DUNU-TOPSOUND DK-4001

Disclaimer
The DK-4001 is a loan sample and has to be returned. No incentive was given for a favorable review. This review is my honest opinion of the DK-4001.

Listening notes
I spent approximately 60 hours with the DK-4001, listening to Cayin N6ii (A01 and T01 motherboard) with the stock Dunu Noble cable and the Hansound Zen 8 wire both using balanced 4.4 plug.

Special thanks
For some reason, I have meant to try a Dunu product for a while now but never blind purchased one as I had very few opportunity to audition the gear even in Paris (this is going to change soon) and it actually was how Dunu set me up with a demo. Kudos to the Dunu team for taking community feedback into account and proactively contacting me to fix that situation. Thanks to Dunu for also helping me make the French Review Tour a reality and provide a sample demo of the DK-4001 and DK-3001 Pro.


Packaging and accessories


The Dunu DK-4001 packaging is quite premium, with a nice and compact leather carrying case. You can also find Spinfits CP145 and Comply tips, airline adapter and cleaning tools.

Worth mentioning is a « stock » cable that is more up to par with a very good upgrade cable as reflected in the price of the Dunu Noble cable (389$) that is provided with the DK-4001. A cable worthy of a flagship.



It’s a high-purity Furukawa Single crystal copper and pure silver braided cable. The cable features the fantastic interchangeable plug system that was found with the DK-3001 and continued with the Dunu Hulk. It come with 2.5, 3.5 single ended (and 3.5 pro balanced) and 4.4 termination. Note that Dunu added an additional interference-killing OCC copper sheath around the wires - a construction rarely ever seen in earphone cables. Interestingly, when I tested the Dun Lyre of the DK-3001 Pro, I noticeably picked up interference when running the N6ii with wifi on.

On top of this Dunu opted for their own patented catch-hold type connectors, « lowering connection instability and pin breakages, and effectively prolonging the service life of MMCX connector interfaces ». Catch-Hold® MMCX connectors are universally compatible with all standard spec MMCX seats which means upgrade cable are of course possible.



Specifications

• Driver Configuration:
  • 4 x Balanced Armature (Knowles)
  • 1 x 13mm Beryllium Dynamic
• SPL : 112dB @ 1kHz
• Impedance: 32ohm
• Frequency Response: 5Hz – 40khz

Fit, Build & Isolation
The DK-4001 fit is one of the best I have had with an universal IEM, it small, lightweight and ergonomic. The DK-4001 is one of a short list of IEM with a Zirconium shell, like Sony IER-Z1R. The use of Zirconium « effectively suppress harmonic resonance » according to Dunu.

Design wise, I like that the nozzle has a small ridge line to allow for deeper tip insertion, I didn’t need it but it can come in handy and reflects the ergonomic focus in the DK-4001 design. Included spinfits are really good and I didn’t need to do any tip rolling with my own tips. The over the ear cable configuration with preformed hook makes wearing the DK-4001 very secure. Isolation is good thanks to deep insertion and as usual for best results comply tips provide additional isolation.



Introduction
Dunu is now a well established brand in the audiophile world, which started as an OEM for famous brands. Since 2014, Dunu built its own IEM and now has a fairly complete lineup of dynamic and hybrid IEMs (Titan series, DN and the top DK series). After launching the DK hybrid series in 2015, Dunu set out to design the most compact, optimal shell fit that would define our flagship series. The DK-4001 says it has taken their head engineer Andy Zhao three years refining the acoustic formula, going through several redesigns before settling on its current form.

Dunu states : « We used two Knowles in tandem for four drivers in total, giving the DK-4001 the ultimate in treble headroom, and allowing its bandwidth to extend all the way beyond 40 kHz. To dial in the ideal balance between detail and harshness, we spent two months alone adjusting the tubing diameters, lengths, and damping materials, as well as the ideal crossover point for these tweeters. The result is a rich, luxuriating treble response pegged right where we want it to be. » About the dynamic driver, they state : « This 13mm speaker retains the speed and rigidity of a pure Beryllium cone, reproducing the kind of realistic timbre and wide staging that audio lovers crave. We allow it to sing freely by letting it take over the entire audio spectrum all the way to the low treble, reproducing music truly the way it was meant to be heard. »



The product page on Dunu’s website doesn’t expand too much on the DK-4001 tuning except from exceptional bass control deriving from Zirconium properties and the acoustic design through their patented ACIS which is a spiral design pathway : « To take full advantage of the speed and dynamics of the Beryllium driver, we wanted to take on the challenge of integrating a bass reflex system normally found only in home speakers. After long hours and endless trials tweaking its length and size, the resultant, labyrinthine Air Control Impedance System (ACIS), was born from an obsession that nearly spiraled out of control. The end result is a spectacular bolstering of frequencies under 80 Hz while still retaining depth and agility. »

Clearly, Dunu invested a lot into the design of the DK-4001 : materials with the zirconium, acoustic design with ACIS and tubing and damping of the Knowles drivers, coating of the beryllium driver. How does that translate in terms of sound quality? Let’s see !




Sound
The very first minutes into auditioning the DK-4001, the first thing that came to mind was how good the bass was, as in definitely top tier good : Dunu certainly has found a superb balance between engagement and technicality there. The second thing that came to mind was that detail retrieval : very very good, but maybe a tad over accentuated upper treble for my taste reaching the edge at times on some recordings. Not unforgiving, just a tad to present upper treble peaks for my taste and limiting the naturalness of the DK-4001. This was even more apparent with the T01 motherboard for the N6ii so I kept the A01 on for the rest of the review.

I began suspecting the silver in the Dunu Noble cable was maybe not in the line with my personal preferences and despite its stunning build and fantastic form factor I should try something different. Unfortunately my Dunu Hulk is 2pin so I couldn’t test that. I swapped the Dunu Lyre which is also a full copper and… the result was much more in line with my personal preferences. I found the DK-4001 gained musicality and didn’t have any peaks in the upper register as well. Sure, the Noble provides greater detail retrieval but to me at the cost of too much upper register emphasis, taking the attention away from a beautiful midrange. I then tried on a Hansound Zen full copper 8 wire cable and… the DK-4001 soundstage expanded to holographic territory with better imaging and layering. Obviously your mileage may vary and not everyone has the same preferences. This speaks to the scalability of the DK-4001 as well, which shows that it has great potential to fit your personal preferences.

The soundstage is not massive like say Campfire Solaris but it’s pretty good nonetheless, quite wide and fairly deep but not very tall. The image is not congested and remains articulate but separation is not accentuated, the image is more of a continuum while not falling into the wall of sound category. Vocals and lead instrument are clear and distinct, but not significantly forward either. Note attack is snappy and decay is very natural.

I didn’t find the DK-4001 hard to drive and the N6ii was set on low gain at fairly moderate level (35-50/100). I suspect though that the DK-4001 could reach yet another level with an amp, I see the DK-4001 having good scaling potential with its 32ohms impedance and dynamic drivers usually like power.



Bass
Note : The DK-4001 bass was great right out of the box but got even better with burn in with things settling in nicely after 40 hours or so. The main benefit is tighter bass with better control as the beryllium driver settles in.

The DK-4001 bass shows that Dunu’s R&D and work on acoustics of the shell (ACIS), optimized resonance with Zirconium and driver coating certainly paid off as advertised on their product page. The bass extends deep and exhibit fantastic control with very low resonance indeed. This is especially stunning on sub bass : there is plenty of subs but close to no distorsion whatsoever the subs are as clean as I have heard them.

This results in one of the best if not the best portraying of bass I have heard to date. This is an experience not unlike the legendary Sony EX-1000 with bigger than life bass that sure rarely belong in an IEM but rather in good closed back full sized headphones and not often with that level of control. Impressive if you factor in that it’s faster than the EX1000. Mid bass have great slam factor and remain clean and controlled whatever I threw at them. Despite its relatively big size (13mm) the beryllium dynamic driver is quite fast with quick decay and recovery time, providing a very good sense of pace.

The DK-4001 bass make the DK-4001 a very engaging listen, bass guitar have good weight, kick drums have such a satisfying, toe tapping punch and there is a physicality from the subs that make the DK-4001 a very powerful IEM that almost sounds like a full sized headphones.

This is class leading bass performance with a touch of basshead pleasure, although I don’t think pure bassheads will find the quantity to be enough. Dunu strived to keep the DK-4001 in the flagship category meaning it shows proper restraint and does not overdo it. But you can feel that given the right source, right EQ and right cable the driver probably has basshead potential for those who would want to go down that route.

Mids
The DK-4001 mids are not as warm as those featured on the DK-3001 Pro and more in line with what you would expect from a flagship : natural sounding with good tonal balance and articulate image.

Given the strong bass presence Dunu wisely kept the lower mids on the leaner side gently rising from 600Hz and topping a little before 2kHz. For the same reason given the treble presence, Dunu rolled off the upper mids from 2kHz to 4kHz where it reaches its lower point and then a rise to plateau at 6kHz up into the treble section. Clearly, the mids presence is derived from the 1-2kHz range. This results in mids that give instruments a slightly forward placement but avoiding too much excitement, attack on percussive and rhythm instruments is on the softer side.

The DK-4001 excitement is focused on its bass and treble but the fairly neutral mids are placed a bit forward to balance the overall frequency range and avoid a U shaped signature. A wise choice as too much lower mids would have resulted in a warmer signature (aka DK-3001 Pro as we will see in an upcoming review) and too much upper mids would have made the DK-4001 a very fatiguing IEM. On the flip side, this affect the bass guitar snap, the saxophone bite or energetic cymbals « clang » for example.

Treble
It’s very clear with the DK-4001 that Dunu aimed at a different goal than the more « mainstream » (this is in a good sense) DK-3001 Pro. Flagship often equates to resolution and definition, by way of more upper treble presence among other things. I believe this also explains the choice of a copper-silver mix in the Dunu Noble cable that comes stock with the DK-4001. As I hinted before, this clearly boost the upper treble section and make the DK-4001 detail retrieval greater but it also was a source of frustration to me as it kind of broke the naturalness of the upper register. For the rest of the review, I alternated between the full copper Dunu Lyre and the Hansound Zen 8 wire that both brought a more natural tone and smoother treble presentation.

The DK-4001 has good lower treble energy with a 6 to 8kHz plateau, snare drums have a satisfying snap and Piano, hi hats and cymbals have nice overtones that contribute to the musical engagement the DK-4001 provides. Despite the energetic lower treble, the DK-4001 manages to remain smooth and never harsh. Treble tone is accurate, and the note weight is quite balanced it’s neither a full bodied nor a feather like treble but rather very natural sounding notes.

Upper treble roll off steeply between 8 and 10kHz with a steep rise past 12kHz up to a 20kHz peak. The DK-4001 has good resolution and air and never feels congested but to me it’s not up there with the best here in terms of sheer resolution and refinement.


Verdict
The first contact with a brand is usually a good way to measure the quality of their product and upon my contact with the Dunu Hulk I was very impressed that a 300$ cable was built better than some products 3x as expensive not even taking into account the fantastic interchangeable plug system. It was just as impressed with the DK-4001 from the unboxing to the superb build and cable and the great fit.

In the very competitive hybrid universal landscape, the DK-4001 stands proud as a proper flagship product the Dunu brand packed a lot of R&D into : zirconium shells are notably hard and costly to produce (and featured in much pricier IEMs), driver coating process, and acoustic research (ACIS, tubing, damping...) clearly paid off especially in the bass department. The effort was furthered by packing the best build on a stock cable I have ever seen in a product and a very rare instance on the market (aside from LCD-i4, I don’t know of other examples of such premium stock cables).

All in all, you’d be hard pressed to find a competitively priced hybrid that packs as much R&D and premiums materials and cable, bar the Sony IER-Z1R priced over twice the DK-4001. This tells you something about Dunu’s commitment to grow their product range.

If you’re looking for a hybrid with superb build and cable, class leading bass (I am thunderstruck!) that is both fun and technically faultless, natural mids with slightly forward vocals and lead instruments and exciting treble then you’d be hard pressed to find a better alternative than DK-4001 for the price!

If you’re willing to sacrifice a bit of bass control, overall technicalities and like a warmer tone and smother presentation then its little brother the DK-3001 pro is definitely an alternative worth looking at. If you’re willing to spend a bit more, the Rai Penta will be airier with greater soundstage and imaging but you won’t get the satisfying bass experience or the body and weight you’ll get from the DK-4001. You could also satisfy your inner basshead and go to Campfire Solaris to enjoy massive soundstage, subwoofer like sub bass and sparkly lower treble but you won’t get the same control and balance as the DK-4001. In the technically proficient category, you could get a look at StealhSonics U9 to get further refinement in the upper treble section and more detailed mids but you would miss out on the incredible DK-4001 bass experience and you wouldn’t get the same bodied presentation.

I must say I am very eager to see what Dunu will come up next with the DK-4001 Pro and any other product for that matter!

Nuance and Finesse - Dunu DK-4001 IEMs & Dunu Hulk Cable Review

Dunu DK-4001 is the current flagship from the Chinese company Dunu, and it is a total innovation from their previous model, the DK-3001, as it has a much better ergonomic, cool aesthetic, and a good amount of tips and accessories. Dunu Hulk also makes an intro in this review, as Audiophile-Heaven expands with more cable reviews. DK-4001 is priced at 900 USD, so the main competitors for DK-4001 are HIFIMAN RE2000 Silver, Lime Ears Model X, and Campfire Atlas.


Introduction

Dunu is one of those companies from China that didn't want to set out to make just cheap products, but didn't want to make them as expensive as possible, so instead they dedicated and set out to create some of the best build quality, best overall package, and just overall great sound and products. It is interesting to note that they do provide good aftermarket service, and that they do not disappoint in any aspect with their products, and to date, are one of the most reliable Chinese IEM companies.

It should be noted that I have absolutely no affiliation with Dunu, I am not receiving any incentive for this review or to sweeten things out. I'd like to thank Dunu for providing the sample for this review. This review reflects my personal experience with Dunu DK-4001 & Dunu Hulk. Every opinion expressed is mine and I stand by it, the purpose of this review is to help those interested in Dunu DK-4001 & Dunu Hulk find their next music companion.



About me

https://www.audiophile-heaven.com/p/about.html



Packaging

First things first, let's get the packaging out of the way:

I have some talk to do here, because for the first time in a while, we get a nice looking package that has enough extras to give us something to play with. Starting with DK-4001, there is a plethora of tips included, and the best part is that some of those are actually spinfit tips, but those are a special selection made just for DK-4001.

Furthermore, you may notice some odd-looking jacks inside the package, and unless you read another review, those won't make much sense, but the short version is that both DK-4001 comes with a fully modular cable, and Dunu Hulk itself is a fully modular cable. This means that you don't have to keep changing the cables every time you want to go from a single ended source to a balanced one, or between different sizes of balanced cables, like going from a 2.5mm to a 4.4mm output.

This makes comparing different sources much easier, and also makes the entire process of owning high end IEMs and headphones more fun in the long run. There is also a carrying case included with DK-4001, and that's just the little accessory on top of the entire already great package.









Dunu Hulk also comes with those modular jacks, so you don't have to worry, the first cable made and sold standalone by Dunu has all the perks of other Dunu products.



What to look for when purchasing a high-end In-Ear Monitor

https://www.audiophile-heaven.com/p/what-to-lookl.html



Build Quality/Aesthetics/Fit/Comfort

Starting with the build quality of DK-4001, you will quickly notice that there is a huge difference between it, and the DK-3001 IEM which I reviewed in the past. The difference is not in the build quality itself, actually, as both are really well built IEMs with high-quality cables and with good comfort, but there is a large difference in how each of them fits in your ears, with DK-4001 being considerably more comfortable than DK-3001, due to longer bores, and to a much more ergonomic design. The MMCX connectors are also much better, since the cables can be removed and the cables will not turn freely inside the socket, compared to the original DK-3001 where multiple reconnections of the cable did loosen the connector and lead to a less reliable IEM in the long run.

The aesthetics of the DK-3001 are pretty spartan and basic, with a slightly industrial, yet modern looking IEM greeting you. It is accompanied by a thin and flexible cable, and DK-3001 has a larger vent on the outer plate, along with a smaller vent hole on the inside. Since DK-4001 has 4 BA drivers and one Dynamic driver, it needs good ventilation so that you won't feel any driver flex, and Dunu manages to deliver quite well on that, and you feel no flex with DK-4001.

Furthermore, with DK-4001 you also get no cable noise, or microphonic noise, and you get a really comfy IEM, thanks to its very ergonomic and well rounded design with no hard edges and thanks to a bore tube that is long enough to reach a comfortable fit with your ear.

The other thing you should be glad you have with DK-4001 is the large selection of tips, which include spinfit tips, along with foam tips from comply and with a few unbranded silicone tips, so that you can eventually get the best fit you could dream about with it. The selection of tips changes the sound, as with every IEM, and I found the best sonic / comfort balance with spinfit.

DK-4001 offers mediocre isolation from the outside noise, since it has quite a few ventilation ports, but it offers one of the best comforts I have had with a IEM, making me desire to wear it more and to use it more.

Now, the cable. Dunu Hulk, is another story entirely, because it is not the same cable as the cable that DK-4001 comes with. Dunu Hulk is a much thicker and less flexible cable, and if you ever wanted to have a cable that feels thick and high-quality, Hulk surely won't break regardless how much you beat it around and use it. Not just that, but Dunu Hulk tends to be one of the most resilient modular cables on the market at this moment, relying on the same mechanism as DK-4001, so you know their best tech went inside both the IEMs and the standalone cable.

Overall, we have an ergonomic, comfortable and reliable IEM, and a thick, slightly rigid, but very resilient cable with DK-4001 and Dunu Hulk.



Sound Quality

The sonic performance of DK-4001 is what I would call a mixed coup. The fact is, the sound itself is really really good, but it mixes things to such a degree that it is a bit hard to put in words, compared to a more traditional IEM like DK-3001 or Falcon-C, both of which had a pretty usual V-shaped and neutral signatures. With DK-4001, you get a high emphasis on the bass, and especially the sub-bass, a strong female performance, along with a solid male performance, but with a smooth and relaxed top end that's smoother than you'd expect from a IEM made by Dunu, especially if you heard or will hear any of the other IEMs designed by them. Uncharacteristic of them, DK-4001 is actually soft and musical overall, despite the bumps and dips in the frequency response graph. It surely is not a very exciting presentation and won't get you up all night, instead softly tickling you with a forgiving presentation that you will want to lean on for hours in a row.

The bass delivers an impact that I've yet to see on many IEMs, with no roll-off even at 20Hz, so you get the extension you always dreamt of. There is a good articulation and excellent speed, and although DK-4001 is far from being a basshead IEM, the bass could be considered its strong point. There is good weight to each musical note, and there's also a pretty linear overall extension up until 600 Hz, after which there is a bit of a dip that goes down a gentle slope.

This being said, Dunu didn't go for the typical dip in the midrange that would have made DK-4001 a pretty typical V-Shaped IEM, and instead the voices are pushed pretty forward, and the textures are what I'd call soft to very soft, with nothing being aggressive, and sacrificing some clarity and punctuation in every sound, for a better understanding and expression of nuance. The midrange is tied pretty nicely to the bass, since the 13mm driver Beryllium driver takes care of both the bass and the midrange, making DK-4001 pretty coherent in terms of overall decay and speed. The soundstage is not large, nor wide, but it has good depth, providing a very well-rounded performance, and a pretty nice kick for those who wanted to feel as if they were in the same room as the singer, but who still wanted to have a good sense of depth and distance between the instruments.

The treble is rising up until 7kHz, after which it starts rolling off and out. The fun part here is that the entire IEM doesn't get to sound dark or thick because of this, but DK-4001 stays within what I'd call neutral, yet soft and musical, truly a tuning I haven't heard any other IEM going for to this date. If you've worked in music mastering before, I would call DK-4001's sound wet and non-fatiguing rather than dry or edgy, as the treble avoids any harshness or aggression in music, without getting heavy, thick or bassy.

Dunu Hulk, as a cable, is pretty much at the other end of the spectrum, and it tends to sound smoother, warmer and more creamy than most stock cables, and especially when you pair it with bright and thin sounding IEMs, you get a heavenly match.



Portable Usage

Given the pretty low impedance of 32 OHMs and the 112 dB SPL, DK-4001 is easy to drive and will pair well with any source, although it does tend to suck more juice from your source than most IEM hybrids. This means that you end up turning the volume higher, which could lead to some hiss if you had a hissy DAP like Hiby R6, but you'll hear almost to truly no hissing with more tame DAPs like DX220 and FiiO M11.

DK-4001 is best complimented by a DAP that sounds more articulate, and is not very well complimented by softer DAPs like QLS QA361, since DK-4001 is already pretty soft. This being said, the soft cable, good ergonomics and fair noise isolation will make you want to take DK-4001 quite often with you, and just plug into your phone, and hope for the best. In this situation, I always recommend using Roon if you can, because you get a selection of DSPs that could help match IEMs like DK-4001 with a sub-par source like a smartphone better.

Dunu Hulk, on the other hand, is what I would call technically portable. It is portable, it has very solid connectors, very solid build quality, it has no microphonic noise and also makes for a beautiful cable, but at the same time it is rigid for an IEM cable, and I would probably have considered it a 10/10 headphone cable, rather than a headphone cable. Furthermore, with Hulk you get a rather heavy cable for IEMs, which isn't entirely practical, but, at least it makes for an excellent cable upgrade for 300 USD if you wanted something that does look more reliable. If you ever had a Sennheiser IE800, you may be acquainted with the cable hardening issue, and you will also be happy to know that Dunu Hulk does not suffer from such issues and it is a pretty much perfect cable.

The other little magic part with both DK-4001 and Hulk is in their modularity, as both can be connected to a selection of sources, both single ended, and balanced, even the newer 4.4mm balanced port, as well as the 3.5mm Balanced 4-pole connector that HIFIMAN DAPs, as well as a few others use.



Comparisons

As promised, the comparison list is fierce, with HIFIMAN RE2000 Silver, Lime Ears Model X, and Campfire Atlas being very pertinent competitors for an IEM that costs 900 USD. Each one of those is pretty similar in terms of price, or at least close enough to make the comparison interesting.



Dunu DK-4001 vs HIFIMAN RE2000 Silver - The package is better for DK-4001, and so is the default cable, which is modular for DK-4001 and normal for RE2000 Silver. The comfort is good for both, and both offer similar passive noise isolation. Both are similarly easy to drive and both are similar in revealing how hissy a source is. I have been using RE2000 Silver with Spinfit tips, which need to be purchased separately, while for DK-4001, you get them inside the package. When it comes to the sound, though, it is quite different, with RE2000 Silver being very textured, analytical, detailed, and much more aggressive and engaging, while having a similarly sized soundstage as DK-4001, but DK-4001 having a much softer, more easy sound, despite having a similar tuning and similar overall macro detail level. Both are quite interesting, but if you're into a lot of rock and metal, the textures of RE2000 Silver may compliment your music more, while if you're into Jazz or easy music, DK-4001 should compliment it more.

Dunu DK-4001 vs Lime Ears Model X - Lime Ears Model X is that one IEM that has two sounds, as it has a physical switch that changes its signature from a colder more analytical one, to a warmer, larger and more enthusiastic one. This means that regardless of the position that switch is in, you get two signatures that are different from the soft and neutral-ish signature of DK-4001. In terms of comfort, DK-4001 is much more comfortable than Model X, which is larger, has a cable with hard memory wire around the ear, and which just doesn't sit quite as comfy compared to the ergonomic DK-4001. The body of DK-4001 is also considerably smaller. This being said, Model X does not have any driver flex either, and they do offer better passive noise isolation. The default cable is way better on DK-4001 and I would recommend upgrading the cable of Model X if you decide to go for it, with something like Dunu Hulk, as they pair really well together.

Dunu DK-4001 vs Campfire Atlas - Campfire Atlas is one of the more pricey competitors for DK-4001, and after hearing it, you immediately know why, as it provides a very large and grandiose presentation, although if you like its sound, you probably aren't looking for the character of DK-4001 to being with. In terms of packaging, the carrying case of Atlas is better, and the cable is softer and more flexible, but the cable of DK-4001 makes a much better overall cable if you have multiple sources, especially if you have both single ended sources and balanced sources. If you like comfort, DK-4001 is more comfy, has no driver flex, while Atlas does have driver flex. DK-4001 also sits more comfortably in the ears and feels more secure while walking and doing activities. On the other hand, in terms of sound, you really will go for one or the other, Atlas is very much a V-Shaped IEM with a strong taste for bass, sounding huge and having a huge stage, while DK-4001 is much more of a close friend, intimate IEM that's made to sound soft and musical, non-aggressive and easy on the ear, all while keeping a good degree of neutrality.



Recommended Pairings

In terms of pairings, I have chosen iBasso DX220 featuring AMP 9, Mytek Brooklyn DAC+, and FiiO M9, all of those being pretty interesting DAPs to pair with your DK-4001

Dunu DK-4001 + iBasso DX220 (AMP 9) - When you pair DK-4001 with a pretty detailed and lively source as DX229, you get a very nice final result, because the mellow and soft character of DK-4001 is complimented by DX229, you get a more vivid midrange presentation, a larger overall soundstage than the average, and you also get a very good amount of detail. This being said, you also get access to Tidal, Streaming services, as many as you could desire, and the ability to connect more headphones and IEMs to DX220, as it has enough driving power even for most full sized headphones. There is no trace of hissing, and overall, this is one of my top choices if you can afford it, especially for a portable.

Dunu DK-4001 + Mytek Brooklyn DAC+ - There is a good reason to include a high-end desktop DAC/AMP in this pairing, because many want to know if DK-4001 will make sense when you get home and forget the noise of outside as well, and well, it still is a very relevant IEM. Mytek Brooklyn DAC+ tends to be a very wide and well-rounded DAC/AMP, with a huge holographic soundstage, and DK-4001 surely is complimented nicely by it, getting a much wider and more relaxed, expanded sound. There is better layering than with most sources, and the detail is also really good. This being said, the mellow and soft character of DK-4001 is not lost, and it doesn't get aggressive, and if anything, the pairing is quite musical, yet a touch more exciting and engaging than when pairing DK-4001 with the average source.

Dunu DK-4001 + FiiO M9 - With FiiO M9, you get a very good portable DAP, that's based on FiiO's engineering design, with enough power to drive most portables, but also a sound to match its price. M9 is pretty pocket-friendly, and you get a very soft and docile presentation with DK-4001, and if you wanted to experience the more intimate, gentle, soft, yet very neutral sound of DK-4001, then M9 is one of the best DAPs to pair it with.



Value and Conclusion

The value of Dunu DK-4001 is a bit questionable, as it is a flagship, high-end IEM, and it isn't exactly a cheap option, instead actually being a pretty pricey IEM. This doesn't mean it isn't good, it just means that you should chose it if you're going for its precise signature, as it has a very specific tuning, and it is not quite a whole-purpose IEM like other flagships are. It does have some aces up its sleeve, like the amazingly handy modular cable, Spinfit cables included in the package, and the nifty carrying case and premium package it comes with, making it a very good option.



Dunu Hulk is also pretty fair in terms of pricing, especially for a high-grade cable, but it is a bit more than most expect or imagine paying for a cable at this moment, especially if you're new to purchasing aftermarket cables. On the other hand, if you're a seasoned IEM user and have had your share of experiences with cables, you will know that for a fully modular cable, Hulk is just right in terms of pricing, especially if you have a brighter or harder to tame IEM that you always wanted to sound warmer, more rounded, and more creamy.

The package of DK-4001 is very all-inclusive and so is the build quality, which this time has both excellent build and excellent ergonomics, making DK-4001 one of the best IEMs I have served to date in terms of comfort, coming close even to the mighty HIFIMAN RE800 Silver, which barely makes any contact with your ear, so it is inherently comfy. DK-4001 is so well designed, it gets even better than that. No microphonic noise, and no driver flex also lead to a good comfort with DK-4001.

If you're looking for a softer, more mellow sound that has a quick and well-bodied bass, but which doesn't feel aggressive in any way, and will give you an intimate moment with your favorite singer, you will probably fall in love with DK-4001.

Also, if you're looking for a solution to make your IEMs sound more creamy, a touch warmer, more rounded, and more musical, Dunu Hulk has a sound that will surely improve your listening sessions.

At the end of this review, if you're looking for a high-end IEM, with good build quality, comfort, ergonomics, a soft, mellow, yet quick sound, with a slightly intimate stage, and which comes with both a modular cable and spinfit cables, you should totally consider DK-4001 as your next IEM purchase.



Full Playlist used for this review

While we listened to considerably more songs than those named in this playlist, those are excellent for identifying certain aspects of the sound, like PRaT, Texturization, Detail, Resolution, Dynamics, Impact, and overall tonality. We recommend trying most of the songs from this playlist, especially if you're searching for new most, most of them being rather catchy.

Youtube Playlist



Tidal Playlist

https://listen.tidal.com/playlist/64555551-ec3c-4279-ae44-248fdfcf6c4b

Song List

Bats - Gamma Ray Burst: Second Date
Eskimo Callboy - Frances
Incubus - Summer Romance
Electric Six - Dager! High Voltage
Kishida Cult - High School Of The Dead
Dimmu Borgir - Dimmu Borgir
Breaking Benjamin - I Will Not Bow
Thousand Foot Krutch - The Flame In All Of Us
Gorillaz - Feel Good Inc.
Infected Mushroom - Song Pong
Attack Attack - Kissed A Girl
Doctor P - Bulletproof
Maximum The Hormone - Rock n Roll Chainsaw
Rob Zombie - Werewolf, Baby!
Escape The Fate - Gorgeous Nightmare
SOAD - Chop Suey
Ken Ashcorp - Absolute Territory
Machinae Supremacy - Need For Steve
Ozzy Osbourne - I Don't Wanna Stop
Crow'sclaw - Loudness War
Eminem - Rap God
Stromae - Humain À L'eau
Sonata Arctica - My Selene
Justin Timberlake - Sexy Back
Metallica - Fuel
Veil Of Maya - Unbreakable
Masa Works - Golden Japang
REOL - Luvoratorrrrry
Dope - Addiction
Korn - Word Up!
Papa Roach - ... To be Loved
Fever The Ghost - Source
Fall Out Boy - Immortals
Green Day - Know The Enemy
Mindless Self Indulgence - London Bridge
A static Lullaby - Toxic
Royal Republic - Addictive
Astronautalis - The River, The Woods
We Came As Romans - My Love
Skillet - What I Believe
Man With A Mission - Smells Like Teen Spirit
Yasuda Rei - Mirror
Mojo Juju - Must Be Desire
Falling Up - Falling In Love
Manafest - Retro Love
Rodrigo Y Grabriela - Paris
Zomboy - Lights Out
Muse - Resistance
T.A.T.U & Rammstein - Mosaku
Grey Daze - Anything, Anything
Katy Perry - Who Am I Living For
Maroon 5 - Lucky Strike
Machinae Supremacy - Killer Instinct
Pendulum - Propane Nightmares
Sirenia - Lithium And A Lover
Saving Abel - Addicted
Hollywood Undead - Levitate
The Offspring - Special Delivery
Escape The Fate - Smooth
Samsara Blues Experiment - One With The Universe
Dope - Rebel Yell
Crazy Town - Butterfly
Silverstein - My Heroine
Memphis May Fire - Not Over Yet

I hope my review is helpful to you!

Dunu DK-4001 Chi: Perfect Fusion

A reputable IEM brand, Dunu finally came up with the long-awaited product - the DK-4001. It's been delayed a lot more than we expected and there are good reasons behind it. We'll be going through about these stories as we progress with the review. DK-4001 is Dunu's current flagship model retailed for $899.

Packaging

The packaging has gone through some changes too, now coming with a high-class packaging and presentation. As you open the box, the first layer is covered with a protective sheet, containing the earphone, stock cable, and 2.5mm / 3.5mm balance / 4.4mm jacks.

The second layer contains a leather case, aircraft plug, 6.35 plug, cleaning brush, 4 pairs of Spinfit tips, 3 pairs of silicone tips, 1 pair of Comply foam tip, and a leather case, and two paper works that describes the specs and tech behind the product, each written in English and Japanese.

Earpieces - Design

The earpiece shape of DK-4001 has a similar form factor as the DK-3001, though a whole lot more ergonomic. The nozzle length and angle have been adjusted, providing a more secure fit. The inner part of the shell has been modified, now having a smooth and simpler round shape which sits comfortably in the ears without a problem.

It has been an ongoing topic throughout the communities that DK-3001 were uncomfortable and saw many who had to give up using them for its problematic fit. While I personally haven't found the fit to be an issue from it, without a doubt DK-4001 provides a better fit as well as a deeper insertion. The housings are made of zirconium liquid metal alloy, just as the Falcon-C does. The MMCX connectors also seem to be replaced with new generation sockets, providing a stronger yet durable connection.

Earpieces - Drivers

DK-4001 features 4 BA drivers and a single 13mm beryllium dynamic driver, both sides coated with PVD. I've found it interesting that these, having 4BA+1DD configuration, are set to be only 2-way. Turns out the dynamic driver covers from ultra lows to upper mids, while all four BA drivers are tuned to work as super tweeters for high frequencies. It's pretty much a dynamic driver powered IEM, augmented with multiple BA drivers.

For a little more elaboration, dynamic drivers make sound by vibrating the diaphragm. Though this easily results in an issue where the middle and the edge of the diaphragm start to show differences in frequency production. Manufacturers overcome this issue with various solutions (Hifiman's Topology diaphragm, AZLA's Infinity ARD, Campfire Audio's ADLC diaphragm, etc..) and Dunu decided to solve this by substituting in with BA drivers instead.

Dunu also applied a spiral-shaped vent path in the inner part of the faceplate which could achieve deeper bass response low as 80Hz. Enough with the talks behind the product, let's now talk about the actual stuff.

Cable

The cables got more serious too. It's stranded with 7N copper and pure silver wires with a modular plug system, Quick Switching Connector. Dita was first to apply such feature with the Awesome Plug, though convenience is the difference.

Dunu's Quick Switching Connector

Dita's Awesome Plug required screwing in and out for replacing connectors, however with this one you simply pull it out for detaching and push it in for installing. It's significantly faster and it doesn't detach on its own either. I also like that they've included a variety of jacks, including the 4.4mm and 3.5mm balanced terminations.

Sound impression - Lows

Strike and decay are fast and leaves only a minimum amount of reverbs, just enough to maintain the natural representation of the bass. Though this happens along with the ultra-lows being clearly visible, making the overall bass very dark in color without bloating the quantity. The bass feels like it has been matured from a distance until arriving at the ears, presenting a natural sound flow. DK-4001 proves it well how to create heart-rumbling bass without excessive quantity. I'm sure it would be hard to find such clean ultra lows without boosting the quantity.

Sound impression - Mids

The bass extension was amazing, but the real amazing part happens from the mids - it retains much of the characteristics from the dynamic driver while bits of BA characteristics "submerged" into it. It's a new type of characteristics and presentation, so it's quite hard for me to exactly elaborate the feeling.

This perfectly fused hybrid system even left me confused for the first several minutes auditioning to DK-4001. There's barely any gap or sense of difference found between DD and BA drivers. AZLA-01R also done a great job fusing BA & DD by incorporating Dynamic Motion's 'Bull's Eye Driver', but DK-4001 goes even further with the driver numbers, as well as achieving superior excellence, maturity, and performance. Definitely a new experience.

Characteristics, textures, and tonality of mids are mostly dominated by the dynamic driver. There is a glimpse of BA-ish texture and feel from the upper mids but doesn't fall much apart from DK-4001's mainstream tone - in fact, this is the usual Dunu coloring that they slightly add to their most IEMs. Sounds crunchy and resolving, but doesn't fall behind in tonality that much. Mids are slightly placed forward and feel energetic. Compared to DK-3001, it has a wider sound flow and shows significant improvement in resolution. Sibilance is fairly well controlled.

It occasionally makes a slight hiss on the upper mids but doesn't get too sharp or spiky. While it isn't too harsh, this still means that users who are into fatigue-free sound are out of luck. This is something that adds a resolving characteristic to the mids and shouldn't be an issue if you're relatively used to bright sounding IEMs (similar or slightly lesser than DK-3001). Vocals have neutral thickness but tilt a bit to the thicker side.

Sound impression - Highs, etc.

Trebles go for similar characteristics as the mids - shiny, bright, and resolving. Though the reverbs from the treble have been controlled with faster decays, so it doesn't get much hot or irritating. Plus, the soft texture from the lows and the dark background neutralizes the bright, shiny upper frequencies. Trebles have more airiness and approach closer to the ears. Soundstage and imaging definitely head for the flagship level, leaving no doubts with its superiority compared to the DK-3001. Not only the wideness and the 3D presentation has been improved, but also the depth.

Eartips / Cable matching

Dunu spent lots of attention on their cable and eartip selections. The included Spinfit eartips are specially optimized for DK-4001 in terms of both comfort and sound. These eartips have wider bores and slightly shorter stems, less interfering the original staging and bringing the mids a lot closer than ordinary silicone eartips. I usually prefer JVC Spiral Dots as my eartip selection and also did with my DK-3001, though these customized Spinfits provided the best matching among all. Cables are also well matched with these earphones, not lacking in performance compared to other quality custom cables. Copper cables seem to show the best combo and I'm sure Dunu's Hulk cable will work fantastically with these.

Verdicts

DK-4001 is a precisely constructed IEM upgraded from DK-3001 in all aspect. It's interesting to see Dunu applying all kinds of unique structural tuning to create this IEM, but of course, it was to aim for the best and I could also agree to that. It's evident on the product that they've done their best to create a seamless product, starting from the sound to minor details like switchable plugs and customized spinfit eartips. DK-4001 would fit well for those who are looking for a rich w-shaped sound with shiny upper frequencies and would, of course, be a perfect choice for prior DK-3001 or Falcon-C users. Well done, Dunu!