DUNU ZEN PRO

Single dynamic driver flagships are making a comeback, and Dunu’s Zen Pro are the latest entry into the crowded market. The Zen Pro, as the Pro moniker suggests, are intended as an improved version of the original Dunu Zen (now discontinued).

For the Zen Pro, Dunu has altered the housing color and changed the stock cable to a more pliable one. Moreover, they re-engineered the magnet system and re-tuned the driver.

So how well can the Zen Pro compete against their peers? Read on.

The Zen Pro were sent courtesy of Tom at Dunu as part of a review tour.
Sources used: Lotoo PAW 6000, Questyle CMA-400i
Price, while reviewed: $900. Can be bought from Dunu's official store.

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Packaging and Accessories​

The review tour unit came without any retail packaging. You can take a look at my unboxing of the original Dunu Zen since the packaging is similar in terms of design and accessories, apart from the cable.

However, the star of the show is their CHORD cable.

The CHORD is a 4-core cable in Litz configuration with mixed-strand Furukawa OCC Copper and Neotech Silver. Both of the raw materials suppliers are some of the most highly regarded in the industry, so clearly Dunu did not skimp on cost. In addition, the cable is equipped with their patented Quick-Switch modular plug system.



Dunu also supplied the Digital Q-Lock Plus connectors with Type-C and Lightning connections. These act as mini dongles so you can just plug-and-play from the USB-C port on smartphones.



While convenient, I found the sound of the digital connectors to be compressed and lacking in dynamics. These connectors are great proof of concepts but won’t replace a dedicated DAP or a good dongle.

Design​

The Zen Pro have 316L Stainless Steel shells with a glossy Titanium-colored finish. There is one vent near the nozzle while the back of the IEMs have the ACIS vent that is used to control airflow inside the driver housing. The nozzle is fairly long and has a raised lip and metal mesh.



The mmcx connector has Dunu’s patented catch-hold mechanism for more reliable connection. The shells feel positively dense in hand and are designed well. The biggest issue is the glossy finish that attracts smudges and fingerprints.

Comfort and isolation​

Comfort is good for me with a snug fit. The weight is mostly manageable. Isolation is average due to the vent on the back of the IEMs.

Internals​

Dunu debuted a new driver system with the OG Zen that goes by the ECLIPSE trademark. This system doesn’t necessarily indicate the diaphragm material rather how the dome, driver surround, and voice-coil attachment process is executed.

The Dunu Zen Pro have a variation of the ECLIPSE system with a 13.5mm dynamic driver system with a Magnesium-Aluminium (Mg-Al) alloy diaphragm where the micro-pores on the diaphragm surface have been filled with nanoDLC to increase surface stiffness. The driver also has a W-shaped dome, similar to the Focal Clear driver. The diaphragm material has similarities with the Clear as well.



The ratio between the metals in the alloy was adjusted, resulting in a stiffer, lighter diaphragm with higher internal damping and widened bandwidth in the high frequencies. The biggest issue of the OG Zen was their lack of treble extension and the Zen Pro addresses this issue head-on.

Sound Quality​

The general sound signature of the Dunu Zen Pro can be termed as neutral.



I could not hear any evident coloration across the frequency spectrum at all, and they are one of the few neutrally-tuned, single-dynamic driver IEMs in the TOTL space. There is one caveat though: the sound signature can change noticeably based upon the tip selection and insertion depth. I recommend trying a few of the supplied eartips and finding out the one that works best.

The Zen Pro goes for a controlled sub-bass boost of about 5dB with the sub-bass being strongest around 50Hz. Bass rises slowly from 400Hz, which helps the mid-bass gain some body and weight. The mid-bass is really well tuned to my ears, with no bass bleed into the lower-mids.

Snare hits are dense without being overbearing. The bass is very agile for a dynamic driver and can keep up with fast basslines in many metal songs, e.g. All that Remains’ This Calling. Bass texture stands out the most, with different instruments displaying their characteristic sound in busy mixes.

Where the bass falters is the rumble factor. Sub-bass is present but won’t suit your bass-head desires. Dunu went for a neutral tuning so a dense sub-bass would compromise mid-bass texture to some degree. Another intangible that is missing is the sense of slam.

Midrange is where Dunu brought about some noticeable changes from the OG Zen. The OG Zen have a pronounced upper-mid, further exaggerated by a peak around 4KHz. The 4KHz peak is noticeably dialed down here and the transition from lower-mids to upper-mids follows a near-reference tuning.

Male vocals and low guitar notes have exemplary clarity and precision. The only bit of coloration in the midrange is in the hint of warmth stemming from the upper-bass rise around 300Hz. This adds body to baritone vocals and makes them more true-to-life.

The upper-mids are well controlled and avoid shoutiness and shrillness. Both male and female vocals have excellent articulation and string instruments have lifelike attack-decay. You can pick out the different tone color of nylon and steel string guitars and distortion guitars never sound too forward. The Zen Pro’s midrange tuning facilitates long-term listening and justifies the “Zen” nomenclature.

The biggest tuning change from the OG Zen happens in the treble region. The OG version have a steep treble roll-off from 10KHz which counter-balances the lack of brilliance with a deliberate peak around 8KHz. This does not induce sibilance but will alter the timbre of cymbal hits and their natural decay is abrupt and lacks extension.

Zen Pro rectifies this issue to a degree. The 8KHz peak is toned down somewhat and there are additional peaks in the upper-treble region (near 11.5KHz and 14.5KHz to my ears).

There are a couple shortcomings in the treble though. Firstly: the 6KHz dip could be less prominent. This can be perceived as a lack of “clarity” in the treble region by many listeners. However, it is fairly simple to equalize that part based on individual taste and treble tolerance.

The other shortcoming is the peak around 11.5KHz which to my ears can be a bit intense in certain recordings and highlights the shimmer of the instruments more than necessary.

Overall soundstage is a definite improvement over the original Zen but falls short of some of their peers. The focus on the midrange pulls the vocals closer to the listener and this can reduce the perception of stage width. Stage depth and height were fairly good given the in-ear form-factor.

Imaging is very good, with certain shortfalls that plague every IEM out there, e.g. things that are happening at the back of your head are not positioned correctly. The rest of the instruments are well placed and positional cues are readily picked up.

Microdynamics are class-leading, beating the venerable OG Zen which lead the metric in this price bracket. In high dynamic-range recordings every subtlety is picked up. Dave Brubeck’s Take Five has small gradations in cymbal volume which one can easily recognize when listening to the Zen Pro.

Disappointingly, macrodynamic punch is lacking vs the OG Zen. The driver speed is even faster than the original, however, and can keep up with the busiest of tracks while keeping the outline of individual instruments intact.

General timbre is natural albeit the upper-treble peaks can at times sound “zingy”. Overall resolution is excellent for a single-dynamic driver, falling short of the technical performance of some pure Beryllium foil drivers. Finally, layering is immaculate with backing vocals being delightfully drawn out from the mix.

Bass: 4.5/5
Mids: 5/5
Treble: 4/5
Imaging/Separation: 4/5
Staging: 4/5
Dynamics/Speed: 4/5

Comparisons​

Vs Dunu Zen​

Build quality, accessories, comfort, and isolation are largely similar between these models with the stock cable being the only difference. I much prefer the CHORD cable on the Zen Pro over the bulky DUW-03. Otherwise, they are similar in everything but the sound.

OG Zen goes for a more energetic and raw tuning. The lack of treble extension is evident, but the focus on mid-treble keeps the highs from going dark. Bass has more slam and physicality on the original with superior macrodynamics. Stage is narrower with more up-front vocals. Guitar riffs are treated as first-class citizens and the OG Zen were rather unique in their delivery of Rock and Metal tracks.

The Zen Pro dials the bass and mids down a notch and things calm down noticeably. With better upper-treble extension and less mid-treble focus the treble also feels toned down. The Zen Pro excels in singer/songwriter tracks and classical music as a result. The stage is wider, deeper, with better layering.

Instrument separation is largely similar on both, and so is the imaging, but overall resolution is higher on the Zen Pro. For the USD $200 premium, you get a number of noticeable improvements indeed. I did feel let down by the reduced bass slam as that was one of the highlights for me on the OG Zen, so I would suggest OG Zen users to audition the Zen Pro if possible before purchase.

Vs Unique Melody MEST​

UM MEST (version 1) is now discontinued but it is a model I have on hand while making comparisons. In terms of build, comfort, design, and accessories the Zen Pro wins without contest. Isolation is better on the MEST but you compromise on comfort.



As for sound, the MEST are unabashedly colored with emphasis in both the bass and treble frequencies. The actual bass quality is far higher on the Zen Pro though, with superior bass texture and speed. The bass driver on the MEST is noticeably slow and compromises the coherency of the IEMs.

Midrange is thicker and more recessed on the MEST. Treble, on the other hand, goes for added focus near the presence region with a 6KHz peak and only starts to roll-off around 15KHz. This results in a brilliant treble rendition with gobs of air and added intensity. I personally do not like this hyper-active treble response and always EQ’ed the treble down to suit my own tastes.

Soundstage and imaging are far superior on the MEST, rivaling many full-size cans. Separation is also better, although layering, especially in the midrange, is better on the Zen Pro. Overall resolution is higher on the MEST.

The UM MEST is a technical marvel with the bone-conduction driver and the quad-brid setup overpowers the single-dynamic Zen Pro when it comes to raw resolution. For me, resolution is not everything and the Zen Pro’s smoother, calmer presentation makes me prefer them over the MEST for long-listening sessions. For short listens and absolute resolving prowess, the original MEST is still one of the best around.

Conclusion​

The Dunu Zen Pro have excellent build, comfort, and a stellar accessory pack. Dunu fixed some of the issues found on the original release and it is always great to see brands listening to community feedback.

I do feel that some of the magic of the OG Zen has been lost. I miss the bass slam of the original and in certain tracks I wish there were a bit more energy in the presentation. On the other hand, the Zen Pro won’t beat the tribrids and quad-brids in the market that are targeting absolute resolution.

Nevertheless, the tuning is really well done overall and has a certain calmness to it which is often abandoned in the TOTL space to showcase better technicalities.

Disclaimers and Caveats

First of all, I would like to thank @DUNU-Topsound for the opportunity to share further impressions of my experience with the ZEN PRO - following the ZEN PRO tour in November, DUNU kindly provided me with a discount to purchase a unit for myself. It is always a pleasure to engage with the DUNU reps, their wealth of knowledge and customer focus is admirable.

I am by no means a professional reviewer but enjoy sharing my impressions as part of the hobby. My views expressed here are entirely my own, based on just over a month's experience with the ZEN PRO.

It should probably go without saying but I will note none-the-less: this is an incredibly subjective hobby and we all hear things differently in terms of what actually equates to listening pleasure. With that said, it should be reasonable to map out findings that provide context for others to take a position on whether the item might meet their preferences. My review won't be deeply technical, as I'm not deeply technical - I am however a technology and music fanatic so will attempt to best convey my impressions. Please feel free to ask questions in the comments and I will do my best to respond with a meaningful response...

Alert! YMMV (your mileage may vary) - this is what I have heard with my music preferences relative to other IEMs in my collection.

To burn-in or not burn-in: a hot topic, pardon the pun but it does indeed divide. In my experience, brain or technology, I have perceived changes over time and ensure that I allow time to burn-in, while listening at various intervals. I allowed about about 3-4 days of burn-in on arrival and have clocked up many more hours since.

Preamble

I owned the original DUNU ZEN which I purchased upon launch in January 2020. It was my first 'expensive' IEM and a wonderful introduction to a more premium experience. It was also my first DUNU and the unboxing plus selection of accessories left a lasting impression, thankfully replicated with ZEN PRO as it is the exact same, bar a different colour sleeve on the box.

Since then, I've explored quite a few IEMs and driver configs, landing on single DDs as my preferred choice for the most part - I've been intrigued as to how different brands are tuned, and how they lend themselves to various genres. I was on a bit of a mssion to determine what the 'best' single DD, but I've given up on that now - I've satisfied myself with the fact that they have differing attributes that work well with some genres better than others and for that reason, I've ended up with a few 'go-to' single DDs, depending on what I'm listening to. That said, ZEN PRO is the most competent all-rounder I've heard, more on that later.



DUNU

DUNU will be known to most, if not all Head-Fi regulars, but worth giving a bit of background information for newcomers to the site or indeed the hobby. I won't attempt to write a bio on their behalf, rather just quote the first paragraph from their website:

DUNU innovates for music lovers. Our mission has been to be at the cutting edge of audio, creating premium, high-resolution audio products for the world's most demanding audio enthusiasts. With roots as an ODM/OEM establishment that produced products for the largest and most prominent audio & telecommunications companies around, DUNU has dedicated itself to the development and manufacture of earphone products since 1994.
https://www.dunu-topsound.com/about

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ZEN PRO Specifications (from DUNU website)

• FREQUENCY RESPONSE: 5 Hz – 40 kHz
• SENSITIVITY: 112 ± 1 dB at 1 kHz
• IMPEDANCE: 16 Ω at 1 kHz
• TOTAL HARMONIC DISTORTION: < 0.2% at 1 kHz

DRIVE MODULE

DIAPHRAGM: Second Generation Magnesium-Aluminum Alloy Dome with Nanoporous Amorphous Carbon Coating (nanoDLC) and Fully Independent Suspension Surround
MAGNET ASSEMBLY: > 1.8 T External Ring-Type Neodymium Magnet

HOUSING

MATERIAL: S316 Stainless Steel
INTEGRATION(S): Patented Air Control Impedance System (ACIS)

DUNU ZEN PRO is available from a number of online stores at a retail price of $899. I purchased mine directly from DUNU, and it is available HERE

Unboxing & Accessories

The DUNU unboxing is quite an experience and one of the best I've had with any IEM. There is fantastic attention to detail, and a real sense of having purchased a premium product. I know this is not important to everyone but I'm a sucker for a good unboxing and it's something I really look forward to when a new IEM arrives. Of course its the product that matters most, but I like the start of the journey to be one to remember. With that said, I will keep it brief and let the pictures tell the story...











An excellent selection of accessories, to include:

• An assortment of tips to meet all requirements
• Shell protection sleeve
• Airplane adaptor
• Cleaning cloth
• Brush cleaner
• Shirt clip
• Case

Fit, cable, and Isolation

The shells fit very well in my ears, and I can use for extended periods with limited fatigue, though they do get tired beyond about 2 hours - better than most IEMs for me. Isolation is reasonably good, I've used out walking and while they certainly don't block out sound, I get a good balance of hearing music and local traffic - I prefer not to block out all sounds when walking, and these work well.

The cable when in use, has low microphonics, and is light around my ears. It tangles easily though, I often find myself trying to straighten it out when I take it out of the case. This is a bit annoying and a minor niggle really, but worth noting.

Evaluation Setup: Sources, Tips, and Music...

The bulk of my listening has been with the Cayin N6ii-Ti, using both the R01 and E02 modules. Some listening also with the Sony NW-WM1A, L&P W2, Sony ZX507, and iFi Gryphon. I've been using the AET07 for the majority of the time, some experimentation with others but typically revert back to the AET07 as they are my top choice now for most IEMs.



I listen to a wide variety of genres, from ambient to indie rock, and lots in between. I must note that I have a preference for electronic music in some form with IEMs - ambient, IDM, techno, house to name a few. Important to point that out as clearly how an IEM presents electronic music will differ from non-electronic instruments - I'd argue its easier to do electronic on IEMs than a lot of other genres, somewhat less emphasis on timbre for example, or indeed how accurate vocals sound. That said, there are still dramatic differences in how electronic music can sound from one IEM to another, especially more complex tracks where speed and detail retrieval is put to the test.

While I've obviously listened to a lot of music over the last month, I've selected a few tracks that represent a mix of my library - I feel this helps to understand how we may or may not connect in terms of music preferences. This is a good selection to really test an IEM too.

Test Tracks


Sound Impressions

ZEN PRO to my ears, is a somewhat W-shaped IEM with wonderfully balanced, warm-ish leaning tuning - I don't hear a specific emphasis in low, mid, or highs, they seem to sit pretty much level. While not a 'bass head' IEM, it can certainly can pack a punch when needed and I personally never feel at a loss in this regard, even if other single DDs are more capable - more on that later. Mids are lush and all encompasing, allowing great flexibilty with a huge variety of genres. Treble is precise and sufficient to ensure instruments/vocals in the higher registers are well represented without sibilance or any sense of harshness. I feel the term 'jack of all trades' is somewhat derogatory and I'm reluctant using the term, but it is applicable in that ZEN PRO can play any genre I've tested, and do at worst a good, but mostly an excellent job - nothing seems to phase it, and I have tested it extensively with several challenging tracks.

There is a reasonably wide but not particularly tall and realistic soundstage. It strikes a superb balance from a technical / musicality standpoint - I enjoy how I can pick out micro details, and hear various instruments sitting clearly and well separated on the stage, but I can still sink in to the overall musical experience, not getting too sucked in to the detail if I choose not to - this to me, requires masterful tuning and not typically something that can be achieved at lower price points - you do get what you pay for...

In terms of speed, ZEN PRO can handle the fastest and most complex tracks. Many of my test tracks incorporate complex drum programming, coupled with numerous synths, samples and vocals all competing for space on stage - ZEN PRO handles with aplomb, never faultering. Incredibly impressive to hear the peak in a track like 'Skywalker' in the list above, numerous components climaxing, leading to a potentially challenging outcome on an inferiour driver, but instead sounding sublime on ZEN PRO.

For slower, vocals focused tracks that lean less electronic, and more instrumental - ZEN PRO renders both male and female vocals with ease, fantastic timbre and often intimate delivery. The stunning 'Body' by Julia Jacklin is utterly beautiful, her voice up front and centre, supported with a gentle strumming guitar, slow percussion, and gentle bassline.

Relaxed instrumental, modern/neo classical or ambient are all beautifully engaging. I was testing the above 'Travelled Road' by Yagya, and ended up repeating it four times it was that stunning. Shivers... and almost tears, the amazing power of music and how it connects to emotions.

I've read comments to suggest the timbre leans metallic - I don't experience this but I can say that I have other IEMs that have better timbre in some very specific scenarios - FAudio Dark Sky for example has for my ears (in my collection), unbeatable timbre when it comes to jazz in particular - double bass, sax, and percussion sounds utterly spectacular and lifelike. ZEN PRO does an excellent job, but the improvement is there when I A/B vs Dark Sky.

Overall, I look for a listening experience in IEMs that allow me to fully immerse myself in the experience, providing a good blend of technicalities and musical enagement - this is my top criteria, and how I most enjoy music. ZEN PRO is the definition of this criteria for me, coupled with an ability to play any music I throw at it - the only other IEM in my collection that I can say the same for is the Oriolus Traillii, over 5x the cost...

Comparisons

FAudio Dark Sky ($1,150)

First up is the FAudio Dark Sky and I've cut a corner here by lifting the comparison I did with ZEN PRO in my review of Dark Sky, still applicable and edited for the context of this review...

As noted ZEN PRO performs very well with every genre, but not with the same level of finesse that Dark Sky manages in areas of speciality such as jazz and others that have a clear focus on excellent timbre rendition of instruments and vocals. The stage width on ZEN PRO is smaller, and doesn’t reach the same heights as Dark Sky. Bass doesn’t dig as deep but honestly, once my ears have tuned back to ZEN PRO, I don’t feel at a loss. Likewise there is more upper-end energy available from Dark Sky, a somewhat cooler hue in comparison which is what I believe injects more analytical capability - ZEN PRO has more foward mids also, adding enhanced emotion and musicality to the mix.



Sennheiser IE900 ($1,299)

The IE900 is still one of my favourite IEMs, it absolutely blew me away when I first got my hands on it back in May 2021 - and briefly cured me of upgraditis for about 3 months, the longest I've had in this hobby without an itch forming. It has some of the most incredible bass I've heard in any IEM, and still the one to beat in terms of depth, slam/punch, speed and lifelike rendition - often reminding me of the good old days of clubbing, the pounding bass hitting you on the dancefloor. Quite a feat for such small drivers. Likewise the treble is a thing of beauty, sitting on the cusp of too much, but that actually becomes a real sweet spot. More V-shaped and in that context, I feel like I'm listening to set of high quality bookshelf speakers, slap bang in the middle. The somewhat recessed mids on IE900 mean I'm less inclined to listen to ambient, vocals, or more instrumental leaning music - ZEN PRO fills this gap perfectly - though I must say, IE900 can do a good job there, just not as capable as ZEN PRO to my ears.



Oriolus Isabellae ($499)

Excellent IEM, and I consider more specialist in my collecton - hard to beat for female vocals, acoustic, modern classical and ambient. Often my choice for listening in bed before sleep. Smaller stage versus ZEN PRO, far less capable when it comes to faster electronic genres, and lacks the kick in the mid-bass to satisfy my bass requirements in genres such as techno, IDM, house, etc. But I would probably lean towards Isa from a timbre perspective in the previously mentioned genres. Like Dark Sky, I feel it is somewhat more specialist compared to ZEN PRO.



FiiO FH9 ($599)

This comparison should actually be the FD7, a single DD that is highly regarded by many, and on my radar a number of months. I ordered it a week or so ago, and when it arrived, I opened the packaging with great excitement, only to find they had sent the FH9 - a 6 BA / 1 DD hybrid. Disappointed, but curious and also impatient to start dealing with the returns process, I went ahead and opened it. I'll keep it brief, as I've only had it a week and don't feel qualified to fully compare but I will say FH9 has been a very pleasant surprise, an incredibly capable IEM with a tuning that leans more fun versus ZEN PRO and with a spectacular stage, with excellent coherency for a hybrid. More powerful bass versus ZEN PRO, digs very deep and excellent, fast mid bass - not quite as pristine as IE900, but not 'wooly' either. The BA treble reaches higher than ZEN PRO, and in some cases, can touch harsh, especially with lower quality recordings - ZEN PRO is more forgiving in this regard. The stage, layering, and imaging on FH9 is incredibly impressive, and beats ZEN PRO hands down for sheer size - ZEN PRO sounds more intimate when I switch, with a more pristine tuning - balanced and polite, versus exciting, big, and dramatic. FH9 has been an unexpected surprise for me, and likely the subject of my next review. They complement each other very well.



Conclusion

It probably doesn't come as a surprise for me to conclude by declaring my love for the ZEN PRO. Aside from Traillii, it is the best all-rounder IEM I've heard on my journey - capable of playing absolutely any genre, with a wonderful mix of technical prowess, blended with an incredibly captivating, emotive, and engaging listening experience. It is an IEM I reach for probably the most often, rarely a day goes by without checking in. I wrestled with whether I should rate as 4.5 or 5, but when I sat looking at the screen for several minutes, trying to think of faults that justify only 4.5, that quickly answered my question.

Congratulations to DUNU for bringing such a wonderful product to the market, a tough act to follow and I look forward to seeing what they have up their sleeve next.

Preamble: My Zen Pro was purchsed by me from Amazon. There was an open box discount but I was not asked or required to review it. This review is motivated by nothing other than my wanting to express and share my regard for this IEM.

Today I am reviewing the Zen Pro, a single DD IEM from Dunu. Dunu is one of those companies I’ve long been aware of through positive impressions I’ve heard from friends of IEMs like the Luna, SA6 and earlier models like the DK3001. However given that I live in Canada-- comparatively an IEM wasteland relative to many other parts of the world— I am completely at the mercy of whatever IEMs I can borrow through friends or hear through the rare tour I have access to. As it happens the Zen Pro is the first Dunu IEM I’ve had the pleasure to hear.

As is my custom whenever I do a review like this I begin with a preamble describing a bit about myself, my preferences and where I’m at on my own audio journey as, in addition to the satisfaction I derive from expressing myself in words, this gives potential readers a bit of background and context that will hopefully give a greater sense of where I’m coming from with respect to whatever IEM currently owns my heart—in this case the Dunu Zen Pro.

I have found over time that the scope of what I like or don't like can't be captured by a single target curve or tuning ideal-- my tastes, while definitely possessing some trends (a tendency towards DDs, for example), have evaded all my attempts to reduce them to a rule or small set of rules. I will say two things however—firstly that of all the main bands of the FR it’s the mid-range that I’ve started to recognize as the one I’m most fussy about. To wit: lately it seems to me that it doesn’t matter how good the bass, treble, technicalities and so forth are if the midrange isn’t to my liking none of it will matter.

Secondly, certain things—like perception of micro-detail—that often get elevated to the highest ranks of importance by the audiophile orthodoxy, has never been a massive priority for me personally. Accordingly I often don't rank IEMs noted primarily for their technical chops as highly as many others do. For me the most important thing, to put it bluntly and at the risk of inciting a few facepalms, is how the IEM in question makes me feel when I listen to it. I have a degree in mathematics & philosophy and teach the former for a living. I run a chess club and study great chess matches with intense interest and passion-- most of my life is focused on logical structures, rules, sequences, arguments and symmetries...and yet when it comes to music and this hobby it is 100% about feeling for me. When I'm listening to a great piece of music-- be it Barry, Coltrane, McCartney or Beethoven-- I am not reasoning or thinking or questioning or analyzing about who or what or how long-- I am having an experience, fundamentally, of the heart.

On that note let’s talk about the Dunu Zen Pro.


TLDR: Neutral & highly transparent sound with a hint of warmth. Blissfully coherent. Natural, bodied, balanced, dynamic, energetic & holographic sound. Impeccably technical & detailed, super linear, non-fatiguing though can be a bit vibrant in the upper mids depending on source. Beautiful timbre—to my ears especially with electric guitars, and horns. They're probably just on the "emotive over technical" side of the spectrum. Imaging & layering is top tier...staging is not massive but very layered & deep and everything is very well placed. Mids are even-keeled & clear, bass sometimes felt more than heard…but always felt, very well extended and reaches from the stygian depths. Treble is non-fatiguing, clear & decently extended. All in all the balance across the spectrum is wonderful. I don’t want to sound like a shill but holy balls do I love these IEMs. Listening to them through the AK SR25ii or Cayin RU6 and my heart is in want of nothing.

Fundamentals

I’m not going to dwell too much on packaging & technical specs as it’s not really my style and that info is available readily elsewhere. I will say though that the Zen Pro come equipped with the most powerful set of magnets I’ve ever seen on a pair of IEMs. The magnets are so powerful in fact that if they get too close the Zen Pro earpieces will lunge and cling together. II’m careful to not let them do this though as even micro-impacts can damage the small drivers in these IEMs. I’m curious about the effects of the magnets however. I know that magnets are often a feature of dynamic drivers—growing up my buddy’s dad had a set of speakers with magnets so powerful they wrecked 2-3 of his TVs. Certainly they contribute to the sonic profile somewhere via the magnetic field they generate but I’m not sure how. The Zen Pro is notable for a very muscular & ballsy sound across the whole spectrum. The sound exudes weight, texture & authority—but not in an intrusive or belligerent way…rather in a seductive, well balanced and disciplined way. This muscular character is one of those intangible factors I’ve long been drawn to in IEMs without really zoning in on it as a particular point of interest. The only other IEM that has this quality to the same extent is the Dorado 2020—and indeed this is, I am finding, one of the main quality that has endeared me to this IEM. In the case of the Dorado 2020 I believe the hardness of the ceramic shell is what gives the sound it signature solidity and clarity—is the powerful magnet in the Zen Pro a different pathway to the same sonic character? This is something I will be looking into going forward.

Drawn together:


My understanding is that the original Zen was similar to the Zen Pro in many ways and has been refined due to some feedback they received on that earlier model. I had always heard of Dunu IEMs being notable for their bass and the OG Zen is probably the close I’d come prior to the Zen Pro to purchasing a Dunu IEM. What held me back at the time were consistent reports I’d heard of the OG Zen having too much energy in the upper mids—a consistent deal breaker for me. My decision to purchase the Zen Pro—in spite of the fact that I really didn’t need another IEM at the time—was based on a perfect storm of events consisting of some glowing reports I’d heard from fellow enthusiasts, the perpetual curiosity that afflicts all of us who regularly chase IEMs, my love of single DDs and long-held curiosity about Dunu. Couple all of that with the wind-in-one's-sails & opportunism that often attends finding a good deal at Amazon…and well the rest is history. I'm happy to say that my leap-of-faith towards the Dunu Zen Pro has turned into what is currently shaping up to be the definitive highlight in a year full of highlights for me in this hobby.

So how do they sound?

The Zen Pro put forward an impeccably balanced & exceedingly technical, bodied, dynamic, clear, detailed & spacious sound-- and the timbre is excellent across the board. Sound is forward and energetic-- these are not really what I'd call a relaxed listen per se. Guitars, horns, percussion, cymbals all sound perfectly natural to me. Guitars have both body & bite in nice measure. To be perfectly honest I never fully understood the appeal of neutral tuning until I heard these-- they are just so fun, engaging & satisfying to listen to and yet effortlessly technical, transparent and precise in their presentation. Everything feels so open with each element feeling, no matter how miniscule, is given its own clearly defined piece of the sonic tapestry in which to shine. I often classify IEMs as veering more towards an analytic (technical, detailed, precise) sound vs. a more fun & emotional sound. The Zen Pro strike as perfect a balance between those two qualities as any I have heard-- there is no excess and everything is represented perfectly and their ballsy dynamic sound is a constant pleasure. It was only after my initial musings of the Zen Pro that it occurred to me that the name "Zen" is perfectly apt for these IEMs. The Zen Pro is a little source sensitive and on more v-shaped or brighter players the upper mid/lower treble region can display a touch of harshness at times-- but for me it was minimal and this has been totally mitigated for me since using the Astell & Kern SR25ii and Cayin RU6 dongle. Synergy is a thing however it bears noting that this appears not to be an IEM you can plug into whatever source and get the same result...so YMMV there.


Bass, Mids & Treble

The Zen Pro are some the most balanced IEMs I’ve ever heard. If you’re looking for a bass or treble specialist they may not be the best bet—the Sennheiser IE900 might be something to look at there. Alternately if you want something with more of a pure focus on the mids then the Oriolus Isabellae may be work checking out. Where the Zen Pro knocks it out of the park is how it manages to bring out the best and be totally satisfying across the entire FR spectrum. When listening to the Zen Pro I feel like am maximizing my enjoyment of the entirety of what I’m listening to to a greater extent than I’ve yet experienced with an IEM. As mentioned some have reported a touch of metallic timbre and harshness up top but in my experience if you get the right source this ceases to be an issue.

I am particularly impressed with the bass on the Zen Pro. It doesn't jump out at you at first-- and you might initially be tempted to think of the Zen Pro as bass-lite...which it isn't at all. It's super tactile & well defined-- and the extension is deceptively good. When the bass hits it seems to reach up from the murkiest depths-- it's a bit like the Odin this way and I would describe the bass on them both as reserved yet highly efficient, precise & powerful. Zen Pro’s bass is the sonic equivalent of Bruce Lee’s one inch punch. Sub & mid bass are, along with everything else, nicely balanced. A lot has been made about Zen Pro’s sub-bass roll off…but to me the graph is deceptive. Zen Pro’s bass has balls & weight—even when you don’t quite hear it there’s never any doubt it’s there.

Zen Pro’s bass reminds me of the bass on the Solaris...almost homeopathic in amount but the authority, weight & texture is spot on and it's subdued enough to maintain a sense of balance across the FR. I have many bass-leaning IEMs and it’s nice have one that's close to neutral...and a highly technical single DD to boot-- it's a big win for me. I think the ticket to the bass working for me is that it's got a nice sub -> mid-bass transition...the bass doesn't overwhelm but simultaneously it's warm and bodied enough that I don't feel anything is lacking. The bass on the Zen Pro is also much more technical and satisfying to my ears than the bass on the Solaris was. You’re not going to walk away after your first listen to the Zen Pro and go “wow! That bass!” like you will with something like the IE900 but after 3 weeks with these IEMs my awe of and appreciation for the bass on the Zen Pro increases daily.



The midrange is another highlight of the Zen Pro. It’s not as perfectly romantic, intimate and seductive as the midrange on the Isabellae is…but it is forward, clear, unveiled, layered, detailed and possessing of a wonderful natural timbre. In terms of vocals Mark Knopfler, Howlin’ Wolf, Morrissey, Fogerty, Sinatra, Sky Edwards all sound wonderful to me—bodied, full and clear. I’m not a particular expert on female vocals so I’ll defer discussing them…but I haven’t heard any issues. Instruments all sound full, dynamic, natural, detailed & clear. Of particular note to me are electric guitars (Knopfler’s strat has seldom sounded as good to me) but also saxophones—strings and horns in general.

Highs are (for me) adequately extended, clear and non-fatiguing. Highs historically have been the hardest things for single DDs to get right for me—often coming across as metallic, harsh or lacking in extension. Most of my favorite highs in IEMs come from IEMs with e-stat highs (like the Bravado 2 or Elysium) or with another type of DD (as in the IER Z1R). The highs of the Zen Pro don’t fall into the usual pitfalls for me, but they also don’t quite soar to the same heights (pun intended) as the highs on something like the IE900 do. What you get instead is a more even-keeled presentation across the spectrum.

Technical Chops

As I’ve come to understand the term “technicalities” are those features of an IEMs sound that allow it to create in the mind of the listener a fully vivid & realized head stage. Stage on the Zen Pro is not massive per se but is fathomlessly deep, layered and detailed. Imaging is superb with voals ever at the front and centre.. The Zen Pro is technical enough to satisfy those who usually pursue BA driven sets and the timbre is natural, thick and engaging enough for those of us who usually gravitate towards DDs. I was considering the word holographic with respect to these IEMs and in particular around what the word actually means. One of the characteristic features of a holographic image is that the entirety of the image is present even in tiniest part of it—in this sense while the stage certainly isn’t as massive as on something like the Campfire Solaris I do very much get that holographic feel from the coherent soundscape they present in that it doesn’t matter where I place my attention the entirety of the sonic spectrum is always to the fore—it’s a rather impressive experience and one I feel that to this point has not been fully captured on any hybrid setup.

As a rule the IEMs I gravitate towards aren't defined by their technical chops and I often wind up explaining myself in terms like "well I prefer timbre over technicalities anyway". The Zen Pro is remarkable in its ability to provide both bodied, natural DD timbre as well as, not just technicalities that "get the job done" but thoroughly impressive technicalities. I had no idea a single DD in IEMs could image & stage like this-- it's so deep and vividly and precise. Vocals are un-veiled, sibilance free and naturally seductive-- and the FR is smooth from top to bottom. While there is some sensitivity to sources with respect to some harshness up top and metallic timbre—on the right source like the Cayin RU6 or AKSR35ii— there is no fatigue, no peaks or pressure points to my ears though it must be stated that I do love a mice punchy, dynamic in-your-face sound as you get with many Campfire IEMs so YMMV there. For my own tastes I've never heard a single DD this consistently good across the FR.



Single DDs have the capacity to afford an amazing coherence—and the Zen Pro takes full advantage. The whole soundscape manifests as one cohesive, unified and entire structure of sound that, when coupled with natural bodied DD timbre, allows for us to be immersed in a sonic palace of natural grandeur and engagement that capture's both one's heart and attention in a way that hasn't yet been fully replicated in hybrid or non-DD setups-- at least to my ears. Traillii may be the only exception to this I've heard but I haven't yet spent unbroken days with one so ultimately the jury's still out on that one for me.

I think the outstanding feature of the Zen Pro from a technical standpoint is its resolution. I used to have a hard time talking about resolution because I wasn’t really sure what it meant and always thought of it as being synonymous with detail. In J Gordon Holt’s audio glossary he defines resolution as “that quality of sound reproduction which enables the listener to distinguish between, and follow the melodic lines of, the individual voices or instruments comprising a large performing group”—in other words resolution is in actuality a combination of things like detail and what I typically think of as “instrument separation”. Based on this definition I can assuredly say that the resolution of the Zen Pro is off the charts good and easily the best I’ve ever heard from a single DD. Through the Zen Pro every layer, every instrument, every performer manifests simultaneously with their own individual air, space and identity and also as an intrinsic part of a unified sonic tapestry. The more I listen to the Zen Pro the more I settle in to its fully realized, detailed, living, vibrant soundscape.



Comparisons

VS. Oriolus Isabellae

Compared to the Zen Pro Isabellae feels like more of a specialist-- more intimate, mid-range/instrument/vocal focused. Zen Pro by comparison is balanced across the board and it wouldn't surprise me if, once the dust settled, I proclaim it the best "all-rounder" I've yet heard. It doesn't quite sweep me off my feet and draw me into the mid-range like Isa does, and to be fair it's midrange on the whole probably isn't as emotionally evocative-- but the bass, treble and overall tonal balance & technical chops of Zen Pro is a decided step up from Isa imho.

I want to caveat the above statement-- one area where Zen Pro does shine above Isa is in the treble-- it has better extension and sparkle up top. Bass is about equal in quality, but tuned differently. It's not really fair to say that Zen Pro has a better tonal balance because I think that the goals were different with each IEM. Isa was never meant to be balanced across the FR-- it's about warmth and intimacy in the mid-range and it pulls this off marvelously. Zen Pro is more about balance and technicalities and it also pulls this off to great effect. On the whole each succeeds in its own area and I don't think it's really fair to say one is better than the other as they're like two fine but distinct wines. Zen Pro isolates better and is probably a better choice for a versatile all rounder. It doesn't romance me like Isa does, however.

Vs. Fiio FD7

From memory Zen Pro has a better tonal balance than the FD7 for me. I know some have described FD7 as "warm and bassy" but for me it was not that at all-- it achieved a tremendous amount of resolution up top but it achieved that by selling the low end short to my ears. Zen Pro does not have this problem-- it is very balanced and while there's certainly not a bass/lower mid emphasis or anything there is certainly nothing lacking there to my ears. The only ding in Zen Pro's armour for me so far is that it appears to be a little source sensitive-- the upper mids as has been mentioned straddle the line of being a bit too energetic at times…but with the right source and some time this seems to go away completely.



VS 7HZ Timeless

Timeless puts forward a presentation that is almost as balanced, more resolving, possibly better micro & macro dynamics. Timeless is an IEM that takes you by surprise with its naturalness whereas the Zen Pro is more in-your-face about it. In terms of engagement they’re probably about equal for me but Zen Pro is more energetic and in your face with that more bodied & ballsy sound…particularly down low…that other drivers just can’t emulate. Timeless is more effortless and natural…particularly through something like the Cayin RU6. Timeless is a shining star among releases this year but still has a couple kinks to work out—on its own terms little can touch it but it doesn’t quite lure me way for long from my favorite DDs like the Zen Pro. With the technology involved and the pace of innovation these days that day may not be too far behind.

VS Sennheiser IE900

My time the IE900 was very brief but it differs from Zen Pro in that, where Zen Pro is balanced & neutral the IE900 has a decided bass & treble specialty with the mids pushed back. IE900 has a tremendous reputation and in its own way it excels. If you want top tier bass & treble it’s by far the better choice—however if you’re looking for balance & neutrality in an all rounder the Zen Pro is worth a look.

VS Moondrop Kato

These are quite similar to the Zen Pro-- less balance, more tilted towards the bass, a lot less technical, more of a generic tuning. Not factoring in cost the Zen Pro eats them alive however when you consider that they only cost $200 or less than 25% of the Zen Pro they come off as a benchmark for the price tier they occupy. If you want an even keeled IEM that sounds good with everything, has no glaring flaws in bass, mids or treble, has more than adequate technical chops and you don't want to spend more than $300 then these are an easy rec. They're great for what they are but don't have any real standout qualities-- they don't have the balance of emotive engagement, impeccable tonal balance & technical prowess of the Zen Pro, or the divine mids and capacity for genuine intimacy of the Isabellae. They're a standout for $300 but they would not come close to tempting me away from the Zen Pro.


Wrapup

One of the most profound lessons I’ve learned in this hobby recently can be summed up in a quote by Steve Jobs—that I think I even featured in an earlier review in the year: “Sometimes you don’t know what you want until someone shows you”…how true this is. For myself I have found that whenever I try to really pigeon-hole my own preferences—which I thought I was on the verge of doing once I started really comparing the graphs of many of my favorite IEMs like the Duo, Dorado and Isabellae—along will come an IEM like the Zen Pro that throws all of that to the wind and completely reorients my own idea of what I’m looking for.

This brings me to another lesson—one so important that I’ve probably restated it in one form or another every time I’ve sat down to review an IEM: never judge an IEM by its graph. On two occasions this year—first with the Isabellae and later with the Zen Pro—had I gone just by the graph I would have never considered either IEM however upon listening to both I was instantly swept off my feet and smitten, albeit for different reasons. The point: ever be ready to try something new and always be willing to let your own ears be the final judge.

In closing I really want to emphasize the importance in recognizing the different approaches everyone may take in this hobby as they wend their way along the pathway to audio Zen (pun, again, intended). As hinted at earlier I often comment that there are two main ways to approach the listening experience with an IEM-- either intellectually or emotionally. The former implies looking at the different components of the sound through a proverbial microscope and the latter implies being more concerned with how one responds emotionally to the cohesive whole of the experience. Both approaches are valid however I think most people are skewed more to one side or the other. I like having a balance of different perspectives out there and so long as they're sincere they can all be helpful. As I said above my own personal bias is strongly towards the "emotional' side. When forming & writing impressions my inclination is much more towards the overall picture of the emotional experience of listening to an IEM-- and consequently when looking for impressions of others the number one thing I look for is someone having the same sort of emotional reaction to an IEM that I myself am craving...though I know some find this approach too wishy washy and not very helpful in much the same way that some find an overly analytical approach to be too devoid of the necessary romance of the experience. The beauty of this hobby and communities like this one is we have access to the full spectrum of different opinions and approaches and are free to take or leave what works for us or what doesn't.

Caleb Roseneau of Campfire audio in an interview I heard once described the main differences in BA vs. DD drivers being that BAs are better at "describing" sound and DDs are better at making you feel it. In light of the distinction I just made above DDs are more naturally suited to emotional engagement (evoking feeling) and BAs are more suited to intellectual engagement (being more detailed and technically precise). There is of course overlap but so far in my experience the best BA IEMs can't compete with the best DD IEMs in terms of sounding natural and evoking a certain type of emotional engagement and conversely the best DD IEMs can't compete with the best BA IEMs when it comes to technical skill and precision.

With the Dunu Zen Pro we have in my estimation a benchmark in the IEM world. It is a single DD that manages to take an extraordinarily balanced tuning and simultaneously imbue it with the bodied natural timbre one finds in a DD and a degree of technical perfection that, while certainly falling short of the most purely technical sets using BAs or e-stats—nonetheless leaves little to be desired. Dunu strikes me as one of those brands that have been quietly plying their trade for years...often below the radar. I never heard the OG Zen or any other Dunu for that matter but the Zen Pro, tuning wise, has the mark of a degree of polished perfection consistent with a clear vision and lots of experience. I'm feeling seriously tempted by the Falcon Pro just to experience more Dunu DD magic. The Dunu Zen Pro is my de facto IEM of 2021.



Samples of music used to generate the impressions used in this review: