64 Audio U18s Review

Since its release, the A18s has been a favorite custom model among 64 Audio fans, and the U18s brings that custom designed greatness to a universal fit IEM. With a fresh new design, and a $2999 price tag, can the U18s hang with the best of the best universal IEMs?

The Build and Design

The U18s is a departure from the styling of 64 Audio’s previous universal fit IEMs. The general shape and body contours feel familiar, but the textured faceplate completely devoid of a 64 Audio logo is a first. While the Nio might have a flashier design, the A18s is in some ways a more radical departure from the fold in terms of looks. It also includes 64 Audio’s excellent 8-Braid Silver Cable (technically silver plated copper) rather than the standard thin black cable we’ve become accustomed to.

64 Audio U18s

The package contains the IEMs, premium cable, case, Apex modules, and a selection of silicone and foam eartips. The eartips are presented on a very cool eartip organizer that would be really nice to keep handy. The U18s includes mX, m15, and m20 Apex modules, which are used to adjust the isolation of the IEMs. The mX has the least isolation, and m20 has the most, with the m15 (what’s installed out of the box) falling in the middle.

In terms of fit and comfort, I’ve personally always found 64 Audio IEMs to be a comfortable, easy fit, and the U18s is no exception. The stems are on the longer side, which can be challenging for some people, and the overall shell is a little bit bigger than the U12t or Tia Trio, making for a slighter more challenging fit. However, the IEMs are overall moderately sized, and still beg the question of how they even fit all 18 drivers in there.

The Sound

The U18s creates a transportive experience, as it delivers an expansive, impeccably detailed 3D image, with a natural, realistic reproduction of sound. The tuning, at its most basic level, is like a reference tuning with a bit of a shelf that’s elevated in the low end, reaching down to the subbass, and a smaller one pushing up into the treble. It feels mostly neutral, but then you get that little bit of extra low-end rumble, or perhaps a touch of air that lends a heightened sense of musicality to an honest, accurate tuning.

The bass is some of the most physical that I’ve heard from balanced armature drivers, with a great sense of depth, impact, and color. The mid bass has an excellent sense of thump and impact without ever becoming bloated or flabby, and there’s great extension to the lowest lows that can create a visceral rumble.

64 Audio U18s

The mids are well sculpted, with good vocal and instrumental presence, as well as plenty of detail and texture. They sit slightly back from the bass and treble, but don’t feel strongly recessed. The balance provides exquisite detail along with strong cohesion.

The treble is liquidy smooth with a touch of air. Cymbals have a good splash and just a touch of bite, while instruments like guitars and violins that push up into the highest registers feel powerful, but just a little smooth at the top, avoiding too much bite or sibilance.

It’s hard to talk about the soundstage and imaging separately with the U18s, because the complete 3D image feels very much like a cohesive whole. There’s a large, well rounded sense of space, like a three dimensional canvas with good depth, width, and height, and each song paints performers and instruments onto that canvas, with a sense of space and sound within that space that feels realistic with an immersive, holographic presentation.

On Medeski, Martin, Scofield, and Wood’s “North London” you get a sense for the way the U18s builds layers with it’s space. The guitar groove starts out in the middle, and the bass and drums come in, providing support underneath the groove, while the organ comes in alongside the guitar. As the guitar and organ trade melodies, there’s a subtle sense of one or the other moving closer. You can easily pick apart the layers in your head, with each one, having depth and texture, and an array of subtle details to pick out – from the individual performance techniques to the subtleties of the instruments.

64 Audio U18s

“Peace of Mind” by Avicii demonstrates the U18s’ ability to deliver both the tight punch and deep rumble in the bass of EDM and pop. The bass extension is well constructed giving an immense power to the dynamic shifts of the bass drop. The U18s is able to deliver the layering between walls of synth, up-close personal vocals, and deep powerful bass without losing the clarity or detail in any one of the layers.

The violent drum attack at the start of Rush’s “One Little Victory” is captured in all of its intensity and emotion by the U18s. Alex Lifeson’s guitars sound like they’re coming out of amps ten feet high flanking the listener on both sides. Geddy Lee’s bass and vocals are coming at you head on like a wailing banshee on top of a Mack truck. The U18s is the perfect tool to capture, the immensity of the performance, alongside the nuance and emotion of the performers.

Taking a step back from searing guitars, pounding drums, and bass that hits like a truck, the U18s is also capable of delivering the delicate intricacies of a masterful solo piano performance like Alexandre Kantorow performing Brahms, Bartok, and Liszt. Throughout the performance from the nimble staccato introduction of “Scherzo, Allegro - Trio, Poco piu moderato” to the softer moments of “Andante con expression” the U18s captures the dynamics from pianissimo to fortissimo, and provides a natural, musical timbre to the piano, and a dynamic energy to the performance.

Apex Modules: How big of a difference do they make?

The U18s includes three Apex modules, the mX, m15, and m20, which enable you to tune aspects of the sound to your liking – or to increase sound isolation if you’re in an environment where you want to stop noise bleed one way or the other. There are subtle but clearly noticeable differences between each one. The mX provides the least isolation, and with that comes a small expansion to the soundstage and a greater sense of openness in the highs, but at the cost of a little bit of bass impact. The m15 was what I spent most of my time with, and what felt like the U18s was primarily tuned to sound like, with an overall balanced sound. The m20 provides maximum isolation, which narrows the soundstage a bit, but also turns the bass impact up a couple notches. For the most reference-like tuning, the mX is likely your best bet, while the m20 is a bit more fun, and edges the U18s closer to basshead territory.

Comparison: Noble Sultan, Empire Ears Odin

In terms of tuning and general capabilities, there are a lot of similarities between the Sultan, Odin, and U18s, but also some clear differences. The Sultan and Odin are very similar from a technical and tuning standpoint, while the U18s lacks both the electrostatic and dynamic drivers which give Odin and Sultan some of their character. From a looks perspective the U18s is also the most reserved, with a more simple gray and black design, up against the Odin, which evokes the Bifrost of Norse mythology, and the somewhat more staid, but still elegant pearloid faceplate of the Sultan.

64 Audio U18s Noble Sultan

In terms of sound, the Odin and Sultan both have a more forceful, prominent bass presence, with the U18s providing ample impact that’s impressive for a balanced armature array, but it’s just not on the same level as the dynamic drivers in Odin and Sultan. Despite Odin having more drivers dedicated to the low-end, Sultan’s bass still feels a bit stronger by comparison. The m20 module closes the gap between the U18s and Odin a bit, but doesn’t quite get it all the way there. In the midrange, the U18s really shines, with its layering that provides a great sense of separation between instruments, but also a strong sense of cohesion in the overall sound. In the treble, the Odin is the most prominent – sometimes maybe a little too prominent – with the Sultan and U18s sharing a similar treble response. Both have a strong treble presence, but with a smoother character.

The imaging and soundstage are where the Odin and U18s seem to leave Sultan behind a little bit. While all three present large realistic soundstages with excellent imaging, the Odin And U18s just feel that much more holographic and immersive. While all three have strong characteristics, and I could spend all day going back and forth between them, the big standout aspect of the U18s is the combination of incredible layering which simultaneously provides blending and separation in a highly immersive fashion, and the way it presents those layers in a holographic 3D image.

The Bottom Line

The U18s is an incredible IEM which bends its studio reference nature just a little bit to create an engaging audiophile sound. Nothing is exaggerated, everything is in balance, and the realistic immersive space it creates helps transport you into the music.