Today, I'm reviewing the Luna, a pair of earphones born from the collaboration between Astell&Kern and MADOO.
Astell&Kern has consistently delivered outstanding results in the DAP (digital audio player) market. However, the same can't quite be said for their earphones. That might sound like a controversial statement to some, but if you take a closer look, many of the earphones people associate with Astell&Kern’s success were actually the result of collaborations with other well-known IEM brands. On their own, Astell&Kern's in-house earphones have never really achieved the same level of acclaim.
In that sense, perhaps it's a relief that the Luna was also developed in collaboration—this time with Japan’s MADOO. The Luna features a 13mm unipolar micro planar magnetic driver, co-developed with MADOO. The name might sound technical and complex, but simply put, it’s a planar driver with magnets positioned only on one side of the diaphragm.
One of my initial concerns about the Luna was the fact that it's a single-driver earphone. And yet, in true Astell&Kern fashion, the price is extremely high. When a product commands such a premium, consumers expect something to justify the cost—typically a complex design or multi-driver configuration. A single-driver setup doesn’t offer that kind of immediate justification. Of course, this isn’t about raw manufacturing costs; it’s not as though stuffing a dozen BA drivers into a shell automatically makes the product much more expensive to produce.
At the very least, the Luna’s design and build quality do live up to its premium price. The CNC-machined titanium housing not only looks solid, but also feels incredibly refined to the touch. Thanks to the single-driver configuration, the shells aren’t particularly large either, which contributes to excellent wearing comfort. Personally, one of my favorite aspects is the connection between the earphones and the cable. As a dedicated, custom-designed cable, it integrates seamlessly with the housings. The stock cable itself is of outstanding quality, and for that reason alone, I have no intention of swapping it out for an aftermarket one.
What I appreciate about planar drivers is their ability to deliver a wide and consistent frequency response with just a single unit. Dynamic drivers often fall short in the treble region, while a single BA driver typically lacks sufficient bandwidth. Taking those factors into account, if you’re going to use only one driver, a planar is the most capable choice.
Let’s take a quick look at the Luna’s specifications: a frequency response of 20Hz to 30kHz, an impedance of 5 ohms, and a sensitivity of 105dB. While the sensitivity is relatively low, there shouldn’t be any major issues if you’re pairing it with a competent DAP. I used it with Astell&Kern’s own PD10 for this review. The packaging and included accessories are also top-notch, but I won’t go into too much detail on those here.
Sound
The first thing I have to say is this: when I first opened the Luna and gave it a listen, I was a bit disappointed. The sound didn’t seem to open up properly—it felt somehow blocked or constrained. I wondered, Is this the limitation of a single driver? or Was the tuning off? Whatever the case, it didn’t sound like something worthy of its price tag.
If you stop reading here, the Luna might sound like a problematic earphone. But don’t jump to conclusions just yet—keep reading. I’m not usually someone who puts much emphasis on burn-in when it comes to earphones. But there are a few models where the difference before and after burn-in is undeniably noticeable. In my opinion, the Luna is one of those cases.
That said, it doesn’t take long. Just one day. Let music play through the Luna for a full day, and you’ll find it transforms into a completely different earphone.
It’s as if the music clears away some unseen layer of packaging inside the Luna. The congestion disappears. The sound stretches out freely, expanding left and right with ease. If I had to describe the Luna’s sound in a single word, it would be “high-performance.” That speaks to the driver’s capabilities—especially important in a single-driver earphone like this one. I suspect the titanium housing, which likely helps suppress unwanted vibrations, is also playing its part effectively.
By coincidence, I’ve also been listening to several other earphones around the same price range—or even more expensive—at the same time. Each has a strong, distinctive character. But the Luna stands out in one specific area: clarity—an unmistakable sense of purity and cleanliness in the sound.
With high-end earphones, individuality is essential—of course, in a good way. Many recent flagship IEMs seem to strive for a sound that feels less like an earphone and more like something grander. They aim to be wider, more three-dimensional, more majestic—almost as if you were listening through full-sized headphones. And I enjoy that kind of sound, too.
But the Luna is different. It sounds like an earphone—and a very, very good one at that. The sound is clear, clean, and precise. It doesn’t artificially try to exaggerate scale, nor does it push to create an overly deep soundstage. Instead, it presents just enough layering to express the music’s dimensionality without overreaching.
Let’s imagine you’re listening to a full orchestral piece. With so many instruments playing together and with the hall’s natural acoustics coming into play, a wide and spatial presentation becomes important. In terms of depth, the Luna falls slightly short—it doesn’t reach as deeply into the soundstage as some others do. But because the imaging is so precise and the instrument positions so well-defined, there’s no sense of congestion. Even with complex orchestral arrangements, the Luna never feels overwhelmed.
When it comes to piano or violin concertos, I actually found myself loving the Luna. The tonal balance between instruments is simply fantastic. Personally, I especially enjoy the way the Luna renders piano timbre. So, while the Luna may not be the best match for listeners who crave expansive hall ambiance and grand staging, I believe it will be a perfect match for those who prefer to focus on each individual instrument in fine detail.
Earlier, I described the Luna as “high-performance”—and I stand by that. Fast-paced tracks, tight low-end, complex compositions—no matter the genre, the Luna handles it all with ease. Perhaps my impression is even stronger because I’ve recently been listening to IEMs that are quite different from the Luna in character. And now that summer has fully arrived in South Korea—with all its heat and humidity—the Luna’s crisp, refreshing sound feels even more fitting. It’s like an audio version of a cold, fizzy drink.
Don’t get me wrong, though. I’m not saying the Luna sounds “bright” just because it’s tilted toward the upper mids. That’s not what gives it that refreshing character. It comes from its precise beat articulation and clean note edges. The tonal balance is excellent—so long as you're not someone who’s used to the kind of massive, weighty low-end that’s trendy these days. Luna’s tuning is more like a pair of monitor speakers on a desk—accurate and poised. That said, there is a noticeable graininess in the upper-midrange. Depending on the track, it can sometimes come across as a bit rough or edgy.
If there’s one real drawback, it’s the price. That’s the first thing anyone would mention. Had the Luna launched at a price even $1,000 lower, I might have called it a game-changer. That said, even at its current premium price, the Luna offers genuine value by smartly diverging from the tuning trends that dominate the current high-end IEM market.
As for the rest—it’s more about personal preference than objective faults. For listeners who expect their flagship earphones to deliver a grand sense of scale, the Luna may not be the ideal fit—especially in terms of depth. And for some, the upper mids might come off a little bright, though that’s likely due to the relatively restrained low-end.
Conclusion
It’s never easy to recommend an earphone at this price point. However, for those who collect earphones in this tier, the Luna could very well be a unique addition that stands apart from what they already own—yet still functions as a highly versatile all-rounder.
Astell&Kern’s Luna delivers a textbook example of refined, reference-style tuning. Solid, confident, and unmistakably well-crafted.