64 Audio tia Fourté Universal IEM Review: Room for detail

64 Audio tia Fourté Universal IEM Review: Room for detail

Review written by Andrew Park (@Resolve)

Review unit provided on loan for evaluation by headphones.com

For another perspective, check out Ian Dunmore's (@Torq) review of the 64 Audio Tia Fourte.


It's no secret that I'm a big fan of 64 Audio's U12T and tia Trio universal IEMs, enough that I would put them both near the top of my list for best IEMs so far. Both of these IEMs have been able to redefine for me what's possible with this type of device, and not just as far as technical ability goes. 64 Audio also deserves praise for their attention to tonality, as they've been able to achieve better tonal balance with the offerings I've heard so far than just about any other IEM I've yet come across. Naturally I've been looking forward to evaluating their flagship the tia Fourte. It's now a question of whether or not it lives up to its price tag.


  • Driver Type/Count - 3 precision BA drivers, 1 dynamic driver
  • Driver Configuration - 1 tia high, 1 high-mid, 1 tia mid, 1 dynamic low
  • Sensitivity - 114db @1kHZ @1mw
  • Impedance - 10 Ω @ 1kHz
  • Crossover - Integrated 4-way passive crossover
  • Isolation - 20dB internal apex technology
  • Price - $3600


    In the box

    • Fourté Universal In-Ear Monitors
    • 64 Audio Personalized Protective Case
    • Cleaning Tool
    • Shirt Clip
    • TrueFidelity Eartips (S,M,L)
    • Silicone Eartips (S,M,L)
    • 48" Detachable Premium Cable
    • Round Sticker
    • Product Manual

      Build, Design & Comfort

      Just like with their other designs, 64 Audio have nailed the physical aspects of this IEM, as it walks the line between understated and aesthetically interesting. The tia Fourte has the same 'two-piece' style for the shell housing, with the top section revealing a logo inlay surrounded by an orange/brass colored trim. I can appreciate and aesthetic that goes for a "purpose built" but still looks good kind of thing. As a result, the tia Fourte also feels solid and rugged - not something I'd worry too much about damaging. But at the same time, this is an extremely expensive IEM, so I'd always recommend using the included case. The case is unfortunately more cumbersome than I would have liked for normal use, but it's important to recognize that an IEM like this is also meant for musicians and audiophiles, and not exactly a casual "on-the-go" type of device.

      For comfort, I have no problems getting a good fit. While maybe not quite as comfortable as something like the Legend X, the medium-sized tia Fourte has a common shape that anyone who has used 64 Audio IEMs in the past will be familiar with.

      Score - 9/10


      As the name suggests, the tia Fourte is a four driver IEM (3 balanced armature and 1 dynamic driver). I was originally impressed with the U12T's detail capability, especially where they implemented their 'tia' BA driver for upper frequencies. Well with the tia Fourte, 64 Audio have implemented two of their 'tia' drivers, one for the upper treble and one for the mids, which will become important later on in this review. But at the moment, this configuration has yielded even better technical performance than I imagined was possible after hearing the U12T, tia Trio, and even the Empire Ears Legend X. In fact, the closest for technical performance I can think of right now is the Legend X, albeit with a very different tonality.

      Detail Retrieval

      For detail retrieval, this is possibly one of the most impressive IEMs I've ever heard. It gets top marks here for representation of textural qualities, structural definition for images, and image distinction. Something I keep noticing is textural qualities throughout the midrange, and my guess is this has to do with the tia BA driver here. This is also brought forward a bit by the Fourte's tonality, which we'll discuss. But for what I like to call 'internal detail retrieval' - the quality that lets you peer into the music better - the tia Fourte is spectacular. The only reason I'm not giving it 10/10 is likely more to do with tonality than anything else.

      Score - 9.5/10

      Speed & Dynamics

      The Fourte performs similarly to the Trio in this regard (the Trio has 2 balanced armature drivers and one dynamic driver for bass frequencies). While not quite as tight or snappy sounding as the U12T in the bass, the Fourte's dynamic driver makes up for it in terms of slam and impact, and from memory, I find it a bit tighter than the Trio, but once again that could come down to tonality. I think this is a tradeoff most would be okay with. The U12T redefined what was possible for bass frequencies with BA drivers, at least for me, but I think I'd still prefer the DD hybrid design going on in the Trio and the Fourte - at least for bass frequencies.

      Score - 9/10

      Stage & Imaging

      To my ear, this is the Fourte's biggest strength. While I really liked the Trio, I did find it to be somewhat held back by its stage. Not that it was bad, just that it wasn't as spacious as the Legend X by comparison. Well, I can confidently say that the Fourte is at least as good as the Legend X in that regard. In fact, I'd go as far as to say this is the best stage for any IEM I've yet heard - and I think in some ways this is the main point of the Fourte. It's likely that having a wider range of frequencies handled by 64 Audio's 'tubeless' tia driver helps with this as well. The other important consideration for the Fourte's soundstage is its frequency response, as there is an upper midrange recession around 3-4khz that the Trio doesn't have. And this does also add an improved 'sense' of stage, as is common with many headphones that do this.

      Imaging and image precision is also superb, once again better than what I found with the Trio and U12T. This was most noticeable during busy passages in music with a lot going on. For these recordings, it's common for image precision on lesser headphones to fall apart a bit and muddle things together, and for the Fourte that doesn't happen - even when actively playing music that's meant to test it to its limits.

      Score - 9.5/10


      Even though the Fourte makes use of 3 BA drivers, I don't notice much of the dreaded 'BA timbre'. For those unaware, this can be described as a kind of metallic smearing effect that, in the worst cases, obscures details. I'm again led to believe that the Fourte gets away without this effect being bothersome because not all BA drivers are created equally. Comparing the Fourte directly to the Drop X Zeus 14, which uses Knowles BA drivers, it's clear that 64 Audio's tia driver doesn't have the same limitations when it comes to timbre. I did find I could hear it slightly on both the tia Trio and the U12T (the latter being entirely comprised of BA drivers), and while it wasn't intrusive or annoying on those, I wasn't once distracted by it on the Fourte. This may also have to do with the fact that an additional driver means that each individual driver isn't being asked to cover as wide a frequency range - especially with the use of that tia driver for the mids.

      Score - 9/10


      Here's where things get a bit weird. Ever since becoming acquainted with 64 Audio IEMs, I've come to learn that these guys are extremely meticulous about getting the frequency response right. So it's not just about technical performance. Everything I've heard so far sounds calculated and well thought out. I think the same is true for the tia Fourte. However, the Fourte's tonality may be more appropriate for musicians looking for a very specific type of sound than the traditional audiophile's desire for 'neutral'. 

      The overall tonality is more of a 'W' shape to my ear. And this is likely again where the use of that extra tia driver for the mids shows up. So you get a bit of a bass and treble emphasis, with a midrange bump and upper midrange recession to simulate an increased stage.

      To me, this sounds like music is being played in a very specific room. This is again why I think the Fourte's tonality is also well-calculated, just like the rest, even if it's not as typical. 64 Audio have managed to produce an IEM that doesn't suffer the pitfalls of wonky tunings by unnecessary peaks or dips in problem areas (like 8khz), and yet still ended up with a somewhat non-traditional sound. I do think this is done tastefully, as the deviation from typical neutrality is minor, however for some this won't be the classically 'audiophile' tuning that many of us have come to enjoy - and I count myself among those who prefer the U12T's tuning as well.

      With that said, there aren't any noticeable problems either. There are no sibilant peaks or percussion compression issues to deal with, although I do find it to have just a bit too much energy around 5-6khz for my taste. I'm reminded a bit of the HiFiMAN Arya's treble in that regard as well, where it's not exactly fatiguing or unpleasant, but for certain recordings it walks the line a bit. Thankfully, the overall frequency response retains decent tonal balance for instrument representation. The rest of the treble is well-extended and resolving, even more-so than on the tia Trio, and it's not overdone to the point of over-emphasizing anything unnecessarily.

      And so that's why I think the Fourte may be more well-suited to the audio pro or musician looking to simulate a specific type of room. Not only do you get the stage benefits from a dip around 3-4khz, you also get something that sounds like a room you might be playing/recording in. Now that's not to say that this is a better tuning than the U12T for musicians either, just that I can see this being a calculated choice for certain applications.

      I have to think that if 64 Audio were able to produce something with the technical performance of the tia Fourte, and the tonality of the U12T, they'd simply win the IEM game - but of course, that's easier said than done. For my part, I do wish that the Fourte had been a more familiar tuning, even if I can completely understand the reasons why this is what they went for.

      The bottom line for tonality, in my opinion, is that while it's not ideal for those of us looking for a turbo U12T, you can very clearly see the same meticulous and calculated approach to tuning an IEM that I think 64 Audio should still be known for here.

      Score 7.5/10


       64 Audio U12T

      The tia Fourte has a more 'colored' tonality, while the U12T is a more traditionally audiophile sound to it. The Fourte has better technical performance, with more realistic textural representation throughout the mids and treble. Bass is tighter on the U12T, but there's more punch and slam on the Fourte. Stage is also better on the Fourte, along with even less noticeable BA timbre (although the U12T is good in that regard as well).

      64 Audio tia Trio

      The only thing holding the tia Trio back in my opinion (if at all) is its slightly smaller soundstage. The Fourte solves that, but at the cost of a slightly more uneven sound. Remember that the tia Trio is also a bit 'V' shaped, with a bit more bass elevation, and so in that sense the Fourte is perhaps a little bit more analytic with the midrange bump as well. But the upper midrange recession isn't there on the Trio. I think between these two, it's very clear that the Fourte has better technical performance as far as detail and stage goes, but the Trio's tonality may be preferable to some. Also, from memory, the Trio slams a bit harder - but once again that's likely just because there's more bass energy there.

      Empire Ears Legend X

      The Legend X has a much more bass emphasized tonality, and fits squarely in the 'fun' category. But its technical performance is up there with some of the best, especially its holographic stage. For technicalities alone, I'd give a slight edge to the Fourte, but it's very close. The bigger difference has to do with the tonality. In spite of the Fourte's excellent bass response, if you want slam and bass energy, there's really not much else out there like the Legend X with its two W9 dynamic drivers handling lower frequencies. But for something a bit more analytic, the Fourte is the better choice. Personally I liked the Fourte more, but I could see someone preferring the Legend X for that 'fun' sound.


      The 64 Audio tia Fourte is a somewhat strange and yet simultaneously excellent IEM. You get top tier technical performance, coupled with an excellent soundstage, and a tonality that emphasizes the sense of space. In many ways I consider 64 Audio IEMs to be tools, or devices intended for musicians or the pro audio crowd to use critically in their work. And while the Fourte strays a bit from the more familiar U12T in its tonality, I can see the Fourte being chosen by anyone looking to simulate a specific type of room, and to get that extra sense of stage it provides. For the rest of us Audiophiles, I think this tonality may be a bit more of an acquired taste, but that's not without being worthy of praise as well. With the tia Fourte, we have a somewhat unique flavor of 64 Audio's tuning prowess that puts a spotlight directly on its technical achievements. I may personally still prefer the U12T's tuning overall, but the detail and stage benefits of the Fourte are difficult to overlook. To many, I think it will be impressive enough to make it worth considering getting into this kind of tuning.

      Score: 8.9/10

      Check out the video review here:

      -Andrew Park (@Resolve)


      Join the discussion about the 64 Audio tia Fourté at "The HEADPHONE Community".


      Buy the 64 Audio tia Fourté on Headphones.com here at the best price available.

      Support more content like this by shopping on Headphones.com

      Banner Ad with the Headphones.com logo and text: The Best Place to Buy Headphones and Home Audio on the Whole Internet. 365 day returns, Free shipping over $100, Insanely good customer service.
      Back to blog