Before we begin this review, I want to start with a disclaimer: I am not an audiophile. While these earphones are most certainly pointed at audiophiles and those with far more expendable cash than I have, I’m going to bring you my thoughts as a someone who absolutely loves music, but also suffers from tinnitus and cannot pick up on the little things that most audio reviewers rave about.

All of that being said, I think this review will come across far more useful for the common users interested in a very high-class pair of earphones.

If you really want to boil down the Ultimate Ears 18+ CSX, you could easily say they’re a $1,500 pair of Bluetooth earphones. That’s a massive oversimplification, of course, but you wouldn’t be wrong either.

Backing up a bit, Ultimate Ears (UE) is one of the leading companies in high-end audio today. The company has been around for a few decades and was recently acquired by Logitech. Its history of audio excellence, however, extends back to the early days of Custom In-Ear Monitors (ciems).

Ciems are earphones that are custom molded to your ear and provide a flat, real representation of what you’re listening to, rather than exaggerated EQs that make music almost unrecognizable.

Ciems are not cheap, though you can find far more inexpensive products than the $1,500 18+ CSX. The question is, do you get what you pay for? In a word, yes. The 18+ CSX are the most enjoyable audio experience I have had in the years that I’ve been reviewing audio products. Let me tell you why.

Custom Molding


First off, we’re going to start with the “C” in ciems. The UE 18+ CSX are custom molded to your ear canals through a “Fitkit” that the company sends when you order your earphones. The package arrives, you go through the molding process and send it back to the company. Within a few weeks, you have your earphones.

The process is quick and, for me, was generally painless. In the Fitkit, you get two sets of molds (small and large), a mirror, and a power adapter.

Why the power adapter? Well, the mold you place in your ear is actually going to heat up so it can form to the shape of your ear canal. It doesn’t get too hot, but it does get warm enough to produce an interesting sensation. Once it’s done, it cools down and you now have a custom mold of your ear!

The process is guided by an app that you can download for either Android or iOS. I had trouble with the Android app so I used my wife’s iPhone and it worked like a charm. The entire process only took about 20 minutes and I was ready to send the molds off to UE for them to construct my IEMs.

Mine took about ten days to get to me after I sent the Fitkit back to UE, which I think is an appropriate turnaround for a high-quality product like this. When you’re dropping this kind of cash, you want it to be perfect the first time.


If you’ve never experienced Custom In-Ear Monitors, there’s not a fantastic comparison out there to convey exactly what they feel like. I suppose they’re like a pair of gloves that hold tight to your hands, but don’t restrict your movement.

While other earphones may extend further into the ear canal, the UE 18+ CSX are only moderately deep. This is great for comfort and sound quality, but there were times when I did feel like I could shake them out of my ears.

If you’re looking for something to take to the gym for an intense workout, you may want to consider a different product or a third party clip to make sure they don’t go flying. During my relaxed exercise, they were perfectly fine.

If you have sensitive ears, you may get some fatigue during long listening sessions. I think most people will be fine because I am one of those people with sensitive ears and it took three to four hours of continuous listening before I felt anything remotely close to that.

An underappreciated but important-to-me feature about these earphones is that they’re basically flush with my ears. Why would that be important? I love listening to music when I’m laying down. It helps me drift off to sleep and I often read laying on my side with music on. There was no extra pressure on my ears because of the size and shape of the UE 18+ CSX which was an unexpected but wonderful surprise.


Remember when I said calling these $1,500 Bluetooth earphones was a massive oversimplification? Well, it definitely is. They’re definitely not just Bluetooth earphones because they’re wired too.

The UE 18+ CSX come with a braided 48-inch cable that quickly snaps into place to provide a 3.5 headphone jack plug for your phones that still have a headphone jack. And, yeah, I guess computers, amps and other things that you can plug one of those things into. But, we all listen to music on our phones now right?

Unfortunately, the braided cable doesn’t include any inline controls, but it is one of the better cables I’ve come across. It’s very workable and never sticks to a shape, which can be pretty annoying with wires. It’s long enough to reach down into my pocket when plugged into my phone or into my computer when I’m at my desk. Is it the best? No. But, it does the job. You can make the case that if you’re dropping this much money you want something more than “just does the job” and that’d be pretty fair.

As for Bluetooth connectivity, there’s an entirely separate wire you plug in for that. It connects to the buds and goes behind your neck like many other Bluetooth earphones out there. It does include an inline control unit that has three buttons and a battery that should get you about four hours of playback from our testing. A battery unit that charges via micro USB attaches via pogo pins to recharge the unit.

The battery gives you an additional charge (so about eight hours total) and can be used either as just a battery or while it’s charging as well. More than once I’ve attached the battery unit to the 18+ CSX and left the house. You can also throw it in your pocket and just charge up when you need. Then, when you get home, throw the battery on the charger or the whole unit. It’s pretty flexible, which I really enjoy.


All that’s great, but how do they sound?

The first thing you need to keep in mind about In-Ear Monitors are that they’re monitors. Monitors are supposed to give the truest representation of the music you’re listening to without introducing artificial EQ. If you want booming, overemphasized bass, there are other products that will make you much happier. If you want to listen to your music the way the artist intended, you’re on the right path.

I have a hard time really explaining the joy that listening to music with these earphones really brings me. I’ve dabbled with some high-end audio products but mostly stay in the shallow end with the Apple Airpods Pro and Sony wh-1000xm3‘s of the world. These are expensive products, but they don’t touch the UE 18+ CSXs.

I can only describe the sound stage as broad and wide. You truly have a more natural sense of what the music is supposed to sound like. These don’t invent bass or treble that wasn’t supposed to be there in the first place which makes vocals sound absolutely brilliant. Bass still booms, but its because it’s supposed to boom. Clear instrument separation is a joy and you’ll definitely pick up details in your favorite songs you’ve been missing all these years.

There’s no active noise cancellation here, but you really don’t need it. Noise cancellation introduces artifacts through the process of filtering out sound and can negatively affect the audio or give a sense of your head being in a vacuum. The seal in your ears due to the custom molding provides the same noise-cancellation results without any of the negative aspects of ANC.

If you’re not terribly impressed with how your earphones sound or you just want to tinker, the UE Custom app has an advanced EQ that will let you dial your sound signature exactly where you want it.

You can save custom profiles, but these profiles will only work in Bluetooth mode, unfortunately. We’d love to see UE expand the option to work in wired mode here, but you’re stuck with Android’s EQ settings for now.


It’s not hard to say you absolutely get what you pay for here. If you’re slotting these on scale with the $10 earbuds you can get that the corner store and these near the top, you will get diminishing returns once you pass that $300 price but that’s not to say there aren’t value in the UE 18+ CSX.

Most people are going to be fine with Airpods; that’s largely why Apple has been so successful with them. We’ve profiled a ton of audio products here on AndroidGuys that will do the job just fine. But, if you’re looking to up your game, these are an excellent place to start.

I really love how these sound, and I know that’s a rather bland statement, but it’s true to the feeling. It’s easy to exaggerate when reviewing products, but the word “love” is accurate here. Accurate, much like how these sound. No booming bass that rattles my head for no reason, no cymbals piercing through the vocals to ruin the moment. Just clear, clean, warm music at all times. Wired or wireless.

Indeed, $1,500 is a lot of money, and I’m not suggesting everyone run out and buy these. If you’re serious about audio, I think you start your search here and branch out. UE is incredibly successful in the audio game because their products are simply among the best. The UE 18+ CSX are a prime example of the quality of the company and I fully recommend them if you have the money to spare.

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