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Ultimate Ears Pro Reference Monitor In-Ear Headphones Review

By Smit Patel


  • Product Name: Reference Monitors
  • Manufacturer: Ultimate Ears Pro
  • Review Date: August 16, 2015 08:00
  • MSRP: $999
  • First Impression: Pretty Cool
  • Input sensitivity: 112 dB @ 1 kHz, 1mW
  • Frequency response: 5 Hz – 22 kHz
  • Noise Isolation: -26 decibels of ambient stage noise
  • Impedance: 35 Ohms@ 1 kHz
  • Internal speaker configuration: 3 proprietary balanced armatures with multiple passive crossover points and dual bore sound channels
  • Input connector: 1/8” headphone jack; compatible with all systems
  • Warranty: 1-year

With their headquarters based in Sunny-Side California, Ultimate Ears was initially founded in 1995 by Jerry and Mindy Harvey. Their headphone became so popular that within just a few years of UE’s induction, “The Rolling Stones”, Enrique Iglesias and Faith Hill were loyal customers. A decade later, the company was acquired by Swiss electronic giant Logitech. Though an initially controversial move, the vice president of headphones, Phillipe Depallens, claimed that even with Jerry Harvey’s departure they still produce some of the best in-ear monitors the market has ever seen.

Like any self-respecting company, Ultimate Ears have not been afraid of venturing out and recruiting the help of other companies to progress themselves. This was evident within the early stages of the company’s collaboration with Westone to produce shell casings to accommodate UE’s own internal circuitries. More recently, Ultimate Ears have contracted world-renowned recording legend Capital Studios to help craft the ultimate portable monitoring experience. The plan was to create a pair of Custom IEMs capable of technical accuracy and reproducing true to life music.

The finalised product branded the “Ultimate Ears Reference Monitors” was set to release and unbeknownst to UE would create a legion of highly devoted music professionals and audiophiles alike. The Ultimate Ears Reference Monitors (UERM) incorporates a three-way crossover, three driver design which can be considered a low number for its $999 price point. However, we should know all too well by now that quantity does not equate to better performance, nor does it dictate more deserved recognition. The Shure SE846 is a prime example of just that; an earphone which employs a quad-armature design yet renders an appreciably outstanding sound. With both companies refraining from the arms race to pack as many drivers as possible to appease the “more is better” attitude, an intelligent approach is taken instead. One that focuses on quality and emphasis on driver design as opposed to sheer quantity.  

The Custom In-Ear Process

As this was my first venture into custom in-ear monitors, the process was originally alien to me but it soon became clear how it all worked. Firstly, an appointment needs to be made with a person who carries out ear impressions (this is usually a qualified audiologist). Ultimate Ears pays for the ear impressions from a UE-endorsed audiologist as this is part of their all-expenses paid packaging. The whole process was not as scary as initially expected as there was absolutely no pain involved. A small sponge on a string is inserted past the second bend of the ear canal and a putty-like material injected from a syringe into the ear. The material is then allowed to set which takes around 5 to 10 minutes before the audiologist can remove both impressions and the string itself. The ear impressions are then sent to the UE’s lab in California where they are stored and shaped to make the final product.


What is incredibly interesting is that Ultimate Ears have revolutionised the custom-in ear manufacturing process through heavily investing in digital processes to improve productivity and precision. Whereas before, the silicone ear impressions were shaped by hand, the ear impressions are now scanned and stored on a computer. New software enables changes made to the ear impressions digitally which has numerous advantages. For one, the process is infinitely faster, and secondly, mistakes in the shaping process can be undone. The resulting ear mould is printed using a state of the art 3D printer worth just over $250,000. Consistency is key here and Ultimate Ears Pro are well aware of this which is why the price of digital manufacturing has represented a beneficial long-term investment. The statistics have even substantiated this with UE reporting over a 50% reduction in returns from poor custom in-ear fits and other such inconsistencies.

UE does not plan to stop there, but with the new invention of the digital laser ear scanner, they hope to make the process of obtaining ear impressions digitalised too. Instead of the normal putty material injected into the ear, a scanner obtains measurements of the inside of the ear and builds a virtual profile of an individual’s ear canal. The process again, is much more accurate than conventional methods, and in doing so saves Ultimate Ears Pro the costs of customers returning poor fitting monitors. The virtual impressions can be sent directly over to the UE labs in much the same way as the tangible ear impressions. The process saves time for not only the consumer, but also UE in the long run due to the lower return rates. At the moment, there are only a few places which do digital scanning but UE hopes to soon roll out the procedure to retail establishments across the U.S. as well as abroad.

What You Get: the Box & Accessories



Simplicity is adopted here and it certainly pays off. The monitors come in an Ultimate Ears branded carrying case which has your name laser-engraved below the “handcrafted for” text. Ultimate Ears Pro have even gone into the lengths of a “return for rewards” tag on the inside of the carrying case. Attention to detail like this is admirable and is a reason why this company has established itself loyal customers for their premium after sales support. The box itself is very minimalist and makes use of a luxurious felt-like lining to accommodate the case. Notable accessories include a 3.5 mm to 6.3mm gold-plated adapter and a cleaning tool. Maintenance of monitors is essential and the cleaning tool provides you with a means of cleaning ear wax from the monitors as well as removing debris from the outside of the sound bores. Without this type of cleaning, wax may accumulate on the inside of the sound bores affecting sound quality and even driver function. Thus, proper care should be administered when dealing with custom monitors to get the most use out of them.


Build quality & Design

As far as build quality is concerned, Ultimate Ears Pro has done an outstanding job in ensuring customers receive a premium device. There are no bubbles trapped within the shell, and the glossy piano black finish coupled with the transparent shells make these a classy pair of IEMs that deserve the Capital Studios trademark.


Consumers have a plethora of choices to customise the monitors to their liking. On the UE Pro website, for example, there are 4 categories: translucent, opaque, speciality materials, and designer editions which house an even larger number of colors and design options. Once the color is decided, customers are offered even more choices ranging from the length and color of cable to the type of carrying case itself. While not necessarily unique, personalisation is a great way for a company to present non-standard products in a way the customer opts for. Perhaps a suggestion would be to go even further and offer more of a selection of wooden faceplates which have been in demand ever since Heir Audio’s avant-garde implementation of them in their series of custom monitors. 

Fit & Isolation

I felt this category deserves a separate mention as this is the sole purpose of custom IEMS; To deliver a seal-perfect fit and provide superior levels of isolation. With that said, the fit of the UERM is quite deep, which does take a bit of getting used to. The tight seal enables you to become isolated from the outside world and consequently immersed in the world of music. It is also for this reason that you are able to play music at a much lower volume since there is no need to drown out the exterior environment. Once you get past the initial deep fit, comfort levels substantially improve to the extent where you can sleep with them in.

Sound impressions


As to be expected for an IEM designed for professional studio use, the signature is perceptually flat and consequently neutral. Every part of the frequency range remains well-proportioned with one another and there is no coloration or boosts in any part of the spectrum. I was also surprised to hear that the UERM possesses a hint of a warmth, perhaps aided by its transparent and revealing nature. Clarity levels are nothing short of outstanding which means vocals are not only intelligible but micro-details can easily be discerned. Next to detail-hungry sets such as the Rock-it Sounds R-50 and the DUNU DN-2000J, the UERM bests them in the revelation of nuances but trails behind in rendering notes with laser-like precision. Instead, more emphasis is placed in exposing the various components of a track in a slightly laidback manner as opposed to the two TWFK sets confronting you upfront with bouts of detail.       


Starting from the sub-bass, there is good extension and depth which aids in giving the UERMs that subtle warm tonality. With that said however, both the Earsonics Velvet in warm mode and the Heir Audio IEM 8.0 far surpass the UERM in quantity and scale of sub-bass. Thus, these IEMs would not be suitable for bassheads or even those that require more than an adequate amount of bass. As for control, the UERM edges both IEMs in realism with an impressive true to life reproduction of bass. Perhaps only what I would deem the king of bass, the Shure SE846, dethrones the UERM’s in accuracy of bass with greater levels of texture and low-end extension. Coming onto the mid-bass, the frequency range presents as flat, punchy and real with noticeably more heft than that of the Vision Ears VE5 CIEM. For what it’s worth, the flat signature of the bass coupled with the faithful representation of low frequencies makes for a very enjoyable low-end that would otherwise be quite hard to dislike. A job well done.


There is a mild U-shaped imposition on the midrange frequencies that gives the UERM a slightly more laidback signature than the DUNU DN-2000. At the same time however, this brings about more of a sense of airiness in tracks as well as a heightened perception of space. Akin to the lower frequencies, the midrange is very neutral and extremely transparent in the recordings of all genres. This is by far the most revealing IEM I have ever heard to date and hence it suits its purpose as an IEM for studio monitoring and mastering. While not its primary intention, the UERM can equally be used by audiophiles for casual listening as the midrange feels very natural and places you within the context of a studio setting. Even though the midrange is relatively flat, the UERM fails to be devoid of emotion due to the natural tones it presents with.  


Treble has great extension, sparkle and clarity within all of the tracks that the UERM was tested with. Some may consider them too bright but I personally feel that they are very much in line with the rest of the spectrum. On some tracks, however, the tonality of the treble does tend towards harshness and it is not as smooth as the top-end spectrum of the Vision Ears VE5 or even the DUNU DN-2000 for that matter. With time, though, harshness does settle down and they are very easy to listen to without being fatiguing at all.

Soundstage & Imaging

The soundstage of the UERM is phenomenal with a wide-reaching projection of sonic cues in all directions. Out of all of my IEMs, the UERM has enough of a perceived soundstage to rival closed-back headphones and bests even the Heir Audio IEM 8.0 in this regard. Like the Shure SE846, there is decent forward to back projection of sound to give a good scale of depth. Imaging is world-class and is very much reminiscent of the Sennheiser HD800’s superior perception of vocals and instruments.


The UERM is on par with both the Fiio X5SG and the iBasso DX90 though the latter presents with a brighter than neutral offering with slightly better detailing and separation. The Fiio however due to its smoother tonality tames down the slightly harsh treble that the UERM renders. Both drive the 35 Ohms IEM easily with little to no hiss and background noise.


Overall, the UERM has left me very impressed. It is open and revealing, yet humble in its approach. What it set out to do, it certainly achieves and more with great rendering of details and a natural sound. Without emphasis on any part of the frequency range, the UERM is neither dull nor clinical but instead full of truthful charm. The huge array of customization options and significantly fast build times have allowed UE to accrue an exceptional customer experience. Price is certainly an obstacle however as at $999, the model is by no means cheap. In my opinion, though, it is a well-spent investment for those wishing for a truly reference sound that is faithful to recordings whether it be for exposing the best from tracks or revealing flaws from poor mastering. Whatever the reason, accuracy and neutrality are guaranteed with this set.

Unless otherwise indicated, this is a preview article for the featured product. A formal review may or may not follow in the future.