64 Audio U12t Review

I have to admit, I slept on the 64 Audio U12t for quite some time. I had heard it briefly, and then also confused my recollection of it with its big brother, the tia Fourté. While it’s 12 driver design is certainly somewhat exciting, the U12t found itself eclipsed in my mind by the various hybrid and “tribrid” designs in its price range – most with flashier, more colorful shells. But when I finally sat down to spend some time with it, I was surprised and impressed at its performance.

Build and Design

The U12t has a very straightforward design. The shells don’t have the “wow” factor of many similarly priced IEMs, but, on the flipside, they’re very lightweight and comfortable. In addition to the IEMs and cable, the box includes a very solid case and a selection of silicone and foam eartips. While the design is subtle, the materials are premium. The shell itself is a single machined piece of solid aluminum, creating a solid, durable IEM. The cable on the other hand, is a little bit lacking: it’s tangle prone, and feels a bit too flimsy to be paired with IEMs of the caliber of the U12t.

64 Audio U12t

One unique feature that 64 Audio uses is the swappable “Apex” modules. The U12t comes with 64 Audio’s m15 and m20 Apex modules, which allow you to adjust the balance between sound isolation and the attenuation of bass frequencies. Basically, the larger vents in the m15 module provide improved bass response, but slightly less isolation, while the smaller vents in the m20 module provide near complete isolation at the cost of a reduction in bass response.

The Sound

With 12 balanced armature drivers, the U12t is a highly technical IEM which provides incredible detail and a strong sense of space and imaging. The driver composition, with 1 tíaTM high, 1 mid high, 6 mid, and 4 bass drivers with a 4-way passive crossover, might lead you to believe that the U12t is going to be mid forward, but instead it has more of a “v” tuning with small accentuations in the bass and treble, and some recession in the midrange. In fact, while it certainly isn’t a basshead IEM, the 64 Audio U12t has some of the most physical, impactful bass I’ve ever heard out of balanced armature drivers.

Listening to Marvin Gaye’s “What’s Going On” the vocals are clear, forward, and personal. The drums and percussion have a nice feeling of space. The imaging places the drum kit just off-center to the right, while the percussion section flanks the drums to the left. The bass carries the smooth groove along with a clear delivery of each note, free of muddiness or congestion. The U12t gives you so much detail that you can get lost in the song – whether you’re listening to the interplay between the percussion and drums, the counterpoint and harmony of the backup singers, or the subtle accents of the keys and guitars – I found myself getting so caught up in the small details that the song was over before I knew what happened and I had to restart it to listen again.

64 Audio U12t Chord Hugo 2

While it is a highly technical IEM, the U12t also sounds very natural with acoustic instruments. Dave Matthews “Two Step” provides an incredible complex soundscape for the U12t to paint. There’s the tight attack and crisp roll-offs of the cymbals, the saxophone accents weaving in and out of the chorus, the plucked pizzicato strings of the violin, and the intense stereo split of the guitar. The whole song is almost an exercise in sensory overload as the band plays complex parts which weave in and out of each other and the U12t provides detail, clarity, and excellent  separation between the parts. At the same time, each instrument sounds clear and natural, while the overall interaction is pleasant and musical, rather than just being technically excellent.

In an attempt to really stretch the U12t’s abilities, I put on some tracks by Viking Metal band Tyr. I was blown away by how powerful and visceral the sound was. Not only was every note of every blazing fast guitar run perfectly clear, the drums hit hard, and drum fills stretched across the huge soundstage, feeling like they were coming across an impossibly sized row of toms. The vocals gave the impression that perhaps I had gotten closer to an angry Viking warrior than might be beneficial for my continued health. Thankfully I was not actually having a run in with a raging Norseman, but instead was just experiencing the genuinely holographic imaging of the U12t.

On Steven Wilson’s “Perfect Life,” the introductory synthesizers swell in warm layers, and the bass and kick hit with both impact and clarity. The U12t delivers the ever-shifting layers of guitars and synth with incredible dynamics and emotional impact. When the vocals hit with the chorus, they’re clear and personal. As harmonies and layers of instruments are added, the song builds to its emotional climax, and the U12t unpacks each intricate detail for your ears across its massive soundstage.

64 Audio U12t Astell&Kern SE200

I did a bit of testing using the Apex modules, and found that they generally work as advertised. The m15 provided what I would think of as the “standard” U12t sound, and provided what I would consider a normal amount of isolation for an IEM. The m20 provided a clearly higher degree of isolation from outside noises (tested by playing YouTube videos loudly off my phone while listening to music via my laptop), but clearly impacted the bass response of the U12t and shrunk the soundstage a little bit. It’s interesting, the bass with the m20 initially felt like there was a little more tightness and physical impact, but in the balance between bass and treble, the treble quickly overpowered the bass. If you need the absolute maximum possible sound isolation, or if you feel like you’d like a little bit less bass, the m20 is a good option, but I’d recommend the m15 for most listening circumstances.

The Astell&Kern SE200 and Chord Audio Hugo 2 were the primary devices I used for testing. I found both to interact with the U12t in a similar fashion, and provide a clear neutral canvas for the U12t to work with. I also tested using my iBasso DX160 which I’ve configured to provide a slightly warmer sound profile, and that also proved to be an excellent pairing. One aspect of the U12t to note is that the bass was very seal dependent, and if you’re not using a pair of well fitted eartips, the U12t might come off as a bit bright.

The Bottom Line

The U12t is an IEM that might easily fly under your radar. There’s nothing flashy about the look or design, but it’s all impeccably executed: a simple shell that is durable and functional, and a driver complement that delivers sweet, smooth highs and powerful, physical lows with everything in between. The U12t is an incredible execution of balanced armature technology and an absolutely top tier IEM.