big and clear bass response, authoritative soundstage, and immersive involvement is what makes the H40 click!

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Upon construction of the H40 ISN introduced the ultimate form-factor feature in the one-piece build. How else can you view the silky, sexy one piece finish? It’s easy to pigeon-hole all the acrylic shells into one category. But here at $195.00, we seem to be holding somehow more in our hands? It starts with running your fingers across the finish, how the H40 is ergonomic through and through. This finish business extends to how the MMCX mount is flush, how the nozzle-end seamlessly joins the body. The way the semi-custom form has all those angles so it fits closer inside your outer-ear. The resulting external sound occlusion, the actual warm feeling of the shells in your ears………all these things, all these little things add-up. Upon a shift from tactile to visual inspection, we are now viewing how the faceplate joins the shell. Wait? There is only a single flowing object? Besides the MMCX and the nozzle-adds, there is nothing but smooth acrylic, not only is it smooth but one-piece. I mean yes, you can kinda see that a faceplate was used in studying the reflections, but eveything has been filled in and buffed-out to perfection. Such a device ultimately becomes a part of the wearer upon placement, with the semi-custom shape going to the next level to also make that happen. A single almost unnoticeable air-vent can be found centered near the top of one-side, the same place as the EST50. A single symbol, a kind of trademark/monogram sits floating in space at the center of the faceplate. Such a monogram is the only marking to exist on the H40. The removal of any right/left marker or model number goes one step further to enhance this clean singular statement of audio-art. The color looks black upon first inspection by 3 hours later you hold the H40 against something truly black and realize it’s midnight blue. The finish does not show fingerprints, even though you think it would.

Technical Specifications:

  • Driver Configuration : 3 x Balanced Armature + 1 x 9.2mm Diameter Dynamic Driver
  • Impedance : 22 Ω @1kHz
  • Sensitivity : 105 ± 3dB @1khz
  • Frequency response : 20-20kHz
  • Connector : MMCX (Micro Miniature Coaxial)
  • Plug : available in 3.5mm TRS, 2.5mm TRRS or 4.4mm TRRRS variants
  • Cable length : 1.2M

Being an example of the ultimate Hybrid, the H40 offers a 9.2mm Dynamic Driver for the lows. Custom 1 BA for middle frequency and composite 2BA for high frequency.


The S8 cable:
The H40 is fitted with the exact same S8 cable as the flagship ISN, the EST50. With both IEMs sporting the identical FR, I didn’t do too much cable rolling……..didn’t need to. It just so happens the S8 became a legendary cable in the EST50 cable rolling and amplifier tests. Such a cable is introduced by ISN as a substantiated cable manufacture, so why wouldn’t they included a “high-performer” as stock with their very first IEM? In such EST50 tests I found the cable to be well-rounded and spacial............being a hybrid mixture of copper and silver. The cable introduced a brighter more energetic treble into the EST50 from solid OCC experiences. Such a cable also becomes lovable due to its physical softness and pliability. The MMCX fasteners held-up really well with my photographic four (4) cable changes. I did use the MMCX removal tool each time, but upon joining the cable back it was super-firm in placement and offered only rotation when you asked for it. Such a cable also follows a nice theme using four pieces of gold and black hardware. One for the MMCX, one for the cable sider, one for the cable joiner and one for the plug. When you order the ISN H40 be sure and designate the style of plug your into, being 4.4mm, 3.5mm or 2.5mm.

S8 Cable:
  • High purity makes the cable extremely soft, providing the comfort of wearing,
  • Gold-plated plug is more beautiful and durable, using insulation treatment technology.
  • Natural and transparent sound, delicate and smooth; lift medium and high frequency, strengthen high frequency extension

  • Model: S8
  • Material: Single Crystal Copper Sliver-plated
  • Number of cores: 8 shares, single share is 19 cores, a total of 8 × 19.
  • Connector: 2pin 0.78mm
  • Plug: 3.5mm audio/4.4mm/2.5mm balanced gold-plated plug
  • Cable length: 1.2M

Even-though priced at $32.50, and the second lowest priced cable in the ISN line-up, I still view the S8 cable as the Toyota Camry of cables. Truthfully, I don’t view/judge cables by price, only performance. Coming into the opportunity to review ISN products, I wasn’t sure what to expect from their included cables, even though before making IEMs they existed as only a cable builder? While other cables I used did offer other tonal and positioning discoveries, the major find was simply how good of a cable the S8 ultimately was/is. Taking the H40 and S8 to my reference (TA) rig left nothing to be desired, showing great timbre, pace, positioning and tonal character. Much like the rest of this package, ISN is offering a lot for a little money spent.


The ISN Company:
ISN current cable offerings:

Silver-Plated IEM Cables: S4, S8, AG8, S16 and one Type-C Silver Plated USB Cable
Copper IEM Cables: C4, CU4, C16
Mixed Cables IEM Cables: Solar, G4, GS4, SC4, H8, H16
Gold-Plated IEM Cables: GC4, GD4
Pure-Silver IEM Cables: AG8

ISN Ear-buds:
Rambo 2

H50 10mm Composite DD (bass) 2 BA (mids) 2 BA (highs) $295.00
H40 9.2 DD (bass) 1 custom BA (mids) 1 composite 2BA (highs) $195.00
D02 10mm DD $79.00
D10 9mm DD $169.00
EST50 1 Knowles BA (highs), 1 Sonion BA (mids), 10mm DD (bass), 2 Sonion ESTs (ultra-highs) $459.00

Strangely, even-though making all this complicated stuff, ISN describe themselves only with one sentence.

“We are a wire production and R&D factory.”
ISN found a niche making “sonic-reactive” cables. Such cables infuse genuine character into your IEMs, though at a cost-effective price ranging from $32 to $400 dollars. Making IEMs was the natural next step to take. Offering 5 inner ear monitors, and 2 earbuds, they offer a complete selection. With 17 total cables (each with varying degrees of their own character) they really have ways to enhance or change the sonic profile of your listening experience. Matching an IEM to a cable is in effect tailoring the sound, even at times adding correction. At times this tailoring is simply a way to “EQ” subtle changes to suit the listener. Each metal offers a character reactive to construction with some cables having more copper and other more silver it seems. While I’m under the impression amplifier character does more to change and boost fidelity, cables can still offer a way to fine-tune the listening experience, especially if you already are using you favorite amp. ISN is finding true audio changes and passing those changes from the research and development area directly to the public. My experience is limited in that I have only one ISN cable and two ISN IEMs, though in side-by-side testing, both the cable qualities and IEM qualities have been substantial. Only after investigation and comparisons (first hand) do I truly understand the efforts put forth, because you don’t know what you don’t know…..till you know. This is why reading reviews only goes so far as to plant the seed, with the rest of the effort up to you.

The box opening experience:
For the price point everything included is exactly right. 12 sets of ear-tips go along way to enable a limited struggle to finding art-tight fit. The N8 cable is sexy-as-heck. The shirt-clip, tool and carrying case are a nice touch.

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The H40 and ISN:
There has always been a slight discrepancy between Chinese made IEMs (with their tuning) and the Western Tuning. Obviously there are all styles of tuning, but speculation has it that the Chinese simply hear music different? I am not about to tackle such questions……but I do know one thing………….I know a Western Tuning when I hear it. And guess what? The ISN H40 sounds like a Western IEM, in fact it is the most Western Tuning I have ever heard from China. So that one thing makes the H40 a novelty. Of course I will get to exactly how it sounds, and also do comparisons, but this arial view of the sound signature serves of purpose.

I like the ISN H40. I probably wouldn’t change a thing.

The H40 can best be described as big sound, big bass, big soundstage and big authority for $195.00. It’s the quintessential Hybrid sound, with one 9.2mm dynamic driver, one balanced armature for the midrange, and a joined composite duel driver for the highs. What Hybrid sound does is offer a specialized style of separation, with the dynamic making bass noises, and the three balanced armature making midrange and treble noises. Because balanced armatures can pinpoint image displays, we are offered such separation of ingredients. It’s true that Hybrids may not offer the cohesiveness of Planar IEM, or the oneness of single full-range driver IEMs. Yet the people who are super into this style of playback pay for Hybrids and know the sound they are getting. Hybrid technology is still advancing forward, with many new examples of Hybrids just this year alone.

I was sent the flagship EST50 and the legend, the H40 for review. The reason they showed-up together was because they are the introduction to the ISN house sound. That’s right, the H40 is the entire genesis of the ISN sound. They came about a self-realization, a teen-identity discovery of exactly what they would be in 2019. Such a solidification that they then carried the same exact tune over into the company flagship in November of 2021. So I’m not sure you could find any better way to give the H40 a tribute, than to make your Flagship/TOTL $459.00 a splitting (frequency range) image of it? They did such a unique gesture due to ISN finding their sonic identity in the H40. And if your on the edge of your seat wondering what improvements can be found, I’ll tell you. They took the forwardness of the sound elements and moved them to the back of the room. What then took place was a kind of forward imaging that found improved instrument texture, and timbre. So the EST50 literally sounds exactly the same.........but brings detail and technicalities into the mix. That’s it, well there is a slight physical-size difference too, with the H40 being a hair smaller. The reason I’m so excited to do this review is there truly is not all that much difference between the two IEMs. It’s uncanny how close to the same they are. In fact it really threw me for a loop in the process of comparing them. No one told me ISN put the two on a test bench and recreated the legend.........just adding more make-up and lipstick. Now I could go all day trying to explain the differences between the two, but that really wouldn’t get us anywhere. You can read my EST50 review here.

Such a review almost goes overboard to explain what style of IEM the EST50 is. And there would be nothing wrong with shifting gears and just getting the EST50, as there is nothing the H40 can do that the EST50 can’t do. Still there is more of a market for $195 IEMs, and even more of a market for what the H40 does for $195.00.

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Sound generalizations:
Probably the best part is how the separations take place. In that regard they really are the quintessential Hybrid. Everything has it’s own zone in the soundstage. Where it’s not the last word in detail, but somehow everything is jigsawed together, as nothing is left out. Even old-inferior recordings get the double slam of both soundstage expansion and warmth which sonically excavates them from the past. The H40 has that same uncanny way of doing pace, rhythm pushing the song along. So even if it’s not the last word in detail, it offers tight-pace and forwardness in bounce that seems to make it simply entertaining none the less. I’m not going to say it’s making music sound live, but it is going slightly that direction. Where it tree-tops areas, it’s not sloppy, but not getting down to the base of the forrest. This whole tree topping thing isn’t bad, it’s just taking what it needs, and leaving some of the detail out.........just not using it. It was the mission of the EST50 to try and set everything slightly back so that a level of detail could be introduced. Still the midrange has the great second soundstage where things like rhythm guitars flourish and add additional pace on-top of pace. There can be a low thrusting rhythm guitar that’s ultimately connected to the bass and drums.

It’s this back and fourth movement that makes you feel the music and want to play air-guitar if no-one is looking. If that’s not a reason to get an IEM, I don’t know what is? Every song sounds good. You know you have won this game when you go to only hear one song, and you play every song on the album till it ends. Such an acceptable tone that we need not be picky or prudish what we feed the H40, it eats anything.


The testing takes place with the use of 50 or more individual musical examples. With-in these samples I am attempting to ascertain the presence of all the qualities described in this review. But to clarify and communicate concepts, I always choose a relatively small group of recordings. This occurs for two reasons, one they are good recordings, allowing the full-spectrum of musical playback process to take place. And two, I know them the best after using such examples for years and years. Dark Side of the Moog VII.......I obtained when it was a new release in 1998.

Pete Namlook & K. Schulze: The Dark Side Of The Moog VII
44.1 kHz - 16 bit

Studio Album, released in 1998

Songs / Tracks Listing
1. Obscured By Klaus (Part I) (4:59)
2. Obscured By Klaus (Part II) (7:22)
3. Obscured By Klaus (Part III) (18:58)
4. Obscured By Klaus (Part IV) (6:34)
5. Obscured By Klaus (Part V) (3:42)
6. Obscured By Klaus (Part VI) (8:09)

Total time 49:44
Line-up / Musicians
- Klaus Schulze / composer & performer
- Pete Namlook / composer, performer & producer

- Bill Laswell / composer & performer (3)

Note: The actual instrumentation was not available at this moment
Releases information
Seventh of a series of collaborations under the common title "The Dark Side of the Moog"

CD Fax +49-69/450464- PK 08/143 (1998, Germany) Limited edition
CD Ambient World- aw 032 (2004, Germany)


Here we are greeted with an Moog synth with another synth dueling it out. Both instruments trading rhythm-splashes until 34 seconds.....when an organ-wash style synth becomes a new backdrop. The very first Moog is continuous and almost without variation, yet it is also the lowest bass component of the song. It’s row-row-row your boat, done on synths. Each element is loosely connected, yet apart. Finally at 3 minutes 24 seconds the synchronization of syncopated synths are added. Then the very first Moog comes to the forefront and takes complete control of the song. The first syncopations were a decoy to the surprise. At 5 minutes 40 seconds a feature synth marks the advancement in the piece! The feature synth a signpost to show all the tracks have been added. Next we have a final add right before tracks start to be taken back away. The reason this works is the first deepest bass notes were shown well and positioned correctly. As the song progressed there are slight adds of almost sound effects that take on a visceral and unexplainable deep meaning tonality. They are fast and fast changing yet the H40 does them and they get out of the way as fast as they arrived. Such musical elements are in-fact momentary and not connected to the song structure. This is the epitome of robots talking at the end. When in fact, if you go to the start once more it is also conversion between synths. Upon first listening you perceive the song structure different, only spellbound by the tone, not realizing that a style of (performer) dialogue is in-fact taking place!

I can’t help but try and understand the songs make-up? Yet when I give up on that, the ISN H40 comforts me and lets me know it’s just musical tones and nothing more.

Somehow we are brought back to the primal elements and relinquish any cerebral strongholds in trying to intellectualize the experience. It’s this giving-up that sets us free to enjoy the music. At one with the tones, they are now abstract and undocumented. There is no way this music can exist on paper. Of course this is two individuals playing-off each other. An intertwining and constantly changing Moog-freak-out taking us to new imaginary places.

Of the two ISN IEMs I have tried, they really seem to like the Sony TA desktop. It may have something to do with the lower midrange or the imaging? Whatever it is it’s noticeable. First-off instruments have better separation, now you might remember I started off elaborating about the wide soundstage and separation at the start. Such deep control makes this all simply fun, the deep control of the bass in the start of The Dark Side Of The Moog VII. Synthetic styles of music isn’t the only thing the H40 is good at, but the vividness and tactile-ness make for quite an evening. The layers of fun are just that. More separation and space between notes than I could have ever guessed beforehand. I know that I’m over emphasizing this one feature, except that is the one feature that stands out. It’s very, very well done separation that makes space for 100% of the rest to breath and gain life. Such elements may be the key to this style of music too? Where there is nothing more than synthesis taking place and floating in space. Everything is directly recorded into the mixing desk, thus nothing lost, nothing to gain a room response. We are left with a pureness of sorts. And the H40 honesty replays that’s connected to the sounds. Such a connection makes us involved and witnessing understanding of the music. The trick here is there is never any pinna heat, yet the midrange seems complete and correct? The EST50 obviously did this better, but the difference is small. It’s the diminishing returns where the H40 is providing 90% of the same sound. It’s just that the EST50 is filling in the H40 sketchbook for it. Like the better equipped EST50 looking over its shoulder to show a next level of detail that the H40 doesn’t know how to approach. Remember they are tuned exactly the same, which means most all of the music sounds the same. I have never had two identical tunes to compare with separate technicalities. And yes, to quantify the difference in one single word, that word would be EST50 smoothness. Still this ends being a selling point for the H40 as you can achieve 90% of what the EST50 does for way less money. If that sounds like a bargain to you, it’s because it is a bargain. The H40 didn’t get the memo that it wasn’t supposed to be able to produce this level of separation and this level of bass. The third factor is that the H40 has the perfect tune. Perfect is a word I almost never use, but in this single case it fits. The additional perfection occurs because this (particular) music doesn’t have real-life musical counterparts. Meaning we can’t judge the timbre because electronic sounds vary more, and don’t have any of the characteristics we judge drums or violins by. No wood resonance or sonic-forms of decay, timbre or actual instrument tone. They are pure electric sound-waves traveling from instrument to tape, so to speak. They are bypassing the recording room reflections and bestowed characteristics from being “in-the-air”. Pure tone. If this sounds fantastic to you, it is because it IS.

$195.00 IEMs that have the ability to scale up with better equipment.

At first I wasn’t that impressed by their scalability performance, but I kept listening and it started to reveal itself. Then later I switched back again to the EST50 to double check my findings. Both using the exact same equipment, the H40 has the same S8 cable, though the EST50 has 2 pin, where the H40 is MMCX. Such equipment equalization is down to using the DUNU wide-bore tips on both IEMs. And strangely the blue tip color is an exact match to the album cover! What more do you want here? :) A matching product box maybe?

At 25 minutes 36 seconds there is this bass texture event which is (in-fact) simply reintroducing the same bass, maybe louder? Such event acts reminder that the H40 is ultimately in its element, right at home. Remember too, this style of music is the original headphone music. There was a time in the 1970s when headphones brought about a new way to hear imaging and soundstage, a distant playback from table-top radio. Such attributes are the very reason we even are interested in the H40 in the first place. To create a musical environment apart from daily life, where we can experience the drama and intensity of music like this. Due to the sounds coming from not space (in-reality) but headspace, those sounds come-off more direct.

Cat Stevens
Teaser and the Firecat
96 kHz - 24 bit (needle drop)


Ahh.......more blue and orange, I choose my review music by album cover colors not music. :)


Quote: Cat Stevens on Moonshadow
"I was on a holiday in Spain. I was a kid from the West End [of London] – bright lights, et cetera. I never got to see the moon on its own in the dark, there were always streetlamps. So there I was on the edge of the water on a beautiful night with the moon glowing, and suddenly I looked down and saw my shadow. I thought that was so cool, I'd never seen it before."

It’s really important to include this single song here. As it turns out the H40 does vocals really well. While it is known for having extra bass and a nice treble to balance the bass out, in fact the whole response comes off super well-balanced, if you can deal with the bass additive? Some one asked me if the EST50 was an allrounder or not. I said it was an all-rounder except since I’m not really a vocal (only) listener, I simply didn’t know how they would do with singularly vocal music. Now while Cat Stevens is considered “Singer Songwriter” it falls into the vocal-centric territory. So due to the EST50 and H40 sharing the same basic frequency response, they can be judged accordingly. Such a gift of inner-ear-monitor tuning makes all this happen as almost by magic. As you and I know, so many Chinese made IEMs can exploit that Pinna Gain area to almost miscalculate what is needed for vocal frequencies. They will do vocals well, except they went and tuned those to basically shoot way past the needed vocal frequency. This can result in one of three issues/concepts for the listener. One, they have a high-tolerance for such shenanigans, Two, they simply have to turn it down or three, that playback is intolerable. Really this is a big deal, but it should also be noted that this effect is not an off-on phenomena. There can be a walking in to the threshold, where the Pinna Gain heat is only present in a few areas, or of course the way past trouble effect..............where replay simply becomes a no-go, at almost any volume used.

Interestingly here I am able to listen at any volume. While switching to the EST50 I’m shown loud areas in the recording which are recording volume peak red-line-areas.........causing tape-compression. The tape-compression recording is there with the H40, just not heard as much. This is one of those rare instances where less detail is better.

The H40 is already popular. It is the ultimate deserted island IEM in that it truly does all style of music and file quality..........not only with ease, it does them with passion and ability. The only thing I will add is there are maybe abilities of vocal-centric IEMs to reach a slightly better area of separation. The rendition of vocals could stand out to become simply better? To tell you the truth, I’m not really schooled in such abilities or character… I can’t say. But this singer songwriter sub-genre was perfect? Cat Stevens voice has a woody darkness that is unmistakable, while he also does a vocal range, it’s not as often heard. It is his singular sound he is famous for and the H40 gets 100% of the tone across. Even the nice extra guitar-harmonics were found to sound completely natural and pure. Despite the ISN H40 using BA drivers, it is one of those times I can’t really seem to hear any BA off-timbre of metallic character?

The Golden Retriever:
Such nomenclature goes to describe my over-generalization of IEMs. I place all IEMs reviewed as of late in one of three categories Bad, Finicky or Golden Retriever. The H40 gains the Golden Retriever mark as it’s great from any source, obviously getting a larger soundstage and better dynamics from a better source. The second Golden Retriever trait is to be able to play all sound files, which it does. Meaning thin or dated old recordings still sound good, and any genre sounds good. And finally the H40 is open and offers a wide range of experimentation from cables and ear-tips. Such leeway goes miles to offer you both generally good sound and the opportunity to slightly change the sound. Meaning tips or cables are not used in this case to correct a problem, but only used as a way to achieve a wanted variation of playback. So to summarize, Golden Retrievers offer an easy going complement to any DAP/Amp, any use of cable or ear-tip. And finally…….play all sorts of music well, both any genre, or any level of quality.



I personally maybe get the most out of side-by-side comparisons. Such a set of tests ultimately showcases which values are important and why. At times obviously this set of differences between two IEMs can be subjective, but at times the contrast is just so prominent and real, there is no other way…………than to call-it like it is. While every IEM has a wide range of abilities, I’m still trying to generalize and find truth. There are far greater differences than what is tackled in our comparisons today. The best way to find value is to realize the comparisons are truly only key points. Each comparison has its own prior review (listed) so further details can be obtained. The fact that I can try and describe a character all day long, but put that character along side another IEM that you have heard and communication takes place. Still the use of amplification, cables and ear-tips can surprisingly go to enhance or diminish a character trait…….the H40 was somewhat resilient to any changes, marking the IEM as a Golden Retriever.



This $189.00 IEM ends-up predating the release of the ISN H40, the DM6 was released in September of 2018. Many might argue that its age means it’s not relevant to our discussion today. I believe its relevance still holds simply due to its wide-range popularity at the time. Though keys elements are the H40 major sound improvement at the same price. It’s hard to imagine the H40 arriving a year later but doing everything so much better. At times I just have to laugh to myself. No, I’m not crazy, simply in awe of how much better an IEM that came a year later at almost the exact same price-point can be. It may have actually be some sort of paradigm shift in the industry right around that time? As this is one example of a giant leap forward in terms of real-ness. The DM6 is offering a tone that is less natural, but even if you forget all that the H40 is obviously deeper in the bass department. The H40 is boasting better imaging along with more articulated examples farther out into the soundstage. This thing of buzzy BGVP DM6 (swarm-of-bees) sound rendition.............that’s the DM6 simply doing all it can, yet getting fully defeated at its own game! There is absolutely nothing the DM6 does better, sorry, nothing! The over-all look and feel of the H40 in your hands also tells a tale of quality....the metal-tipped nozzles on the H40, in comparison to the simple beveled edge on the DM6. I hate to say it but even the build materials/fit/finish of the H40 give the impressions of a much better and thoughtful product. I could continue, but I will leave it be. I even have the solid-black DM6, and you would think they (at least) would have the same look and feel, but no.

The black BGVP DM6:

2EST+2BA+1DD Hybrid:


This is the full comparison from the EST50 review. I just wrote the review a week ago and these thoughts hold true now, so why not include them?
First off I would like to say the H40 deceptively does a lot with a little. Meaning to better it they had to take a step back from the H40s more forward and in-your-face presentation. Such a character can often be tricky in these side-by-sides as forwardness isn’t always better, but just like fast-food can offer that instant gratification only to have you maybe wanting more as time passes. The H40 is a hair more efficient. First noticeable is how the EST50 effortlessly fills in the sketch work done prior with the H40. Such examples of playback start with simple elements in the soundstage sitting farther away with the EST50. As with prior expectation bias, I thought maybe the EST50 bass would be way louder or stronger or something different? When in-fact what takes place is more detail and better controlled/realistic bass-timbre. Such textures exist to be heard somewhat farther away, yet existing because of that distance. Where the H40 is more all-out 100% (in-your-face) with everything, here the EST50 takes a casual step back and creates a more real replay. Such replay takes place with strings with the H40. With the EST50 those same strings fall into a different area of the soundstage while occupying better 3D texture and reverberated nuance. Vocals are also slightly set back yet more clear with the EST50. The important part is the vocal detail in places where the EST just sounds more human. Such detail is what we pay for and are awarded. The H40 has a slight area of midrange congestion where things are just slightly clumped-together, where the EST50 takes that area apart and separates the elements for closer inspection. Now take note, often these differences would not be noted between the two IEMs, as it’s only under close inspection do these variations arise. Musically they are very close, but someone got out the Windex and cleaned the audio glass with the EST50. Meaning they occupy the same tonal arena for the most part. Yet the pace of the EST50 goes miles (off better) to show us there is more over the horizon. Such dimension exists and tells of more truth and clearer stories. The facts are there is nothing the H40 can do that the EST50 can’t. Such is the main goal in development, to bring about a more mature and refined sound. The fact that the EST50 clears off a little of the fog the H40 has, allowing us to see father into the soundstage and partake of slightly deeper timbre. The H40 has the uncanny ability to project a big sound (every instrument) but at the same time those sounds are hollow (hollow in shape, not sound) and without character in direct comparison. I’m actually doing a stand alone H40 review next, and no worries as the sound quality and value are there with the H40. It’s just you get what you pay (additional) for at times in audio. The real kicker is the fact that both IEMs fall under my description of a “golden-retriever”. Such nomenclature goes to name how an IEM acts in relation to source and file quality. Both IEMs don’t need catering to. Both IEMs gain pleasant playback from any source you have. Often at times we are trying to thread a needle by finding the tonal response that is acceptable, either by cables, tips or source choice. Here there are no such fires in existence to put out. So what we are left with is great tonal response and entertaining soundstage and all the rest of both technicalities and FR that make a winner. You just have to decide if this level of bass interaction will be distracting or not. It is distracting for me, but in the best of ways. So to sum up the H40/EST50 comparison, the EST50 comes through by doing the technicalities better therefor becoming a more detailed and real style of playback. With-in that realm of technicalities we witness the formation of actual real-life instruments and vocals. I see H40 usage with EDM outside of the house, due to it’s amazing low-end and natural noise occlusion, and the EST50 being more inside, where a more introspective and contemplative life-role takes place. The thing is, how often do you get to chose the same tonal signature in two separate IEMs? Here you could actually buy both and have the same sound signature, yet one less detailed for the outdoors, and one family heirloom to keep safe at home.

Sony XBA-Z5

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Even though the XBA-Z5 was released back in remains a force to be reckoned-with. In many ways it’s the genesis for such technological maneuvers as the H40. Probably the one cult IEM reviewed today would be the XBA-Z5. Members climb out of the woodwork all the time to defend this single enigmatic IEM release. What I’m saying is there are people who have never found anything better, and even believe it to better the TOTL Flagship IER-Z1R. Such a reputation precedes the XBA-Z5. Yet it too is not without its issues, with one major thing being fit. Have you ever placed a USB stick in your ear? No.......well I haven’t either, the shape of the XBA-Z5 does wonders to emulate the experience. Such a reach to find fit means that this “USB-stick” is falling from side to side. Though I will say if you by chance get it in place, it’s amazing. Also somehow I’m getting the same wide-bore blue tips that I have used on everything to work. The blue wide-bore are totally refining the bass, that’s normally somewhat too thick. Such a bass spectacle has really dialed the XBA-Z5 in! With the same tips and amplifier the two are close to the same in some ways and divergent in others. The bass is actually more sculpted in the XBA-Z5? Anyone who knows the Z5 may be looking at that comment with suspicion? But that’s how it sounds. I have tried the DUNU blue tips before but always thought the mids were too grainy with the XBA-Z5? The soundstage is equal between the two, with the H40 having more forward elements all across the board. Where parts of the XBA-Z5 playback seem to fall back in imaging slightly. The bass is better with the Z5, better textured and owning of a softer more elegant sound. Though upon even more investigation the H40 is actually more clear in bass and more forward. All and all the H40 has a more robust and dynamic presentation! While there is a hair more detail offered with the XBA-Z5 playback, the H40 playback is bigger and clearer and amazingly the same sound signature! It’s just with the XBA-Z5 the bass is set-off in it’s own area. Also because the bass being upfront with the H40 it’s slightly harder to visualize its individual character. Still the way it works up there in front is respectful and hardworking. But it’s interesting as the more I listen to the H40 the more vivid in comparison to the XBA-Z5 it becomes? If that vividness and contrasting sound is what you’re after, the H40 is the ticket. If you want a more set-back and old-fashion sound, go for the XBA-Z5. Due to the fit and sound character I choose the H40 as the winner, and not by a little, by a lot. When you consider you may need a 4.4mm cable with the XBA-Z5 purchase. Also the XBA-Z5 cable is a rubbery thing that creates even more havoc with fit. So an aftermarket cable is mandatory for the XBA-Z5. The H40 comes with a dynamite cable! The H40 is remarkably more efficient, and of course fits better. Not to mention offers sound occlusion benefits over the XBA-Z5. If I was to give the XBA-Z5 a single difference in sound, it would be it does offer an added level of smoothness to the sound.

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While not the most defined, it’s potent and authoritative, due to the actual-size of the bass notes. Though the EST50 does put more detail inside of the notes using the same FR, but the positioning of the bass is set back, with that added detail an imaging component forward. The H40 (bass) presence created offers a separated and large spectacle of sound, while always enjoying its place. Despite the definition (compared to more expensive IEMs) the H40 bass response has many tricks up-its-sleeve. Probably most endearing (trick) is the warm round bass “kick” that adds to moving the song forward. Such a bass "kick" also goes to showcase small accents and rhythm fluctuations, adding to foundation of groove. You see my friends, when the groove is catered to any lack of definition becomes secondary.

The way the imaging can take hold of the bass (due to it’s separation and delineation) to work wonders with movement with-in the soundstage. It’s this tautness that enables so much fun, that the bass is not only strong but firm and allocated to a zone. As at times the bass attack can offer a thrill, being you knew it in the song, but the playback was way more potent than guessed. That’s what makes a great bass, an instant realization of it’s presence, it’s like…….Oh-ya, the bass. It is in-fact this living in the moment that is musics true escape.


Critical practicality is arrived at by zero pinna gain heat ever. How many of us have a drawer-full of IEMs that dance around the phenomenon of Pinna Heat? Such a concept arrives by said IEM walking the line. The line exists of either too much or too little, but the H40 is forward (in soundstage positioning) but never goes to that line, not even near. So if you have bought Chinese IEMs and got burned by the hot pinna gain, here is your chance to throw those worries to the wind. The only way I can guess that they achieved this was by moving everything forward, but the EST50 has everything moved back and does not have pinna heat either? So I don’t know how they did it? Obviously they placed the pinna gain area FR, but my curiosity arrises to the perfect quality the vocals contain?

The H40 has a magic that while under its spell all seems correct and better than correct…….enjoyable and almost perfect. Such a place is precious and rare in the confusing world of IEM playback. It’s that everything is super forward, the furniture has been slide into the center of the room. There is not as much walking to find a place to sit, yet you are closer for conversation. And that’s how it is, people are closer talking and their points they are trying to get across come off as more vivid and almost louder. There is less breathing-room in this place, but it’s more personable and more exciting. While always confined in this closeness, epic elements still do make it out of the soundstage to emerge a noticeable musical devices. This of course happens with most renditions of midrange. While the stage is big, it’s close in proximity, but also tall. The tallness adds another dimension to complete the effect. So as noted earlier everything takes place in this big, tall and wide area. The final add is separation, the fact that all sound-features have their place. Not just a place in positioning, but a single transient place in time. Yep........the decay is roughly technical, which brings clarity.

Some would actually argue for more. It’s defiantly your call if more upper-treble needs to be included? You can visualize but the upper end sparklers are not brought out for us to play with. We can still hear their existence and their reality known, yet not always experienced to the full-extent. Such cymbal accents are never viewed eye-to-eye. They are further away and their fall-off reverberations even further. Do I give a Schiit? No, I truly don’t care. Remember I’m in paradise here. The amount of included musical information is separated like only a Hybrid could do. So with the included lack of pronunciation, we at least get separation with goes the full-gambit to add what musical information is needed. Any lack of physicality missing in the upper-treble is fully reinforced by the mid-treble and lower-treble. This is why the ISN H40 promotes the illusion of completeness and balance. Such energies are needed also to counteract the bass energy. Where the bass and midrange go overboard for the price, maybe the treble is the place you get exactly what you pay for? Still just like often found in life, the H40 gets heard as the complete package therefor bigger/more vivid/more bold and more real than the price of admission.

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Skiing in on new Hybrid Technology, ISN not only shows us what’s possible, but goes way overboard in robust and involving sound reproduction. Such qualities may be a sign-of-the-times, yet the ISN H40 is found to be different and special due to tuning. It all becomes an epic accomplishment of epic proportions, and that's not just describing the soundstage. Such big bass joined with all the rest of the (forward placed) sound doesn’t mess around. While not providing everything, I challenge anyone to try the ISN H40 and not tell me it’s complete and competent. Be it your first step into the world of audiophile IEMs, or the additive to a collection, the results are the same; a unique and valuable single example of the art. Easily a deserted island IEM, due to playing your whole library and mixing with all your gear.

Such sonic findings were a surprise for me, when I made eye contact with "The Tiger". The build being different than other seemingly similar builds, the way the nozzle is polished and fastened. The fit and the daily use. The included (cable-manufacturer’s) S8 cable results in very little if any sound-quality left on the table. The sound of the H40 is truly the sound of an IEM motor firing on-all-cylinders. While it didn’t come out this week, that does not make the H40 lacking any modern advancement. In-fact the introduction of the H40 was the first example of this new wave of value and ability to come along and thrill the market. The profound uniqueness combined with usability make the H40 special in my experience. The H40 is the very definition of a bang-for-the-buck purchase. A stone-cold classic waiting for another listener to find enchantment. If your finding yourself veering away from the old-style audiophile sound and guess that you may like enhancement on all fronts……..if you guessed while reading that this sound described is for you, you truly can’t do any better.

You can purchase the ISN H40 here:

Disclaimer: I would like to thank Penon Audio for the opportunity to review this IEM.
Disclaimer: These thoughts and ideas are of one individual, your results may vary.

Equipment Used:
Sony WM1Z Walkman DAP MrWalkman Firmware 4.4mm/3.5mm
Sony WM1A Walkman DAP MrWalkman Firmware 4.4mm/3.5mm
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
Apple iPad

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alexandros a
alexandros a
The holly grail of monitors....
Timeless value.......
Congrats, you covered a lot of ground with this insightful and thorough review!
Thank-you. Yes, somehow there was a bunch of stuff to talk about? I don’t know how there was so much?


Headphoneus Supremus
Analogue Grandeur
Pros: Excellent bass response
Wide and tall soundstage
Analogue romanticism and musicality
Non-fatiguing tuning
Quality cable included
Competes above price point
Cons: Would prefer more upper treble extension
Unboxing underwhelming
Driver configuration:

1DD + 3BA
1 dynamic driver (9.2mm) – low frequency
1 BA (custom) – middle frequency
2 BA (composite) – high frequency
22ohm impedance, 105dB sensitivity, 20Hz-20kHz
MMCX connectors, ISN S8 silver-plated OCC cable included (3.5/2.5/4.4mm terminations available)

Source: Shanling M8 (4.4mm, turbo gain)
Burn in: 150hrs
Stock cable, stock silicone tips (green bore)
Genres tested: world music, jazz, ambient, electronic, classical

The ISN H40 was provided by Penon for the purposes of review and in exchange for my honest opinion. Penon have no had sight or say on content within this review. This review contains earlier impressions I’ve posted publicly and my opinion is largely unchanged from then. The ISN H40 can be purchased here.



Funnily enough, I entered the hobby at around the same time the ISN H40 came onto the market. At the time I had little knowledge of my own preferences and ended up with the Mangird Tea and the Shuoer EJ07, both had their strengths but I ended up moving on quite quickly and further down the tribrid rabbit hole. Most recently, I’ve returned to single dynamic drivers (in the form of earbuds and IEMs) and armed with the knowledge of my preference curve (somewhere between L-shaped and W-shaped) I discovered the Penon house tuning that I’ve grown to love in multiple forms.

Aware of the close working relationship of ISN and Penon, I was encouraged to try the ISN H40. Prior to receiving the H40 a part of me hoped there would be more than just a little Penon inspiration in there (in the way of mid-centric warmth), to keep me interested. There was also plenty of feedback on the forums complimenting the H40’s soundstage and bass response that piqued my interest…

Accessories & Packaging

To be straight to the point here – the packaging was underwhelming. A very thin cardboard box with outer and inner sleeves in a vibrant foil blue. Thankfully the IEMs are cushioned well within the sleeve using foam inserts. There is a functional and sturdy leatherette ISN carry case included that some might find useful. In terms of eartips there is a good selection of silicone tips and foam tips. All have a reasonably large inner diameter to encourage more treble energy through. A useful cleaning brush and cable clip is also included.

The cable – the ISN S8 – is beautifully made. It’s lightweight and has a very clear plastic sheath that reveals the silver plated OCC inside. The cable accessories are solid and well-built and the chin slider functions smoothly as intended. As a cable believer the choice of silver-plated OCC pairs well with the darker than neutral tuning to clean up and enhance the treble definition while retaining the low end extension and detail offered by OCC.




Design, Build, Fit and Comfort

The design of the shell is ergonomic and has a form-fitting shape to it. However, it’s also quite tall to the shoulder so it doesn’t sit flat to my ears and occupies all of the concha (plus more) within my smaller than average ears. It’s not uncomfortable and by virtue of the shell size and the solid resin shell the passive isolation is above average. The nozzle width at its tip is 4mm in diameter and fits nicely within the ear canal. As mentioned the shell is solid resin in a dark blue to black colour with gold ISN labelling. There is a single vent to the rear of the shell. The H40 looks sleek and is reasonably understated in its appearance. Overall, I’m very satisfied with the build but would prefer a shorter shell to the shoulder and a slightly narrower neck (before it meets the metal nozzle) to allow for a deeper fit.





The tonality here is a L-shape to V-shape with upper treble roll off. It’s got a distinctly analogue feel to it. It’s ‘musical’ rather than analytical and makes for emotive listening.

Bass: strong impact, subbass emphasis, deep extension, texture and timbre retained

The bass is the standout feature of this IEM, with some of the best subbass rumble I’ve heard. It has a fine balance of subbass to midbass with emphasis leaning to the subbass. The H40 offers up great quantity in the lower frequencies without losing detail or nuance. Subbass rumbles with authority and fills the stage very well while the midbass impact is satisfying. As the midbass isn’t over emphasised, detail in the lower frequencies are on full display and timbre of instruments is conveyed really well. Listening to stand-up bass and double bass strings is a pleasure. The DD doesn’t display the hardest impact or the quickest transients but its character is perfectly suited to the analogue-inspired sound ISN were clearly aiming for.

The rest of the tuning revolves around this strong low frequency performance.

Midrange: no shout, warm, reasonable resolution, slight recession

The midrange is interesting and not uninspired. It’s definitely not forward – something that became more apparent as I’ve spent more time with it. The large stage (another selling point to be mentioned later) emphasises a slight recession in the mids as does the restrained pinna gain. They don’t feel empty or disembodied but neither do they feel the overwhelming focus of this IEM in busy tracks. I would have preferred some greater upper mid/lower treble presence to add some bite. Tonally the mids are warm and rich and not lacking in detail or clarity. Lower midrange vocals and instruments have some great weight to them that when combined with the bass boost and soundstage gives the impression of listening to larger over-ears.

I personally have a preference for a more forward midrange with greater upper mid presence but on reflection, combining the controlled pinna gain and less aggressive uppermids with the large soundstage and bass enhances the sense of space and analogue warmth. There is an old-school ‘speaker-like’ presentation wherein the bass encompasses and supports with a very engaging atmosphere around the midrange. Thankfully, the midrange never feels cluttered by this bassy embrace and details aren’t obscured in the process.

Treble: good definition, smooth presentation, no sibilance, upper treble roll off, minimal air, some metallic undertones

The treble stays on theme in the H40. It’s smooth and controlled but not subdued. You have definition, but it’s not piercing or shrill. The tuning ensures the overall tonality remains organic, more musical and less analytical. It also allows the listener to increase the volume to bask in the joy of the low end without fear of sibilance. If I could ‘nit-pick’ I would prefer greater ultrahigh extension to balance the tuning slightly and emphasise the space even more.


Soundstage – The second selling point of this IEM just behind the bass is the soundstage. It’s large in height and width and is closest to ‘concert hall’ I’ve heard at this price range (take this with a pinch of salt as the intangibles like soundstage are very subjective). The width means the bass doesn’t become fatiguing or feel invasive and the height brings a sense of scale to the musical performance that makes it feel grand (especially classical music). It also counteracts the lack of treble air by emphasising space.

Imaging, Instrument Separation & Layering – Imaging is great for the price and the H40 gives a great rendition of many of the Yosi Horikawas tracks. There is great depth that makes layering and three dimensionality stand out.

Timbre – As a self-proclaimed timbre-head I’ve not had issue with the BA implementation here. The tuning ensures things stay warm enough and the defining bass character of the DD keeps things organic. There is the rare occasion when there is metallic timbre in the lower treble but it never put me off reaching for this IEM. I have no issue with the timbre presentation in the bass or mids. Fundamental and harmonic detail feels intact and is sustained well with no BA ‘sputtering’.


From the very first listen out of the box the H40 has flaunted a character that I’ve found quite unique and appealing. For the price (and more) it achieves a level of versatility, character and technicality that is hard to find. It quite easily sits as my choice of hybrid below $200, representing excellent value for money. ISN has created a bold and fun IEM that never becomes abrasive. It presents music with an ‘analogue grandeur’ that is as addictive as it is inviting.

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alexandros a
alexandros a
Analogue & grandeur presentation are the key words here...
The overall ambiance that H40 is able of creating of, due to it's bombastic and spacious presentation surely can makeup for the lack of air in the upper treble
  • Like
Reactions: ian91
Thanks for the review! H40 or Penon Globe is better?
One of the best, easy to Access review I see over here.

Totally agree with ur conclusion, a fun an analogue way to create a unique iem.

The only counterpart is the MMCX conector.



New Head-Fier
Hey all! Love the reviews for this IEM so far. I was dead set on getting the Ikko oh10's but suddenly the H40's jumped out from the shadow realm, and im wondering if anyone can do a comparison between the two. Looking for a deep but detailed and resolve bass that knows when to shine, mids that aren't recessed too much, holographic soundstage, and sparkling highs. Lemme know what you come up with!


Wow, reading all these reviews made me purchase a pair from Penon Audio. What service! Only took two weeks and just been notified delivery today. I cannot wait. Using Shure SE215 + SE. right now. Decent but SMALL AND NARROW SOUNDSTAGE. I wanted more bass too, as SE15 can sound somewhat thin on some recordings. I only use DSD and high resolution FLAC on my newly purchased A&K SR25 Mark II. Astonishing DAP too. Im not the eloquent commentator you all are, but impressions after a few days use coming.