64 Audio U4SE

On a “budget” and still sounds great!

PROS: nice bass impact, balanced tuning, great retrieval of details, original shell design compatible with both apex/adel modules, custom storage case.

CONS: more eartips wouldn’t hurt.

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.

Manufacturer website: 64audio.


Feel free to call me spoiled, but it’s not easy to go back to the “lower end” IEMs after being exposed to different flagships. A lot of work goes into the design and the development of flagship models where manufacturers are trying to set the new high bar. Though, sometimes stepping down in driver count of lower model doesn’t necessary mean a water-down design but rather a different signature with some performance compromises. For example, when I reviewed U12, my readers asked me about U6 which many consider to be a scaled down version of U12. Not everybody can afford the flagship, thus a lower driver count model could be a nice alternative. Similarly, U8 is known for its powerful bass impact which you can still get in a scaled down and more affordable U4 version.

Actually, the fascination with bass impact has been slowly spreading across audiophile community, and I’m sure 64audio received a lot of feedback about it. As a result, they came out with a Special Edition U4SE model, retuned to give the new audiophile flavor to an old basshead classic. When I received U4SE, the original intent was to take a listen, provide feedback, and maybe write a short impression, but a few paragraphs I started with turned into a full review. I actually learned this Special Edition version laid down some ground work for 64audio U18/Fourte flagships. Despite U4 four-driver arrangement, it shares a similar setup as the mid-high drivers in 64audio current TIA flagships, including how Apex bore blends with the sound at the back of the stem, resulting in Apex module being even closer to the speaker while relieving the air pressure and fine-tuning the sound.

Of course, you have to be realistic, no manufacturer is going to create a giant-killer lower-end model to compete and to challenge their own flagships, but 64audio certainly did create a Special Edition model at a more affordable price (relative to their other higher end models) and with a very impressive sound performance I would like to discuss here in my review.


The unboxing experience of U4SE is common with other 64audio A/U models, from 2 to 12 driver ones. The packaging box itself is very compact – a dead giveaway that you are dealing with a custom case and not a typical Pelican case. The cover of the packaging sleeve features a company logo with a picture of monitors corresponding to either Universal or Custom shell design. With an outer sleeve off, you will see a cover flap with a picture of a performer and “hear everything” printed underneath, very appropriate for this Special Edition model since it has great retrieval of details. Once you lift the cover flap up, on the other side of it you will find a Quick Start Guide with info about headphone listening safety, volume advisory, and pointers about putting these monitors in your ears – all useful info, especially for beginners.

Also, inside you will find a custom travel case, 64audio stickers, and a plastic bag with eartips. Overall, a very compact packaging, unlike U18/Fourte which intentionally had a large packaging box with enough room to list all the special design features of those latest 64audio flagships.


Since this is a universal version, it arrived with a handful of eartips. Here you will find a genuine Comply set with 3 pairs (S/M/L) of foam eartips, and a pair of double-flange silicone tips. Choosing the right eartip is a matter of a personal preference which going to affect not only the fit and the comfort, but also the sound. As I mentioned in all of my previous 64audio reviews, I usually don’t find the included tips to work well with my ears, and I end up using a pair from my private stash. I do wish 64audio would include a better selection of eartips, maybe another set with hybrid tips that have a firmer cap and a longer stem.

Other included accessories were a custom storage case which I’m going to talk about next, and 64audio round stickers. Inside the storage case you will find a small dehumidifier, cleaning tool, and a shirt clip.

The storage case.

In all of my previous 64audio reviews, I called their new case a “VIP case”. Everything from an easy to handle wide latch and air valve eliminating build-up of inner case pressure when you close it, to individual earpiece storage sections with a removable rubber lining and a custom built-in cable winder, a spot to plug right angled headphone connector and to place the included round dehumidifier container, as well as a built in organizer to hold securely a shirt clip (included), a cleaning tool (included), and 2 sets of APEX modules (M20 included) – all this was custom tailored and well thought of. There is even enough room if you decide to use a thicker replacement cable.

When you place the order, you can also specify if you want your name to be etched on the top of the storage box to personalize it. While many companies use off-the-shelf Pelican or Otterbox storage cases with a pre-cut foam inserts, 64audio went one step further with their own custom designed case which protects your investment and keeps everything organized inside. It also great to know that regardless of 64audio model, 2 driver or 18 drivers, you are still getting this custom storage case with every order.


While U18/Fourte flagship now feature 64audio new SPL cable, U2-U12 models still come bundled with their original OFC cable, but it’s an updated version which has a more durable 2pin connector housing and a softer cable sleeve.

As far as the cable goes, it feels durable and still flexible without springy memory effect. It has 4 separate conductors, braided from the connector to y-splitter, a tight rubbery black shielding, and no microphonics effect. The headphones plug is a right-angled 3.5mm TRS gold plated connector. The y-splitter is a common heat-shrink tube, nothing fancy, and the chin-slider is a clear short tube piece with enough friction to keep it from sliding freely. After the y-splitter, cables are twisted, and toward the earpiece connector have a memory wire which you pre-shape for comfort. I’m not a big fan of memory wires, but this one works fine, keeping the fit secure. The 2pin connector is universal which can be used in both surface and recessed 2pin shell sockets, and it’s conveniently color-coded with a Red dot for the Right side and a Blue dot for the Left side which you have to make sure to attach with both dots pointing the same way to avoid phasing effect.

Aftermarket cables.

Though I have tried different aftermarket cables with U4SE, I ended up coming back to the original OFC because U4SE tuning has a little peak around 9k, and most of the SPC, Silver, Copper, and other exotic cables seems to add a little more brightness and air to the treble, making the sound a little piercing to my ears. With OFC cable, you still get a well defined bass, but upper mids and treble have a bit smoother tonality, just enough to take an edge off the treble. This is a purely subjective opinion because I’m sensitive to high frequencies. But feel free to experiment with other cables if you want to push the retrieval of details and the resolution further.

Out of the box, I actually preferred 64audio new SPC cable, but after 24 hours of burn in, I reverted back to the original OFC cable. I know some people don’t believe in burn in, even with dynamic drivers, but I’m describing what I hear. You have to take into consideration that crossover components and solder joints can go through a very small change which could have a subtle effect on FR, just enough to be noticed.


U4SE Special Edition comes only in universal-fit design, using hypoallergenic acrylic shells in translucent charcoal color. I will talk more about modules later, but the model I received has the original 1st gen shell design that fits Adel modules which also fits Apex modules, with M20 Apex module included by default. Inside this very compact shell, you have 4 balanced armature drivers, which include 2 low, 1 mid, 1 high, and a large vent cavity to accommodate either Apex or Adel modules. With this 3-way partitioning, you also have a corresponding 3-way passive crossover.

Unlike the original 4-bore U4 design (one bore per each driver group and Apex module), here you have a new 2 bore design with 2 visible sound tubes. As I mentioned in my Intro, U4SE shares a similar setup as the mid-high drivers in TIA flagships, also sharing how Apex bore blends with the sound at the back of the stem. I don’t know this for a fact, but it would make sense to me if one sound tube has connection to low drives, while the other one is associated with Apex and mid/high drivers. Of course, both U18 and TIA Fourte flagships are based on tubeless design, using sound chambers to blend the sound.

The shell itself is compact, doesn’t stick out of my ears too much, though don’t expect to put your head with your ear down on the pillow while wearing U4SE. You also get access to easy removal and replacement of Apex module, and my favorite – long enough nozzle for a comfortable fit, depending on the eartip selection. The nozzle has a thicker part in the middle which keeps eartips from sliding off when removing the shell from your ears. The faceplate is flat and comes with a default 64audio logo print. The inner part of the shell has rounded edges and sits comfortably inside the ear. The overall size of the shell is on par with U6, maybe even a touch smaller.

The fit.


Page 2: Sound analysis, Pair up, Comparison, and Conclusion.

6 thoughts on “64 Audio U4SE

    1. I never heard the original u4, but others mentioned it has a rather basshead oriented tuning – more emphasis on low end and rolled off upper frequencies. Again, never heard these so can’t say for sure, but sounds like a different tuning in comparison to SE version.


  1. My question is not directly related to U4SE. I saw you mentioned UM Pro 50. Can you please briefly compare UM Pro 50 to iBasso IT03? Are they similar or completely different in sound signature? I own UM Pro 50 (upgraded from UM3X) and planning to get iBasso DX200 soon. What, in your opinion, would be a step up from UM Pro 50 to pair with iBasso DX200, considering that I like UM Pro 50 signature? Thank you!


    1. Something like it03 or u4se will be a side grade rather than upgrade from umpro50. Westone has this unique signature where the sound is less aggressive, more laid back. Going to it03 will make sound more v-shaped, where stepping up to u4se will be an upgrade from it03. U6 has a similar less aggressive tonality, but going from umpro50 to u6 will mean sacrificing bass and smoothing out top end. Look into mine w80 review, in my comparison between w60, w80,es60, umpro50 – it can give you a good idea of how these Westone iems stack up against each other. Also, keep in mind, it04 is around the corner.


    1. I have been told it could go on sale toward the end of this week. This is a limited special edition. They don’t sell it regularly. Yeah, curious how it04 will sound as well.


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