Astell&Kern UW100 True Wireless Earphones review

If you’re researching your next pair of wireless headphones and have managed to click your way here, Astell&Kern might not be a familiar name to you if haven’t delved too far yet into the world of high-end audio. However, if you’re more the kind of person who has a bit more of a portable audiophile bent, then the name “Astell&Kern” ought to be synonymous with a couple of distinctive house traits: an uncompromising approach to delivering high-end sound; and utterly distinctive industrial design. 

The South Korean maker has made their mark on the head-fi world thanks to their range of high-end wired headphones and IEMs, and even more so when it comes to their industry-leading Digital Audio Players, or “DAPs”. So it came as somewhat of a surprise that Astell&Kern announced that they’ve thrown their hat into the hyper-competitive ring of true wireless earphones with the release of the brand new $399 Astell&Kern UW100 True Wireless Earphones. Sensing that their was a gap in the market when it comes to a truly audiophile-oriented true wireless IEM squarely aimed at delivering uncompromised sound quality, Astell&Kern went about squeezing all their hard-worn know-how from their digital players and wired earphones into one svelte wireless package. And of course, Astell&Kern being Astell&Kern, they’ve managed to make the new UW100 look quite unlike anything else on the market. 

A True Wireless IEM for the portable connoisseur 

Astell&Kern has promised that their new UW100 delivers “immersive best-in-class hi-grade sound” - when the rest of the market has been focused on delivering true wireless products that offer all-round utility with “sound quality” being a few notches down the feature-list, their decision to release a “sound-first” true wireless product suddenly doesn’t seem all that surprising at all. If you’ve been on the fence about “going wireless” due to the lack of a true audiophile-oriented offering, then you’d better pay attention to what the new UW100 offers, because it’s entirely different to anything else on the market both in terms of design philosophy as well as performance. 

A pair of the new UW100 landed on my door step for review last week, and with a busy week of travel, work, life, and my usual schedule of music listening planned, it turned out to be the perfect real-life test scenario for Astell&Kern’s new true wireless offering. I’ll spoil things right away by saying that I’m more than impressed by the new UW100 - there’s no question that they’ll be my go-to wireless listening companion of choice for the foreseeable future. But before we talk about what they’re like to live with, we’d better take a look at what makes the new Astell&Kern UW100 different. 

Astell&Kern AK UW100’s key features at a glance:

  • Dedicated, high performance AK4332 32-bit hi-fi grade DAC.

  • aptX™ Adaptive wireless codec for low latency and support for 24-bit audio quality.

  • Features Bluetooth 5.2 wireless technology for a more stable connection.

  • Knowles Balanced Armature drivers deliver ultra-detailed sound.

  • Best-in-class passive noise isolation (PNI) with ambient mode.

  • Battery: 6 hours playback, 18 hours from the case (24 hours total).

  • Case supports wireless and fast charging.

  • Touch controls for easy control on-the-move.

  • Proprietary iOS and Android app for customisation.

On-board digital smarts 

Any device that handles digital audio, be it a CD player, laptop, or smartphone, has a digital-to-analogue converter (or “DAC”) onboard to convert the 1’s and 0’s into analogue sound. And that’s also true when it comes to true wireless earphones - each one of those two tiny earbuds has a small DAC chip onboard to take a wireless digital signal and turn it into music. The problem is, in most cases, that a less-than-optimal DAC chip has been jammed inside - usually they’re integrated into the Bluetooth chipset itself which is tasked with doing all sorts of digital duties besides audio reproduction. 

Astell&Kern, having had years of experience with implementing high-end DACs into their digital products decided that their first true wireless deserved nothing less than a separate DAC chip dedicated solely to providing first-rate sound quality. In the case of the UW100, Astell&Kern chose the AK4332 DAC/amp chipset, capable of 32-bit digital performance as well as having an integrated Class-G headphone amplifier capable of 88 mW of power into an 8-ohm driver. Unlike traditional true wireless designs, the AK4332 is sandwiched in-between the UW100’s Bluetooth chip and driver, decoding either PCM or DSD data and amplifying it into the drivers. 

Being an entirely wireless-dependent product, Astell&Kern has equipped their new UW100 with the latest Bluetooth 5.2 technology, which is capable of receiving larger amounts of information over lower bandwidth and at lower power, meaning greater performance with lower battery drain. The UW100 features Qualcomm’s QCC5141 chipset with support for the the high-quality aptX Adaptive codec, which adapts the bit-rate appropriately for the signal being received to ensure the best combination of audio fidelity and reducing latency. Apple users will need to settle for the AAC codec, however, it should be noted. 

The UW100 also supports Multi-Point and Multi-Pairing functionality, meaning that you can have two different devices paired at the same time. This proved useful when I had them paired with my MacBook for a bit of YouTube viewing, all the while staying connected to my phone to receive calls and notifications. 

Balanced armature drivers

Whereas most true wireless IEMs employ a traditional single dynamic driver to handle full-range frequency playback, Astell&Kern has chosen a single Knowles Balanced Armature driver for use in the UW100. Having had long experience implementing multiple driver IEMs, Astell&Kern opted for a single balanced armature driver configuration to deliver what they felt would be a more detailed performance compared to the more commonly-used dynamic driver. And given that a battery, AK4332 DAC chips and other related electrical components all needed to be squeezed into a compact shell, the single armature driver configuration also presumably helps to minimise space by avoiding complicated crossover networks. 

A focus on passive noise isolation

Many competing true wireless products in the price-range of the UW100 make a deliberate point of both providing and advertising integrated Active Noise Cancellation (ANC) as a key offering. However, Astell&Kern have deliberately pointed out that they have avoided ANC in the design of the UW100. Active Noise Cancellation requires a wireless earphone to use its inbuilt microphones to receive external noise, which is then “cancelled” by emitting an opposite-sounding noise via digital signal processing. Astell&Kern explains that they decided to avoid ANC as they felt it actually degrades audio performance, and having spent some time with ANC-equipped wireless products, I can understand this decision - when you switch noise-cancelling on or off, things usually sound…different

Instead, Astell&Kern concentrated on providing the best passive noise isolation possible in the UW100. Passive noise isolation is simply the ability to reduce ambient noise by physically blocking it from entering your ear, and many IEMs can do a great job of blocking out the outside world thanks to simply having a snug fit. Astell&Kern reckon the UW100 can work nearly as well as an ANC-equipped IEM in most circumstances, and even better when it comes to mid-range and higher frequencies. They rate the UW100 as being able to reduce frequencies at 100hZ by -22db; 500hZ by -33dB; and 2kHz by -41dB respectively. 

Unboxing the UW100

The UW100 arrives in a small, glossy premium display box that tells you that a pair of “Ultimate Wireless Sound Earbuds” are housed within. Inside, you’ll find a Quick Start guide, warranty documentation, a short USB-c cable for charging, a generous five sets of silicone eartips, plus the UW100 earbuds themselves safely stored inside their companion storage/charging case.

It’s a fairly uncomplicated and streamlined experience as far as unboxing and accessories go, but then again we’re talking about a very compact product that you’re never likely to need to put back in the box again once you take the case out and start using them in your daily routine. 

The UW100’s case is slightly on the larger side as true wireless IEMs go - it only weighs 65 grams, but being slightly “tall” it might make for a bit of a bulge in your back pocket. The case itself is classic Astell&Kern, with an angular trapezoidal design on the brushed silver plastic finish on its lid, along with their “A” logo. It has a strong, magnetised lid which I guarantee will never accidentally open itself while bumping around in the overhead compartment on a bumpy plane-ride.

The case functions as the charger for the UW100 earbuds themselves, and is powered via a small USB-c port on the rear. One feature that I LOVE about the case is the fact that it’s compatible with fast chargers as well as wireless chargers. As someone with a wireless charging pad on my desktop and bedside, you simply pop it on top, and it’s charging - great. 

UW100 design and form factor

The angular, trapezoidal theme continues when you open the case with the UW100 earbuds themselves - the outer face of the shells have the same brushed plastic finish, and also house the inbuilt microphones and touch-sensitive controls for managing the most important user interactions with the earbuds. 

The UW100 is a fraction larger than most true wireless earbuds that you might have encountered previously - they have an unusual pentagonal shape, and the main body of them is about 1cm deep. However, they only weight 7 grams apiece, and that unusual pentagonal shape actually fits extremely well into your inner ear.

The inner side of the shells are made from a comfortable, contoured plastic finish that somehow manages to barely touch your ears at all, since the friction of the supplied silicone tips do all the work when it comes to keeping the UW100 firmly in place. With five different sets of tips supplied, you ought to be able to find a fit that’s right for you - the second largest ones worked great for me. 

UW100 user experience

A day-trip from Sydney to Brisbane felt like the perfect opportunity to get acquainted with the new Astell&Kern true wireless earphones. With an hour flight each way, and a bunch of phone calls and video meetings scheduled, it turned out to be a good insight into what the UW100 is like to live with, and how it performs in the real world. 

Arriving 45 minutes ahead of schedule, I parked myself in the lounge with some tea and toast and went about getting myself familiarised with the UW100. The UW100 is ready to pair right out of the box - I was a simple case of taking them out of the charging case, popping them in ears and selecting them from the available Bluetooth devices from my Pixel 6, which confirmed that the UW100 was ready to receive Qualcomm aptX HD Audio. A friendly AI voice (that reminds me a bit of the Battle Droids from the Star Wars prequels), confirmed that everything was hooked-up and ready to roll with a mix of high-definition music from Qobuz and Youtube videos videos. The UW100’s Bluetooth connection with both my MacBook and Pixel 6 were strong - I haven’t experienced a single stutter or drop-out during day-to-day usage as yet, and I had to walk pretty far across the Sydney Virgin Lounge before the connection started to break-up.

Next, I installed Astell&Kern’s dedicated “AK TWS” companion app for the UW100, which is available on both iOS and Android and allows you to manage some key settings; monitor battery levels; and presumably manage on-air firmware updates down the track. Included in the app is a run-down of the gesture-controls for the touch panels on each earbud (which can also be configured inside the app):

  • One tap on the right hand side for play/pause and connecting/disconnecting calls 
  • One tap on the left hand side for turning “ambient mode” on/off
  • Two taps on the right hand side for next track
  • Two taps on the left hand side for ambient mode control
  • Three taps on the right hand side for previous track
  • Three taps on the left hand side for Google Assistant
  • Three second hold on the right hand side for volume up
  • Three second hold on the left hand side for volume down
  • Three+ second hold on either side to enter pairing mode 

The touch controls on the UW100 are reliable, intuitive, and easy to use after a spending an album or so’s worth of time with them. A simple “tap” with your finger or palm is easily registered, and I didn’t find myself getting frustrated by accidentally stopping my music in the middle of a song like I have with other devices which can be triggered simply by brushing against your clothing. 


“Ambient mode” allows you to let a bit of the outside world in, should you need to stay aware of what’s going around you - like when your flight to Brisbane is boarding! The app gives you the choice of four different levels of ambient sound, and I can see it being useful to some people in particular circumstances. Most ambient mode-equipped headphones do create a bit of a strange hyper-detailed sense of outside world, and the UW100 is no different here. There’s a slight amount of latency if you click your fingers while it’s on, but this mode is more for utility rather than for music enjoyment so I expect most owners will use it sparingly. 

The AK TWS app also gives you access to four different EQ settings. “Bass emphasis” mode does just that - it emphasises the UW100’s low end rather drastically, which can be fun for some people, I guess, but it’s just too much for me - it starts to break up and get distorted in particularly bass-y music. “High Emphasis” cuts the low end and adds a shrill emphasis to the treble; “Vocal Emphasis” adds a boxy, telephonic quality to the lower treble; while “Game Mode” creates a more forward mid-range plus added detail in the “presence” region, presumably to help convey the detail of footsteps and other important sounds in gaming. I didn’t find any of the EQ presets to be particularly enjoyable or useful for my circumstances, but then again, the UW100 is tuned pretty damn well as I’ll focus on later. Hopefully, Astell&Kern will add a little more customisability to the app down the track with users able to tinker with individual frequency bands. 

Having jumped on the plane and settled in my seat for take-off, I was keen to see how well the UW100’s passive noise fared when it came to the gold-standard test for noise reduction: air travel. With music playing at a moderate level, the UW100 did a pretty admirable job of blocking conversation from other passengers around me as well as announcements from the flight crew. The low, constant noise from aircraft engines was still audible, but fairly well mitigated - a good ANC implementation will do better with lower frequencies, but the UW100 will be more than adequate for the casual traveller who plans on doing more listening with their feet planted firmly on the ground. 

Astell&Kern claims that the battery in the UW100 can manage up to six hours of playback on a single charge, which can be extended to a full 24 hours when using the charge stored in their case. A ten-minute quick charge in the case can fuel the UW100 with an additional hour’s worth of playback. With about three hour’s worth of mixed use between music, video, and phone calls, the AK TWS app informed me that the left and right earbuds were sitting at 50% and 52% charge respectively, which tells me that the 6 hours feels very much achievable. 

I had to make several voice and video calls throughout the day, and the UW100 didn’t skip a beat - voices were clear and intelligible, and the people on the other end of the call were happy to oblige and let me know that I was coming through clearly on the other end through the inbuilt microphones on the UW100. 

Back home later that week, I wanted to see how the UW100 fared when it came to riding along on a jog along the Clovelly to Bondi coastline on Sydney’s Eastern beaches. The silicone tips provide a pretty secure fit without the need for additional hooks or loops, but being slightly larger than most true wireless earbuds I did find that I’d have to re-lodge them in my ears a couple of times to make sure they stayed-put while pounding the pavement. Sure, the UW100 is aimed more at music fans than it is at gym-junkies, but they’re definitely up to the task. 

Listening to the UW100

The UW100 is at first a departure from the type of sound that you’re used to when dealing with your classic dynamic-driver true wireless IEMs - they don’t have an omni-present mid-bass warmth or overly rich tone, and nor does the UW100 have a tapered-off, gentle treble department. Instead, the UW100 quickly gave me the impression that they’re a trifle more articulate, and a whole lot more detailed and spacious than any wireless earbud I’ve encountered. 

“Uneventful Days” by Beck was first up on my Qobuz mixtape, and it showed the UW100 to have plentiful bass for a single balanced armature IEM. The UW100 has plenty of taut definition in the lowest octave with seriously impressive extension that I wasn’t expecting at all. Multi-driver IEMs usually employ one larger armature or a dynamic driver to handle lower frequencies, but Astell&Kern has done wonders here with one single full-range armature. I suspect a little digital signal processing might be in play here, but no matter how it’s been achieved, it’s well-implemented. 

The next track on Beck’s Hyperspace album, “Saw Lightning” made the other standout feature of the UW100’s tuning come to the forefront - a genuinely spacious and airy treble with appreciable levels of detail. The UW100 throws a believable and impressively diffuse soundstage for an IEM, and does a great job of putting individual tracks beyond your head on a left/right plane, but not especially deep in a front-to-back sense. 

It’s refreshing to have some actual treble detail and nuance in a wireless IEM, and it helps give them what I call a more audiophile-neutral-bordering-on-warm presentation as opposed to your classic consumer bass-heavy/V-shaped tuning. Some cymbal and upper treble notes can sound a little “splashy” at times in poorer recordings, but with well-recorded tracks the UW100 simply offers a terrifically transparent window that digs deep into the nuances of a recording. 

A slight recession in lower the UW100’s lower treble makes male voices and some instruments take a step back from the mic, but this does make the UW100 sound less “immediate” and adds to the overall sense of stage - especially in well-produced tracks with lots of individual instruments and multi-tracked vocals like Fleet Foxes’ “Can I Believe You”, where the UW100 does an admirable job of conveying the resonance of the acoustic instruments and vocals in a large recording space. 

Although I was a little skeptical at first, the decision to use a single armature over a dynamic driver has paid off here - the UW100 is a lot more light-footed and detailed-sounding than pretty much any other true wireless IEM I’ve encountered to-date. And while it does have a slightly drier, snappier tone and more smoothed-over, subtler dynamics, the UW100 has an altogether more “grown-up” sound as a result of its driver and tuning implementation that is a truer reflection of what you’re playing. 

Final thoughts

There’s something pretty cool about knowing that the manufacturers of your wireless earbuds have gone to the trouble of squeezing a 32-bit capable AKM DAC inside, and that says plenty about the way that Astell&Kern has gone about designing an audiophile-oriented true wireless IEM from the ground up. 

Creating a product with a specific audience requires sacrifice in some areas, and the UW100 does forgo a couple of boxes like active noise cancellation and an IPX water resistance rating that are normally ticked in other wireless earbuds that are intended for use with multimedia, productivity and communications as much as they are for music. However, the listener who places sound quality first, second, and third on the list of features simply cannot walk past the Astell&Kern UW100.

Their classy, articulate sound and decidedly “different” look place them head-and-shoulders above the rest of the wireless earbud pack, and the fact that they’re actually great to live with day-to-day makes them an all-round delight. I can see them becoming an essential part of “everyday carry” lists for busy, discerning audiophiles who like to leave the house, and are ready to leave the cable behind too!

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