Pros:

• Exceptional MEMS treble implementation that extracts fine micro-details without any spicy fatigue.
• Very snug and comfortable resin shell design that fits better than the Moondrop Dusk.
• Massive, orchestral soundstage width with excellent stereo imaging.
• Included ear tips provide a sticky, highly secure acoustic seal.
• Utterly clean and uncolored midrange that lets vocals shine naturally.

Cons:

• Lacks authoritative sub-bass rumble and mid-bass slam (not for bassheads).
• The stock braided cable is stiff, retains wire memory, and feels a bit unwieldy.
• The compact black puck case is too small to carry large dongle DACs alongside the IEMs.

Welcome back, audiophiles! It’s me, your boy Joe, back again with another review! Today we are looking at a highly anticipated collaboration: the Moondrop x Crinacle Silicon. Retailing for $249.99, this set packs a 1DD + 2BA + 2MEMS tribrid architecture. Let's see if this MEMS implementation lives up to the hype!

Video Review:​

https://youtu.be/9ihsSeolKcI

Disclaimer​

A huge shout-out and thanks to Shenzhen Audio for providing this unit for review! As always, all thoughts, sound impressions, and basshead cravings are 100% my own with zero biases whatsoever.

Pricing & Specifications​

• Price: $249.99 USD
• Driver Configuration: 1x 10mm Dynamic Driver + 2x Balanced Armatures + 2x MEMS Drivers
• Cable: Modular black and blue braided cable with screw-locking 3.5mm and 4.4mm terminations

Gear Used for Review & Drivability​

I tested the Silicon on my Shanling M3 Plus and the KD-01 Pro from K-Design. While you can run it off a laptop, doing so robs you of bass dynamics. It drives well, but give it a proper source to get the most out of the low end!

Design, Build, Fit & Accessories​

• The "Mega Chongster" Unboxing: The box for this is absolutely massive and features Moondrop's signature waifu art. However, once you get past the huge packaging, the actual IEMs and the black puck case are quite compact.
• Shells & Fit: The metal faceplates feature ventilation grills, and the beautiful resin finish is very reminiscent of the Blessing 2 and Blessing 3. The physical fit is snug, ergonomic, and much better for my ears than the Moondrop Dusk. I can wear these for long hours with zero fatigue.
• Cable & Tips: The included braided cable is unfortunately a bit thick and stiff with some wire memory, though its metal chin slider works perfectly. For ear tips, Moondrop includes standard hybrid foams (which got too heated for my ears) and "Latex" ear tips. The Latex tips are sticky, provide a great seal, and are what I recommend if you stick with the stock options.

Sound Impressions​

The Moondrop Silicon is a highly detailed, neutral-leaning all-rounder.
Bass: As a basshead, this is where it falls a bit short for me. It lacks aggressive mid-bass slam and the sub-bass rumble feels lackluster. It is a very tastefully done, nuanced bass response that neutral heads will love, but it won't satisfy those seeking heavy thump.
Mids: The midrange is utterly clean and super flat with absolutely no coloration.
Treble: This is where the MEMS drivers shine! The top end retrieves excellent micro-details, especially in vocal nuances, without ever becoming spicy, peaky, or fatiguing.

Song Impressions​

• "Are We There Yet" by 32Stitches & BAER: The first thing I noticed is the massive, orchestral soundstage width. The female vocals pop out exceptionally crisp and clean. While the bass drop lacks the slam I crave, the MEMS treble handles the high frequencies beautifully. If you crank the volume too high trying to find the bass, the treble can creep in, but at normal levels, it is very detailed.
• "Tactic" by Daoko: This track proves the Silicon's staging capabilities—the music feels like it's coming from a distance, placing you in a wide acoustic space. The bass details and heartbeats in the track are rendered well, even if the raw thump is missing. Daoko's female vocals remain clean and completely fatigue-free.

Overall Impressions and Verdict​

Rating: 3.5 / 5 (For Bassheads) | 4 / 5 (For Neutral Heads)
The Moondrop Silicon is a fantastic step up from the Blessing series if you want supreme MEMS micro-details and a neutral, uncolored sound. The fit is excellent and the treble is fatigue-free. However, as a self-proclaimed basshead, the lack of sub-bass rumble and slam means it only scores a 3.5 out of 5 from my perspective.

TL;DR

The Seraphim is a great V shape option that retails at $259 for anyone looking for a bombastic, exciting and contrasty sound signature with plenty of “technical performance” and surprising treble refinement while sacrificing mid range body and naturalness. It’s also extremely pretty.

Context

This iem was kindly sent to me by Jay and Linsoul for review, all thoughts and opinions are my own. I usually prefer iems that are non sibilant with relaxed upper treble and upper mids and raised lower mids that add body to the sound (kinda the opposite of harman ie 2019) but I can appreciate a variety of sound signatures if they’re done well.

Design, Build, & Comfort

• Aesthetics & Build: The iems are made of aluminium, build quality feels great. The shells are super light weight despite being metal. There is a big rear vent and a wavy etched pattern on the faceplate which looks incredible irl, plays well with the light. This is definitely the best looking ziigaat iem yet. The nozzles are metal as well with a metal grill to prevent dust from entering the iem, ziigaat includes 2 pairs of spare mesh filters which is nice to see. The cable matches the shells really nicely as well.
• Fit, Comfort and Isolation: These iems are definitely on the larger side, with some semi custom contouring so it fits me well. The nozzles are super short so people with smaller ears should also be able to wear it since you’ll be relying on larger than usual eartips for a seal anyway. It’s a shallow fitting iem. Isolation is just average, not particularly open sounding like the large vents would indicate (which is a good thing for me).
• Cable & Accessories: The cable is genuinely great, it’s a thin and lightweight single wire stand that splits at the y split, matches the shells beautifully. Has a functional chin slider. It’s definitely one of the better cables I've handheld in the price range, it doesn’t feel thick and heavy for the sake of being premium, doesn’t have a ton of memory or feel stiff. The swappable termination is unnecessarily long tho, and it doesn’t have a screw to hold it, it’s just friction fit. So you have to hold it near the ziigaat logo to make sure the termination doesn’t come off. It comes with a big leather ziigaat hardshell case, 3.5 mm and 4.4 mm terminations, spare nozzle mesh and 3 sets of eartips, foam and translucent sticky eartips in grey and white, no complaints with the accessories.

The Sound

The Seraphim has a 2 DD + 3 BA driver config, tuned by Jay Audio to a V shape sound signature with inspiration from Subtonic Storm and Ziigaat Odyssey.

• Bass (20 hz to 300 hz): The Seraphim has a ton of bass, almost a bit too much for my tastes but it is extremely well defined and quality bass. The bass shape pushes the sub bass more forward than the mid bass which isn’t my favourite style of bass (reminds me of harman ie 2019) but seraphim avoids the boomy and thin bass style of harman by adding way more mid bass (200 hz). As a result mid bass instruments like kick drums feel fast and tactile with adequate fullness, bass guitars sound super well defined with some of their gritty and abrasive characteristics overemphasized (due to the treble we’ll talk about later). Subbass is very well textured again, synth drops and low organ notes sound great, and the linear bass rise prevents a detached sub woofer style bass a lot of basshead iems like deuce have. Bass is probably the best part of the seraphim for me.
• Mids (300 hz to 6000 hz): There is a very audible lower mid range dip (300 hz to 1 khz) which gives mid range instruments a hollow and thin presentation (very harman like here). I find this especially confusing since both the storm and odyssey (the iems which seraphim takes inspiration from) have the characteristic filled in lower mids of new meta sets but none of that is present on the seraphim. While this does give a good sense of spaciousness and excellent instrument separation, male vocals, guitars, pianos and most mid range instruments sound thin and lacking in body. Female vocals fare a bit better, they're exciting and lively and have none of the nasal and shouty characteristics of harman (gentle pinna rise and relatively relaxed 3k). The scooped mid bass to mid range transition does give the seraphim a detached bass presentation which I don't particularly like. Overall the midrange of the seraphim is super energetic and exciting but it’s far from natural, very coloured, contrasty and imo, the weakest part of this iem.
• Mid & Upper Treble (6000 Hz to 20000 Hz): Treble is another strong suit of the seraphim imo, yes it is very boosted (particularly in the mid treble) but it is not peaky or harsh. The treble is surprisingly refined for what is a bombastic and exciting sound signature, there are no audible peaks or dips even via sine sweeps and as a result both the fundamentals and upper overtones of treble instruments are equally emphasized which I find a lot of iems struggle to do, usually emphasizing one over the other due to peaks or dips in my ear. The lower/mid treble boost gives kick drums, bass guitars and acoustic guitars that extra bit of edge and definition. There is also a considerable upper treble boost for ✨Resolution✨ which my warmpoo ears usually don’t like but the aforementioned lack of peaks makes it very tolerable. There is no added sibilance or zingy-ness to the tonality which a lot of iems with sore peaks (like heyday and davinci) have. I find this particularly shocking since jays audio and I usually have polar opposite treble preferences but the seraphim has one of the smoothest treble presentations I’ve heard.
• Subjective Technical Performance: The Seraphim has excellent imaging performance, instrument separation and upper treble detail retrieval, along with the contrast that comes with a V shaped tuning. I think anyone chasing “technicalities” in iems would be more than satisfied with the seraphim.

Comparisons

Compared to some other popular iems:

• Dunu Davinci: Seraphim bass sounds more dynamic but the davinci has a way more natural and fuller sounding midrange. Upper treble peak ruins davinci treble for me while the seraphim is smoothened out. Seraphim is more comfortable with a better cable imo..
• Letshuoer Cadenza 4: Seraphim has significantly more bass and smoother treble, Cadenza 4 has a slightly more filled in and comparatively more natural midrange, but both are more scooped than I would like.
• Tangzu Heyday: Seraphim has better bass, better upper mids and is way less fatiguing and less zingy in the treble, is also significantly lighter despite both being metal, im just not a big fan of the heyday.
• Kiwi Ears Aether: Significantly less bassy and more filled in lower mids than seraphim but the aether treble is super punishing for me, and the lower bass shelf fails to balance it out only making it worse.
• Aful Explorer: Very different iems, explorer is much more full bodied than the seraphim with better male vocals but worse female vocals, bass on seraphim is a little better and overall the seraphim is much more livelier and higher res sounding due to upper treble boost. Explorer is more comfortable with better isolation.
• Truthear Pure: Wayy more natural than the Seraphim, much better mid range overall but it’s not nearly as exciting, contrasty or bombastic as the seraphim, I dont get the 7k peak on the seraphim like I do with the pure.

Who Should Buy This? 

• People who want an exciting and lively sound signature.
• People who enjoy contrasty sound signatures with boosted bass and treble
• People like harman but want more mid bass
• People who prioritize technical performance

Who Should Avoid This?

• People that want a natural or neutral iem
• People that want a warm or relaxing sound signature
• People that are treble sensitive

Price: $59.99 | Score: 7.5/10

The DUNU Subsurge, launching October 20, is a $60 dual-dynamic IEM with a 10mm LCP bass driver and an 8mm titanium-coated driver for mids and highs.

I generally prefer warmer tunings, while DUNU tends to sound a little cooler and brighter to my ears. Subsurge follows that character, but the bass makes it a genuinely fun listen.

As always, I maintain a running ranking list of 170+ headphones, IEMs and other audio products, with ratings and short impressions. The link is in my profile if you are interested.

Bass

This is easily my favorite part of Subsurge. Guess that's where the name comes from... sub bass surging... 👀.

With the right tips, particularly DUNU Candy and SpinFit W1, that bass driver really knows how to wake up a song.

I spent quite a bit of time listening to my full library and loved the bass on:

• Purple Sun and I Get Weak by Cannons
• bad guy by Billie Eilish
• The Weekend by 88rising & BIBI
• Nishanka and Lost in the labryinth by Contra & Pushloop

The bass hits hard, has good sub-bass presence and makes these tracks come alive. What I particularly enjoy is how it responds to the music. When the track demands bass, Subsurge delivers. When it doesn't, the low end stays under control. It is lively without becoming muddy or bloated. For the people who complain about "muddy bass" on the red lions, this is the antidote imo.

Mids / Vocals

Vocals stay front and center without becoming shouty. That is already a big win for me given my sensitivity around 3kHz. Most of my music sounded great, but there are some limitations in resolution.

(Everything I Do) I Do It for You by Bryan Adams is one example where vocals can lose a little definition. On busier tracks such as It's My Life by Bon Jovi, separation also starts to struggle. These are not constant issues. I would say nine out of ten tracks worked perfectly well for me. Generally I find vocals boosted compared to similar budget sets.

Treble / Air

Treble is generally very safe, with good clarity and no obvious peaks that triggered my usual sensitivities (around 6-7K Hz). I would have liked a little more extension and air in the upper treble. The presentation can feel slightly constrained up top compared with some of my other IEMs.

The benefit is that vocals stand out more than on something like Red Lion or NICEHCK Tears, without the upper frequencies constantly demanding attention.

Gaming

I also spent time gaming with Subsurge and came away reasonably impressed. Imaging is precise, and I had no particular difficulty following positional cues.

The limitation is soundstage. It feels relatively small compared with some of my favorite gaming IEMs, so there is less sense of distance and space. For games like BO7 MP it is absolutely fine. Also single player games like Gears of War E-Day with small corridor type level design there is no disadvantage. In larger arena shooters, some limitations start to show up like trying to guess distance to target in BF6. Still, I could game on it just fine.

Build / Comfort / Accessories

First, these shells are beautiful.

The deep-blue, galactic starfield finish is easily one of my favorite things about Subsurge. The resin shells also look and feel more expensive than the asking price suggests.

The shape reminds me quite a bit of 64 Audio IEM shells, which have consistently been among my favorites for comfort and fit. I really like this style of ergonomic shell, and DUNU has done a great job with the design. At approximately 6g per side, they are also lightweight.

The package is generous:

• Ten pairs of ear tips, including DUNU Candy and S&S options (that's 25$ value right there)
• A thin, attractive and compliant copper cable and I really like the turquoise / blue-ish color
• A functional storage pouch
• A cleaning kit

My only real complaint is the 3.5mm-only termination on this version. I would have preferred interchangeable 3.5mm/4.4mm connectors, like the system included with Juzear Nimbus.

DUNU also has a separate USB-C version with a microphone.

Comparisons

Tangzu Red Lion

Subsurge gives vocals more prominence, while Red Lion, particularly with Penon Liqueur Orange tips, has more upper-end air and a larger-feeling presentation.

NICEHCK Tears

Subsurge is cooler and more energetic. Tears has a warmer, more relaxed sound with excellent bass rumble. Its tiny shell is also exceptionally comfortable.

Juzear Nimbus

Subsurge has a more straightforward tuning. Nimbus offers multiple nozzles and greater tuning flexibility, although I strongly preferred the white nozzle. I also found Nimbus struggled to maintain separation during chaotic gaming.

Juzear Defiant

Subsurge is the cheaper option for bass-focused listening. Defiant is technically stronger, with better staging, layering and separation. It remains my preference for a music/gaming all-rounder.

Final Thoughts

Would I recommend Subsurge at $60? Yes, particularly for pop and bass-focused music. I think it is the best I have heard at this price or below it thus far. It is quite the banger. If you want impactful bass, prominent vocals, comfortable shells and a generous accessory package, this is a very good purchase.

If your priorities are bigger stage or competitive gaming, I would spend more on something like Juzear Defiant.

I would also happily take Subsurge over quite a few IEMs I have tried in higher price brackets. The $50–100 category is brutally competitive, but Subsurge has enough going for it to earn a recommendation from me. Having said that my experience in this price bracket remains limited. Though, from the ones I have tried like Chu 2, Red Lion, Tears, Gate, HE Cai Wen Ji etc., I feel the extra spend might be worth it for some.

And those gorgeous blue shells certainly don't hurt.

Finally, thanks to HiFiGo for sending Subsurge over for review. They had no input into this review, and all opinions are entirely my own.

Hello guys this is my review of the Twistura Delta.

Note that I bought this iem with my own money not provided by brand or anyone.

Twistura delta have 10mm LCP dynamic driver comes with 3.5mm and type c termination.

Unboxing

The Twistura Delta comes with the iem and many pairs of silicone eartips, including 1 pair of liquid silicone eartips which kinda look similar to the TRN T1 eartips. It also comes with a carrying pouch made of soft fabric. I bought the type c version, but there is no dsp chip inside the cable , The cable attaches via standard 2 pin connectors. The box is also quite small.

Look, Feel, and Fit

From the looks and feel, the iem shell looks very good. It is a bit heavy coz of the full metal body, so it doesnt look or feel like a 30 usd set, but rather something more premium. However, the shiny surface does attract fingerprints and dirt on the shell. The shell itself is not too big, but as I said, it feels a bit heavy.

On the other hand, the cable looks and feels very cheap, but I dont have a problem with that since I actually prefer thin and light cables.

For me, this is one of the most comfortable iems I have used in the 30 usd category. My main concern with iems is nozzle thickness. Most iems with thick nozzles are not comfortable for my small ears, but I noticed that iems without an upper lip on the nozzle are much more comfortable for me. The same rule applies here with the Twistura Delta. Instead of an outer lip, the Delta has 2 small bumps on the side which provide grip for the eartips while giving a better fit and comfort.

Though for some reason, the right side of the shell sometimes slips out of my ear. Idk why, but I never had this kinda issue with other iems where one side is slipping while the other side stays fine.

Sound Profile

It's a neutral warm iem but i would say sometimes it kinda sounds bit bright .

Now here is where I am most impressed. If you have checked my past reviews, most budget iems sound so similar to me, mostly v shaped sets that struggle in the mids. The Delta sounds a bit fresh. It is kinda u shaped with a slight mid boost. Where most budget iems around 30 usd struggle with messy mids in busy tracks, the Delta somehow manages to provide much better separation.

Soundstage -

The soundstage is wide but only for the price don't expect too much .

Technicals -

Detail retrieval is just enough and decent but the separation is top notch at least in the mids .

Sibilance -

You won't find sibilance or spicy treble or Shouty vocals unless you are pushing the volume too much ..

Lows and Bass

The sub bass provides good depth and the mid bass has a nice kick to it. It gives you a feeling of openness and doesnt sound dark at all. Its not too bass heavy, but the texture is very solid unlike most single DD have rumbling slow kind of bass this one is more like fast puchy bass .

Mids and Vocals

This is my favorite thing about this iem. After trying so many budget iems, I would say this is one of the best I have tested for midrange separation, even in busy tracks with heavy electronic sounds. The vocals are neither too forward nor too recessed. Both male and female vocals sound balanced. Male vocals have the right amount of thickness without sounding thin, and female vocals dont sound overly forward or shouty.

Highs and Treble

This is probably the weakest point for me, not because its bad, but because I was impressed so much by the mids. The Delta does have a bit of sibilance, but it only occurs when the volume is on the higher side and in specific tracks. Most of the time it doesnt feel fatiguing at all. It is airy and provides enough sparkle, though it misses some micro details. But that is completely understandable for this price.

Overall, I would say this is the most value for money iem in this budget and it sounds refreshingly different.

Who Should Buy

Anyone looking for a different kind of tuning in a budget set, max value for money, or a balanced u shaped iem with clean mids and a comfortable fit.

Who Should Not Buy

It is hard to find major flaws for this price range, but skip this if you are a hard headed basshead, want super sparkly treble, or expect high end technicalities (which is kinda impossible in this price range anyway).

Verdict

The Delta is easily my top pick right now in the sub 50 usd category, but thats my preference coz it gave me one of the best fits I have ever got under 50 bucks. It has solid bass quality, awesome mids, and treble that is good enough. The accessories are decent too!

​

Disclaimer - I was loaned this iem as a part of a review tour by Sushiifi and DUNU. However, I'm NOT affiliated with dunu and hence it will not impinge on freedom to criticize the iem. All my opinions are my own.

INTRODUCTION

• The DUNU SA6 mk2 was launched in April 2023 at $579.99

· The SA6 stands for studio armature 6 , signifying the driver configuration.

• The DUNU SA6 MK2 utilizes a 3-way crossover specialised network design housing 6 balanced armatures - 2 Sonion balanced armatures for bass , and 4 Knowles balanced armatures for mid range and treble.

BUILD AND COMFORT

• The semi custom shells are lightweight but the shells are chonkers when it comes to the width. They will stick out from your ear quite a bit. It has an "Immersion switch" a.k.a bass boost switch on each shell that you can toggle with your fingers without the need of a tool. The switches are placed in an ergonomic spot so that you can switch them on/off on the go without removing the iem from your ear.

• The acrylic resin shell is "Hand poured" and capped by a "High grade stabilized wood faceplate" . Dunu claimed that the wood grain pattern is different for each shell making your specific iem "unique to you". I personally don't like this colour.

• The SA6 is comfortable to wear but there's a catch , slight pressure build up was an issue to me. It seems that the iem drivers are vented to the inside space of the shell and not connecting to an outlet on the shell.

ACCESSORIES

• The cable is the hulk pro mini which is a single crystal copper core wire featuring "Q lock plus" swappable 3.5mm, and 4.4mm right-angle termination jacks.

• Dunu generously provides 11 pairs of eartips which includes 3 pairs of dunu candy tips, 4 pairs of Dunu S&S tips and 3 pairs of standard balanced silicone tips and 1 pair of memory foam tips.

• A puck shaped leather carrying case, a cleaning brush for removing ear wax , a user manual, and paperwork are included in the box.

SONIC PERFORMANCE

Note : all the notes are with the bass boost switch on. When compared to the off mode ( 6 db shelf) , the boost is a modest 1 - 2 db (8 db shelf)

SOUNDSTAGE, DETAILS, AND LAYERING

• The soundstage is moderate to actually wide with real depth. Some instruments/sounds are placed further away than others. They feel like they're about half a foot away from your pinna. This width is not consistent and depends on that particular song.

• Detail retrieval is good in general but it's similar or average when compared to peers in the $500 range. The top pro is superior in this regard especially when it comes to micro details.

• Instrument separation and layering is good but not spectacular. You can pick up where an instrument is playing and separate that sound from the song.

BASS

• The SA6 mk2 has tasty amounts of sub-bass rumble with bass boost on. The dunu candy tips further accentuates this . The sub bass does not muddy the other frequencies but lends to an overall warm sound signature.

• The mid-bass is punchy with good amount of slam. Bass texture is perceptible while the attack and decay are the right duration without bloom or bloat.

• The bass is rather good but don't expect it to sound like a Dynamic driver. It's still the characteristic BA bass.

MIDS

• The mids are tinted warm , this is an unapologetically warm iem. This iem is studio in name only , not in practice.

• String instruments are clean but with a smooth edge.

• Woodwind and brass instruments sound well bodied and rich.

• Male vocals have that extra oomph provided by the warmth. Not accurate but fun.

• Female vocals in the lower register sound comforting and lush.

• I have to say that sometimes the vocals feel too far away or distant. It loses that intimacy that some songs require. This doesn't not occur in most songs but it does occur now and then.

TREBLE

• Cymbals sound smooth without sibilance. There's one issue as a result of the wide soundstage, sometimes cymbals are pushed far away due to which they may sound washed out or muffled or low res.

• Female vocals with a higher frequency pitch are handled reasonably well. There is no vocal sibilance to speak of. Even in the upper register, they sound breathy and lush. The trailing resonance notes are perceptible.

• Snare drums and string instruments have that initial crisp note .

• The mk2 has good treble extension and presence in the air region. Details are not forced on you but are easy to find if you look for them. It's like a high resolution picture taken on your phone , you have to zoom in to find the details.

• The transient response is clean and tight. There is no reverb or artifacts. The BAs are fast and resolving.

CONCLUSION

• The SA6 mk2 is 3 years old now and I think Dunu went a little too safe with the tuning on these. Yes they sound warm and comforting but does it have the staying power in 2026 ? The last 3 years feel like a decade of progress. The Dunu 242 has better mids and equally if not more detailed bass at $350. Is the Dunu SA6 mk2 worth the $500 in big 2026 ? I'm not convinced but I won't take away the fact that this iem is competent. Good sound stays good and that's all that matters.

EARTIPS USED: Dunu S&S , Dunu Candy and Sancai balanced.

Tracks used -

- Killshot by Eminem

- GDFR by flo rida

- Another one bites the dust by queen

- Toxic by britney spears

- Winter , four seasons by vivaldi

- Mexico by vitamin string quartet

- When I'm down by Chris Cornell

- Show me how to live by Audioslave

- Angel of the morning by Juice newton

- Monomyth by Animals as leaders

- Fuel by Metallica

- Novocaine by Amber rubarth

I got interested in this because I keep seeing the claim that you can’t EQ a cheaper IEM to sound like an expensive multi-driver IEM because crossovers make them non-minimum-phase.

Thankfully, this is all measurable, so we don't have to rely on guesswork or anecdotes.

So I calculated excess group delay from HypetheSonics impulse-response measurements for a few IEMs.

The result surprised me: most of the deviations are tiny. Even the larger ones are still well below the lowest mean audibility thresholds reported by Liski et al. (2021): about −0.56 ms / +0.64 ms under very revealing test conditions.

The reason minimum-phase behaviour matters is that, for a linear minimum-phase system, the magnitude response also determines the phase and transient response. So things like “driver speed” or “transient quality” are not separate hidden variables once the FR is matched.

That doesn’t mean FR contains literally everything. Distortion, channel matching and fit can still differ.

And even if someone could hear a 0.1–0.2 ms excess-delay difference, why assume it is a good thing?

If I EQ a Salnotes Zero to match the magnitude response of a more expensive IEM, and the Zero remains closer to minimum phase, then the remaining phase difference only proves that they are different — not that the extra delay is responsible for better “technicalities”.

So I’m increasingly skeptical of the argument that multi-driver phase behaviour is a major reason why EQ can’t reproduce the sound of another IEM.

Sources:

HypetheSonics Jdata database

Liski, Mäkivirta & Välimäki (2021), Audibility of Group-Delay Equalization, IEEE/ACM TASLP. DOI: 10.1109/TASLP.2021.3087969

I bought the Softears RSV MK2 with my own money. Nothing sponsored or affiliated.

I also maintain a running ranking list with 170+ headphones, IEMs and other audio products in the link in my profile.

Score: 8/10

RSV MK2 was my best of show at CanJam 2026. I loved the bass, detail, smooth presentation and, most importantly, thought I had finally found an expensive IEM that did not trigger my treble sensitivities.

Ownership changed that.

Three tracks exposed the problem the most:

• 12 to 12 - Sombr
• Chasing Cars - Snow Patrol
• Jaded - Koe Wetzel & Ella

There is a metallic zing on certain vocals that I eventually traced to problem areas around 3.3kHz and 7.2kHz for my ears.

Bass

This is still my favorite part of RSV MK2. There is a lot of bass, but it stays controlled, textured and clean. Compared with something like Martilo, RSV MK2 carries more mid-bass instead of concentrating most of its energy down in the sub-bass. That gives drums and bass lines more body without turning muddy. It can hit hard without taking over the presentation. Some of the notes were really like a kick in the guts. I loved it!

Strangely, some tracks can still sound a little lean overall despite the amount of bass. I think that comes more from the rest of the tuning than the low end itself.

Mids / Treble

Most of the time, RSV MK2 sounds smooth and refined.

Then you hit the wrong vocal. Chasing Cars gives Gary Lightbody's voice a sharp edge. I heard similar problems on 12 to 12 and Jaded, with both male and female vocals capable of triggering it.

That is what made this difficult to catch during a shorter audition. After listening to it over 15 hours it was quite apparent and would show up in unexpected places. I tried tip rolling and Kiwi Ears Flex cleaned it up but not all of it. But I do not want to rely on a particular tip or permanent EQ as typically, the higher the price, the higher the expectation of perfection.

Male vocal sibilance would show up mid listening reducing my overall enjoyment from RSV MK2. This was driven by the 7.2kHz peak.

Technicalities

RSV MK2 is technically very capable. Detail retrieval is strong, layering is clean and separation remains intact even with the substantial bass response.

It is also coherent. Nothing sounds obviously disconnected or out of place. The overall technical presentation works really well.

Gaming

Gaming was less impressive. In COD BO7, the bass could make smaller positional cues harder to pick out once the match became busy. The upper-frequency zing also became more noticeable with scorestreaks, grenades and gunfire going off together. It works, but this would not be my choice if gaming is a priority. You can have a better time using Astral or Arete 2 for close to 220-250$ on discounts.

Fit / Accessories

The shells are large but fit my ears reasonably well and maintained a good seal.

My bigger complaint is the cylindrical case. I did not like how the IEMs sat inside it and replaced it because I was worried about putting unnecessary pressure on the pins.

At this price, I expected a better case design. It does come with IEM pants though. So there is that and a cleaning brush.

Comparisons

Xenns Mangird Top Pro

RSV MK2 has more bass quantity and body.

Top Pro is more resolving, separates better and works much better for me across both music and gaming.

Fresh Reviews Arete 2

RSV MK2 is the stronger music set, especially if bass matters.

Arete 2 is considerably better for gaming, particularly positional accuracy and keeping cues readable during chaos. With bass switch on, it can keep up with RSV MK2 in bass as well (though more sub-bass focused).

Binary Acoustics 1900

RSV MK2 has much better bass, which is the weakest part of Binary 1900 for me.

Binary still wins overall for music because its vocals and upper frequencies are more consistent with my preferences. I can listen to this endlessly.

Juzear Light Shuttle

RSV MK2 has better bass texture and greater overall refinement.

Light Shuttle is the easier all-rounder and performs better for gaming, which becomes especially interesting considering the price difference. It can also show some upper-frequency zing on certain tracks, which I covered in my recent review.

Punch Audio Martilo

RSV MK2 has the more refined bass response and stronger technical performance.

Martilo gives me more outright sub-bass and gets surprisingly close in enjoyment for substantially less money.

Final Thoughts

It is quite important to spend more time with audio products. That is why I clearly call out Audition vs. Ownership in my ranking list. The more time you spend with a product the more you learn about its quirks and how presentation can change for different use cases. RSV MK2 went from an amazing memory to something I could not quite make work after living with it. And at $699, “almost” is not enough. Guess I would need to find something else to Hear The Truth. :). On to the next one!

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Hello! I've made a thing. It makes changing and managing EQ profiles on the CrinEar Protocol Micro, Protocol Max and FiiO KA15 simple and fast using android phone.

You keep a library of EQ profiles on your phone, plug in the dongle, pick a profile and hold to send it. Whole process takes few secounds to complete :). So it's super convinient and easy to use. You can also tune on the go: drag the bands on the graph, fine-tune with sliders.

It only works on Android for now. It's open source (Apache 2.0), and you'll have to sideload the APK (or install it through Obtainium, which also keeps it updated). No internet or account needed, no analytics, no ads, no telemetry, no data retention. I made the app for myself, which is why there's no iPhone release, but if there's enough interest I might look into a port.

Links
Website with the demo and a full video guide: https://chronosauros.github.io/contour
Install guide: https://chronosauros.github.io/contour/install/
Source code: https://github.com/Chronosauros/contour

It works with the Protocol Micro (8 bands), the Protocol Max (10 bands) and now also the FiiO KA15 (10 bands - you pick which of its USER1-3 slots to write to, and the slot gets the profile's name). I tested it on a Micro and a KA15 and community member tested the Max on a real unit, thanks!

The app has been downloaded almost 352 times by now! (the most downloads for a single version was about 82, but still!)

The app has over a week by now, I resolved all issues that were reported and improved features and design. I feel like the app is in a really good shape now. I want to keep improving it overtime :).

For those who care about the process: the app was coded with Claude Opus 5.5, then audited, debugged and cleaned up with various models/services: OpenAI's Astra + Sol, Mimo V2.6 Pro + Flash, and unbiased pareto 26.9. The demo video was also made with Opus 5.5.

If you have any feedback or want to help with the development just reach out!
I know there is some interest in iPhone app - I don't feel that I have enough time or resources to maintain android + iPhone version. But the app is open sourced - so if anyone wants to fork it/port it/ maintain an iOS version - it would be awesome!

Got a different dongle? There's also an advanced beta - a separate app that installs next to the normal one. It recognises about 400 more devices (WalkPlay-based dongles like Tanchjim and TRN Black Pearl, other FiiO models, KT Micro), but most of them haven't been tested yet, so every report helps. Master_Cartoonist_16 already confirmed 7, including the FiiO QX13, TRN Black Pearl and Moondrop Dawn Pro 2 - thank you! Check if your device is on the list: https://chronosauros.github.io/contour/devices/

This is not an official CrinEar app! I'm not affiliated with, endorsed by or connected to Crinacle, CrinEar, Moondrop or FiiO in any way.