Nightjar Acoustic Duality

(Pictures to come later)
I have been debating with myself regarding the rating of Duality: on one hand, I would give Duality 6 out of 5 in one category even though it does have its shortcomings; on the other hand, 5 stars should be a perfect score, and Duality is not perfect as you can see from the rest of the review. I finally ended up rating it at 5, not because it is perfect, but because it is just so unique.

Thanks for the watercooler tour arranged by the @Rockwell75 and thanks for @Chang from Nightjar to provide the tour kit, I had the Duality kit with me for 7 days. The kit comes with 2 different cables, one stock cable, one upgrade cable blue hour 2w, an impedance adapter, and a S.M.S.L D10 dongle. The Duality has a dual dynamic driver configuration with two-way crossover design.

As my taste in audio gradually evolves, I find myself still deeply rooted in basshead category. From my collection of IEMs, ranging from Z1R, Trifecta, to XE6, they are all sharing the same fame in their bass performance. I also almost bought EE Legend X and EE Legend EVO for the same reason.

The last IEMs that caught my attention were FatFreq Maestro SE (MSE) and Grand Maestro (GM). In the end, I found MSE being too niche and GM a much better choice. Unfortunately, GM turned out to be a nightmare for fitting to me. It started to hurt after just a few minutes of listening.

Then there comes the Nightjar Acoustic Duality, the latest legend of bass king. I heard so much praise before duality being formally released and finally, I had a chance to listen to Duality during CanJam SoCal 2024. It was a jaw-dropping experience for me. However, the short demo is not enough for me to fully assess the performance of duality other than its unworldly bass.

Fast forward to April 2025, I received a private massage in head-fi that the Duality kit will be coming to me. I have to say that for so many tours I had before, this is one of the most anticipated ones.

In this review, majority of my listening is done with the desktop setup, which is the HiFiMan EF400 on low gain both NOS and OS. I also used ADI-2 DAC to feed Flux FA-10 amp. Both working wonderfully and can achieve the full potential of Duality. I also did several hours long listen with my WM1Z, the volume has increased to 90 and it is still not at the same level as my desktop setup.

How does Duality sound? I have a mixed feeling that Duality is an exceptional specialist, and being so special even in the specialist category, you need the right music genres to make Duality really shine.

The tuning of duality is L shape, but without the too dark or warm feeling of the typical L shape IEMs. This could be one of the secret sauces from Nightjar Acoustic.

First, I have surprises. Before I received the duality, I already had some boiler alert that duality could be a pony of one trick. However, after spending time listening to many different genres, I found that duality is performing well outside the bass category. Although at its current price level, the Mids and Treble could be better, especially compared with its bass, it may bring some disappointment for people expecting a complete TOTL performance from duality.

Another surprise is in the bass itself. I found the bass of duality has one special sauce that I might give 6 out of 5 for its performance: its sub-bass. The reach, the quality, and the quantity of the sub-bass is simply out of this world. So much so that if you put the switch to bass position and use the included impedance adapter, the sub-bass in hip hop will make even the most hard-core bassheads crying out “too much”. Imaging you stop at the traffic light along with a car installed with the sub-woofers, and the driver of that car is playing some very loud hip hop music, and your entire body was physically shaken by the sub-bass. That is what you will be experiencing.

However, my real surprise comes from the mid-bass of duality. The quantity of mid bass is a little shy compared to the sub-bass; I found the bass performance of duality is not consistent as a result. I found either my XE6 or Trifecta more satisfying in mid-bass than duality.

As a result of the tuning and design of duality’s bass performance, extremely powerful bass does not bleed into the mids and make the mids clean and clear. Also because of that, the mids are not as thick as I expected. It could be both good and bad. Good in the sense that duality’s vocal and mids performs wonderfully even with much lifted sub-bass, but bad in the sense that the contrast makes the entire music performance not very consistent.

As a hard-core bass-head, I would like to hear more mid-bass, but I can totally understand Nightjar’s tuning decision to make it so unique.

To sum up the sound impression, Duality has great bass, especially sub-bass, it is absolutely the best among all IEMs I heard so far. The exceptional performance of bass is not achieved by simply lifting a high shelf in the low frequency since the bass also has fantastic quality in terms of texture and details. On the other hand, the mids and treble performance is not at the same level of its bass.

The sound stage is not consistently large. When there is enough bass in the music, you will find the sound stage expends and becomes taller and wider. When there is little bass in the music, the sound stage is not as large.

Duality has very good resolution despite being a bass canon. However, given its tuning, your attention is almost never focused on the detail retrieval.

If you want Duality to be your all-rounder, it is not bad at all, but you will have trouble justifying its price when the music is not the type to make Duality shine. In that sense, Duality is a specialist, it needs the right music to make you feel it is worth its asking price.

Duality is a great choice, if not the best choice for Hip Hop, EDM, or any music with strong bass. When I was listening to Duality in shuffle mode from a highly diversified library, I could clearly see that part of my library (around 40% to 50%) is simply not a good match. However, when the music is right, it really, really shines, it will make you smile and giggle like a child.

Here are some of the tracks I used for duality (thanks for many watercoolers in the thread to provide those tracks, including @zikarus and @goldwerger)

The following two tracks provide enough sub-bass for you to fully enjoy the duality. When I put the impedance adapter on, I quickly took the adapter off my chain since the bass is too much.

Cordae - Jean Michel



Symba - Power Ranger (prod. by Mistersir)



Female vocals are wonderful from duality in the next track

Divine Marina Rebeka climbs up to C6, D6 and Eb6 in Albinoni's Adagio



Male vocals are also very nice as you can hear from the track below:



Here is one example that in many old fashion music, such as the Polk Salad Annie live by Elvis, there are not many sub-bass but the mid-bass punch from duality is not as enjoyable as XE6 or Trifecta:

Elvis Presley - Polk Salad Annie Live



The following track of Indian music may feel a little off because of the lifted sub-bass changes the original balance:

Yeh Jo Des Hai Tera



Another classic track for bass:

Big Boi - Kill Jill ft. Killer Mike, Jeezy



The next few tracks provide more genres for you to see the duality’s performance outside the bass category:

Take Five Kenichi Tsunoda Big Band



Desire ♫ Boz Scaggs



Poetry Man” by Queen Latifah



Djrum - Blue Violet [RS1810]



Another two tracks for mid-bass and sub-bass enjoyment. You can feel the impact from duality is very, very satisfying.

Zaliva-D - Whisper [SVBKVLT]



Bass & Drum Intro (Live)



Jazz Variants (If you are not patient with the build-up, simply fast forward to 6 min)



As expected, Hip Hop is another genre Duality is most suitable for:

Kendrick Lamar - Not Like Us



Some acoustic guitars

Nils Lofgren - Keith Don't Go [CD Quality]



Let’s hear two live performances, Duality again shines:

Electric Love Festival 2024 | Opening Ceremony



David Guetta live @ Tomorrowland 2024



As you can see that my review is based on my desktop setup, which is unusual for an IEM. Unfortunately, my primary DAPs are WM1Z and WM1AM2, neither can drive Duality to its potential, they need a portable amp for that purpose. I also tried with my Hiby RS2, which is much better but still not the level of my desktop setup. For USB dongles, I tried with my DC-Elite and the D10 dongle comes with the tour kit, they are both okay. However, I was using them directly from my laptop. I am pretty sure that if I was using dongle with my cellphone, it would be a totally different story. Unfortunately, this is another big con for Duality. If you are considering buying Duality make sure you have a powerful DAP, or are going to upgrade your DAP, otherwise, you will have to use Duality mostly from your desk.

Finally, I need to mention that tip rolling is very important as Duality has a wide and short stem that makes a perfect seal challenging. I started with the stock tips, and my experience is not good until I changed to my favorite tip AZLA SednaEarfit MAX Standard.

I believe there will be many people who will buy Duality simply because there is nothing like it at this moment. Also from Nightjar Acoustic’s perspective, they have successfully developed a secret weapon that they could later used in the next implementation that will cater for a much broader audience.