Fit and Comfort

Seen above is the right channel of the Dunu x Precogvision Mirai placed into an artificial ear mold with the included size M white silicone ear tip installed. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing, since foam tips are not included by some brands, and I found these tips to work fine enough even if they were slightly stiffer than I personally prefer. These are quite consistent in sounding well with all DUNU IEMs I have here and also measure as I perceive them too. The Mirai is a larger-than-average sized set that will jut out of the ears for pretty much everyone. This is more to do with the thickness of the shells than the contact surface area inside which itself is going to be agreeable to most people. Having a longer nozzle which is thankfully not as wide as many IEMs these days have is also helpful in achieving a good and secure seal, although you may want to play around with how deep a seal you achieve since this can impact the upper treble energy presented by the Mirai. This is also why I urge you to try different tips even if you get the first set to work fine as the Mirai is quite tip-sensitive and you may be too. The shells themselves have plenty of contact in the concha for support courtesy the semi-ergonomic fit and the cable can help further—especially if you route it around the back of the head or at least use the cinch under the chin to secure it in place. The shells being made of resin also means there isn't any physical fatigue from weight—6 g per side—either.

Audio Performance

Audio Hardware

The Dunu x Precogvision Mirai employs a hybrid driver configuration in that there are two different driver types here for a total of seven drivers per side. The parties involved in this collaboration went for a traditional hybrid driver implementation to keep things less complicated with one 10 mm dynamic driver handling the bass and the rest being balanced armature drivers. The dynamic driver employs some of DUNU's technologies by going for a composite diaphragm with biocellulose dome and a fully independent surround. A dual Sonion BA is used for the mids with a Knowles BA handling the transition from the mids to highs before more Knowles BA tweeters take over in the form of a dual tweeter and a newly developed open-back super tweeter for the ultra highs. While we don't get the exact driver details, I suspect this last driver was the same one which was under exclusive contract to another IEM brand for an year before others were allowed to use it and the design seems similar to 64 Audio's tia driver in what it does. The end result of this 5-way passive crossover design is a set of IEMs with average rated impedance of 25 Ω (at 1 kHz) and sensitivity of 111 dB/mW (presumably, DUNU still hasn't figured out how units work) making the Mirai extremely easy to drive off even a halfway decent dongle, let alone a more powerful portable DAC/amp for use on the go. There is no need to go with the balanced connectors thus unless you just like how the 4.4 mm connector looks and feels.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature with a slightly elevated bass, smooth treble range, detailed mids, and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through a capable and transparent DAC/amp—I used the Questyle M15 here. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the Dunu x Precogvision Mirai. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are basically identical across the entire useful 20 Hz to 20 kHz range! Keep in mind that this is a specially designated review unit but DUNU is known for its more stringent quality checks and thus seeing this level of excellent channel matching on one of its more expensive sets isn't a surprise—I expect all retail units will be similarly impressive. Measurements taken after 50 hours of testing, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the anthropomorphic pinna in place matched the ideal scenario in the coupler extremely well too and this is an indicator of how good the fit and seal was when installed in the artificial ear. But keep in mind that the pinna doesn't care about any comfort issues, so your mileage may vary in your actual ears—especially given the Mirai is more sensitive to ear tips and how deep you fit it in your ear canals than the average set of IEMs.



Here is the average frequency response for both channels of the Dunu x Precogvision Mirai plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. This is in addition to a second graph using a newer target that's based on a more scientific methodology involving a -10 dB tilt (-1 dB/octave) applied to the diffuse field target for the newer, more reliable B&K 5128 but then compensated for my exact 711 coupler instead. Do scroll down to the targets in my database linked above and see the new 5128 section to the left where you can click on the yellow question mark for a brief primer. The bottom line is this target is closer to what many people are likely to prefer out of IEMs and headphones alike. I have chosen to plot this graph with the frequency response normalized/compensated to the target to make it easier to see where the Mirai deviates from this target. This helps visualize the various elements of the set's tonality—U-shaped but without recessed mids, almost to the point of being a colored take on neutrality but with nuances galore in bass, upper mids, and treble alike.

DUNU, Precogvision, and a handful of others in the know took over two years to develop and tune the Mirai to its current status. As mentioned here, there were several prototypes which came about owing to regional preference disparities, among other things. They'd probably also not want me to say this but the Mirai was originally not going to cost this much and was going to be a much simpler set in terms of the design and drivers used. All these iterations happened in order to meet, and seemingly also exceed, the requirements of everyone involved in this collaboration. You can see how the tonality feels safe at first glance—especially without any other set in there as a comparison. There's the expected bass shelf rising predominantly from 250 Hz going down measuring ~10 dB up at 20 Hz compared to the mids. The ear gain begins earlier than average at ~800 Hz in accordance to prevalent audio science and peaks around 2.5 kHz before having a series of dips and rises eventually resulting in fairly excellent treble extension all the way to 20 kHz. It's what happens in the middle of all these that makes the Mirai less of an all-rounder set and more of an uncommon add-on to a collection.

The bass shelf is such that it's more sub-bass focused than on the mid-bass. Expect more thump in your head with electronic music than the boom of drums and bass guitars thus. The Mirai may be found wanting for classic rock music aficionados and instead be more like your personal night club for EDM and house/trance music. I can see people finding the Mirai still on the leaner side for bass though and thankfully the set does take very well to EQ. However, the bass bump starting from 250 Hz instead of the usual 200 Hz for sub-bass tuned IEMs made a big difference to me. I found the Mirai to have plenty of impact, lots of detail, a very competitive dynamic range for the asking price, and yet presenting clean mids without the bass muddying things up. This in turn makes the Mirai a plausible set of monitors for mid-heads given the ample room for instruments and vocals throughout. I also appreciated that the Mirai does not actually have recessed mids despite emphasis on either end in this U-shaped tonality. This resulted in forward-facing vocals and instrument fundamentals all getting their due with precise imaging in a wide cone in front of you.

The ear gain region might measure like it peaks at 2.5 kHz here but in practice it might feel different depending on the fit and insertion depth achieved. The earlier peak here is with a deeper insertion in the coupler and this was arguably even more controlled than the bass in presenting female vocals distinctly without coming off honky/nasal. A narrower insertion shifted things to the right slightly and sounded better to me in terms of vocals and strings not coming off overly forward, but here it will come down to your particular HRTF and how you perceive the sound. It might be more up your alley if you prefer K/Jpop music maybe as opposed to R&B and jazz. Then the Mirai does something I've not seen in a lot of IEMs in this price range, effectively taking cues from far more expensive sets, in handling the upper mids/highs transition. Those deliberately placed peaks and dips keep things from not only being fatiguing for longer listening sessions but also helps with that precise imaging aforementioned. Second-order harmonics for brass and string instruments as well as piano keys get their dues resulting in a satisfying listen for orchestral and classical music, especially given the excellent detail retrieval in the treble. There's some air in the upper treble to keep things fun and add to a wider soundstage, especially if you perceive it, yet not enough to be jarring and affect timbre in a negative manner. This is also where I was impressed with the overall control the Mirai exhibits, but be warned that the tips and insertion depth change things more than you might expect. Some might find the super-tweeter to be fairly aggressive, once again reminding me of 64 Audio's tia driver, which can be irritating as well as give a metallic twang to cymbals, harps, violins, and triangles. In this case, do try out different tips and play around with insertion depth as long as you don't break the seal. The Mirai reminds me of some excellent IEMs which cost significantly more in its technical performance, but does so by going for a tonality which may not be for everyone or suit your specific music preferences.


The DUNU x Precogvision Mirai is a kilobuck set and there is a lot of competition in this price range. It also happens to be the most expensive DUNU IEMs I've reviewed to date, so much so that the others are in a too different a price segment altogether to be discussed here. Instead, I decided to focus on some sets I know the Mirai is likely to be compared against. Take the 64 Audio U4s, for example. Precogvision is known for his preference of the 64 Audio house sound and feature set, so no doubt many who are interested in this set are also wanting to know how the Mirai compares to the U4s, the U6t, and perhaps even a U12t. I don't have the latter here and the U12t is not worth the money over the U4s as far as I am concerned so we go back to the 1 DD, 3 BA U4s which is not as dynamic or engaging as the Mirai in the bass and is also less resolving throughout. The U4s does have a more substantial mid-bass presence though, at least with the m15 and m20 apex modules. Those modules help change the bass response and overall tonal balance which can be neat but you no longer get the m12 module with the packaging and this is a big loss since that combination made for a much cleaner sound that competes more favorably against the Mirai. The tia driver in the upper treble is less responsive to tips and fit so that can be good or bad depending on how the Mirai works for you. I'll also give 64 Audio the win when it comes to fit and comfort in general and perhaps the metal shells of the U4s might feel more substantial over resin. The Mirai has far better accessories though and I'd be hard pressed to pick one over the other. I might go U4s given it can be more of an all-rounder with the apex modules, but the Mirai is a better set of IEMs overall.

ThieAudio has a bunch of IEMs priced similarly to the Mirai, including the Prestige LTD, the Hype 10, the V16 Divinity, and two separate Monarchs. The latest, and the most popular of the lot based on recent sales, is the ThieAudio Monarch MKIII which opts for a tribrid driver configuration featuring two dynamic drivers, six balanced armature drivers, and two electrostatic tweeters. I'd argue there is a case to be made about open-back BA drivers to be potentially considered their own driver category but either way let me remind you the driver count and type doesn't matter as much as what the IEM manufacturer does with them. The Monarch MKIII is an all-resin shell set with customizable face plates and shells which is a neat option for aesthetic preferences. It's also on the larger side, including with the nozzle, to the point where the Mirai is actually easier to fit in the ears. The Monarch MKIII also goes for more mid-bass presence and is more U-shaped than the Mirai with its pronounced treble energy also. I appreciate what ThieAudio is going for here but ultimately thought the overall listening experience wasn't worth the asking price. It's not as clean as the Mirai, certainly not as resolving, has a narrower soundstage, and the treble response comes off uneven and potentially fatiguing, if not annoying. I do think it handles male vocals as well as the Mirai but easily fades away with female vocals that have less character, perhaps owing to the specific nature of the upper mids tonality of the Mirai compared to the Monarch MKIII. Accessories and build quality is a wash here so I'll give the win to DUNU and Precogvision for this round.

The Symphonium Audio Helios is an excellent set which bucks the trend of Harman-style IEMs sounding all the same and mostly boring. It still has a bass tuck which hurts mid-bass and impact of drums and guitars though and the tonality makes it even less of an all-rounder set than the Mirai. But there's something magical about the Helios' treble execution which gets me to pull it out for when I am in the mood for some Bach or some orchestral recordings. Then I remember how poor the comfort and fit is, despite a decent seal, and why I don't listen to it more often. There is a limited edition Helios SE which uses smaller shells and is more likely to appeal to the masses over the Helios, but I'd argue neither are really meant for the masses anyway and the Helios still does treble better. Between these quality-of-life and tonality concerns, the Mirai is my winner here. Perhaps the newer Symphonium Crimson is worth checking out also but I have only heard it at an audio show so I can't speak more about it unfortunately. It also happens to cost $400 more so perhaps that's irrelevant anyway. There are plenty of other ~$1000 IEMs on the market, such as the Custom Art FIBAE 5 with its Knowles damper-based customizable DD bass, BA mids, and a micro-planar driver for treble. It is best seen as an eccentric set these days though wherein I am not sure the feature set and tonality is going to be a top recommendation anymore. In particular, the upper mids and treble can come off quite hot and peaky to be fatiguing and the treble quality and timbre can be hit or miss. It does work quite well for a few music genres and the adjustable bass shelf would have been worth talking more about but ultimately it's another set that feels relegated to the "seems cool, but not sure it adds much to my collection" viewpoint. Both DUNU and Precogvision could have easily strayed too far down the amenable tonality route with the Mirai but thankfully found a coherent balance that works well enough to not become one of these sets.