Sound:
As source devices serve me some models from my inventory with a low output impedance:
As source devices I use some models from my inventory with a low output impedance. Semi-portable this is mainly my iBasso DX90.
Tonality:
Until not quite half a decade ago the UERM was definitely the most neutral, linear and flattest playing in-ear in my possession and was then replaced by the Etymotic ER-4S, which plays a bit more neutral and flatter in some places.
But one after the other: A few years before I bought the UERM, I ordered a demo model of the listener for the first time on bail (from another distributor) to see if it was worth the price to me. My first listening session ended in tears because the UERM sounded very realistic and was exactly what I was looking for: a neutral in-ear that was technically audibly superior to my Shure SE425, which was my most used in-ear at the time.
And now I own the real, custom-made UERM.
To my surprise, I also have to say that I am lucky, because the custom-made in-ear sounds in my ears almost the same as the universal demo listener, only the peak in the upper treble is in my ears a bit higher in frequency response. However, there is no guarantee that the custom-made in-ear sounds like the demo earpiece, because the sound of the demo depends on the individual ear anatomy, the angle, the insertion depth and the tips used (but since the difference was very small in my case, I would have used the universal variant if there was one available).
Tonally, the UERM is very neutral and far more neutral than most of the models on the market. But it doesn't sound as flat as an Etymotic ER-4S, even if it comes along without any discoloration and there is, as it should be, no frequency range that stands out more than another. With some experience you can also hear the small deviations with a sine generator without owning the ER-4S. So the UERM has slightly more bass and lower fundamentals than what a very flat curve would be, and also the treble around 5 kHz is a bit more relaxed than perfectly neutral. When listening to music and without the comparison to a strictly flat in-ear this is not really noticeable and the UERM definitely sounds neutral (besides, there are tolerances here, because headphones, in contrast to loudspeakers, do not have a target curve that is considered neutral by all scientists and manufacturers due to the missing structure-borne sound and the inclusion of the HRTF, as I already reported in my review of the ER-4S).
Above 10 kHz, on the other hand, the UERM makes a mistake and produces "the typical UE house sound" (= peak in the high frequencies) by having an emphasis between 10 kHz and 13 kHz that is not exactly faint. If an instrument or song hits exactly this range, but this happens rather rarely, the high frequencies can become unbearable and sharp. This is a bit unfortunate, because therefore the otherwise very good in-ear doesn't sound quite as realistic in the (high) treble as some other in-ears that sound more even.
A few years ago with fewer models in my collection as comparison I didn't really notice this and the UERM still sounds more even in the high frequencies than many other in-ears, but unfortunately not as natural and authentic as some other models that are tuned more evenly in the high frequencies (the parade example here might be the Etymotic ER-4S, which in my opinion has one of the best high frequencies in the world of in-ears regardless of price range).
The UERM can handle all genres very well if you are looking for a neutral tuning and sounds neutral, "unspectacular" in a positive sense and want an earphone free of discolouration/very low in discolouration.
This makes it a very neutral but not quite perfect neutral-flat in-ear (the Ety is not perfect neutral either, but comes a bit closer to my perception of what would be flat based on sine-sweep listening as well as compared to the diffuse-field target curve), so all people who are looking for a neutral sound should audition it if possible.
The UERR, which replaces the UERM, sounds even and authentic in the high frequencies, but at the same time has a bit more fundamental warmth and a softer bass (or generally a softer/tamer sound in comparison).
Resolution:
The UERM has a very high detail level, which can definitely be considered flagship level.
The bass is very clean, tight and fast. Here hardly any wishes remain open and the bass definitely doesn't lack detail resolution.
The midrange also has a very high resolution and fine details are easily uncovered in the voice range and voices appear vivid.
The high-frequency resolution is also very good, which is why the peak above 10 kHz is often not too annoying or unpleasant and I even know owners of the UERM who don't even notice it. The in-ear effortlessly separates individual instruments and notes in the high, mid and low frequencies.
Very fast and complex music is definitely no problem for the UERM and fast metal, complex and densely populated classical music or electronic music with fast and complex beats is reproduced completely effortlessly.
Compared to cheaper models like the Shure SE425, which served me as a reference when I got into the hobby and first listened to the UERM demo model a few years ago, the UERM is quite a noticeable upgrade, but the gap narrows when comparing models like the Fischer Amps FA-3E, UE900 or Noble SAVANNA. Compared to these, the UERM also resolves a little higher, but not as drastically different as compared to the Shure.
By the way, I also see the UERM on the technical level slightly above my Sennheiser HD 800 headphones.
The UERM is also technically audibly superior to my beloved ER-4S, especially in the low frequencies, which is particularly noticeable in very fast and complex recordings. Nevertheless, the ER-4S is by no means bad and I even prefer it tonal and therefore use it more often than my UERM.
There are however also some models that resolve even a bit better than the UERM, some even in my inventory, even though differences and gaps in performance are much smaller than when comparing the UE to lower-tuer, cheaper in-ears. Nonetheless the UERM is an in-ear that definitely deserves flagship status.
A bit more resolution than with the UERM is certainly still possible, but I rarely miss the last few percent with my UERM, but you definitely shouldn't expect a significant increase with other models. And for that case, I own other in-ears that also head into a quite neutral direction.
Soundstage:
The stage is quite large and three-dimensional, with a good and sharp separation of instruments and precise positioning of individual instruments. No, the UERM doesn't have the best, biggest or most precise stage I've ever heard on an in-ear, but it's very good and staggered. If I could choose, I'd take the stage of the UE18 Pro (which was overall too discoloured, especially in the midrange, for my preference) paired with the highs of the ER-4S and the technical level of my UERM, InEar ProPhile-8 or the NocturnaL Audio Atlantis - that would be an almost perfect and neutrally tuned in-ear for me.
What struck me about the UERM was that its stage is quite changeable and can turn out rather different depending on the recording: In some recordings the stage of the UERM appears small and compact, whereas in others it appears normally big and in others even very big, airy and almost boundless. Here the in-ear uncovers the weaknesses of spatial mixing and recording mercilessly, but rewards its owner also with a beautiful and plastic stage in very good recordings and is not limited only to the front and the sides, but can also sometimes go backwards or up (in a non-binaural classical recording I was a bit shocked when I first listened to a man coughing right behind me a couple years ago).
As source devices serve me some models from my inventory with a low output impedance:
As source devices I use some models from my inventory with a low output impedance. Semi-portable this is mainly my iBasso DX90.
Tonality:
Until not quite half a decade ago the UERM was definitely the most neutral, linear and flattest playing in-ear in my possession and was then replaced by the Etymotic ER-4S, which plays a bit more neutral and flatter in some places.
But one after the other: A few years before I bought the UERM, I ordered a demo model of the listener for the first time on bail (from another distributor) to see if it was worth the price to me. My first listening session ended in tears because the UERM sounded very realistic and was exactly what I was looking for: a neutral in-ear that was technically audibly superior to my Shure SE425, which was my most used in-ear at the time.
And now I own the real, custom-made UERM.
To my surprise, I also have to say that I am lucky, because the custom-made in-ear sounds in my ears almost the same as the universal demo listener, only the peak in the upper treble is in my ears a bit higher in frequency response. However, there is no guarantee that the custom-made in-ear sounds like the demo earpiece, because the sound of the demo depends on the individual ear anatomy, the angle, the insertion depth and the tips used (but since the difference was very small in my case, I would have used the universal variant if there was one available).
Tonally, the UERM is very neutral and far more neutral than most of the models on the market. But it doesn't sound as flat as an Etymotic ER-4S, even if it comes along without any discoloration and there is, as it should be, no frequency range that stands out more than another. With some experience you can also hear the small deviations with a sine generator without owning the ER-4S. So the UERM has slightly more bass and lower fundamentals than what a very flat curve would be, and also the treble around 5 kHz is a bit more relaxed than perfectly neutral. When listening to music and without the comparison to a strictly flat in-ear this is not really noticeable and the UERM definitely sounds neutral (besides, there are tolerances here, because headphones, in contrast to loudspeakers, do not have a target curve that is considered neutral by all scientists and manufacturers due to the missing structure-borne sound and the inclusion of the HRTF, as I already reported in my review of the ER-4S).
Above 10 kHz, on the other hand, the UERM makes a mistake and produces "the typical UE house sound" (= peak in the high frequencies) by having an emphasis between 10 kHz and 13 kHz that is not exactly faint. If an instrument or song hits exactly this range, but this happens rather rarely, the high frequencies can become unbearable and sharp. This is a bit unfortunate, because therefore the otherwise very good in-ear doesn't sound quite as realistic in the (high) treble as some other in-ears that sound more even.
A few years ago with fewer models in my collection as comparison I didn't really notice this and the UERM still sounds more even in the high frequencies than many other in-ears, but unfortunately not as natural and authentic as some other models that are tuned more evenly in the high frequencies (the parade example here might be the Etymotic ER-4S, which in my opinion has one of the best high frequencies in the world of in-ears regardless of price range).
The UERM can handle all genres very well if you are looking for a neutral tuning and sounds neutral, "unspectacular" in a positive sense and want an earphone free of discolouration/very low in discolouration.
This makes it a very neutral but not quite perfect neutral-flat in-ear (the Ety is not perfect neutral either, but comes a bit closer to my perception of what would be flat based on sine-sweep listening as well as compared to the diffuse-field target curve), so all people who are looking for a neutral sound should audition it if possible.
The UERR, which replaces the UERM, sounds even and authentic in the high frequencies, but at the same time has a bit more fundamental warmth and a softer bass (or generally a softer/tamer sound in comparison).
Resolution:
The UERM has a very high detail level, which can definitely be considered flagship level.
The bass is very clean, tight and fast. Here hardly any wishes remain open and the bass definitely doesn't lack detail resolution.
The midrange also has a very high resolution and fine details are easily uncovered in the voice range and voices appear vivid.
The high-frequency resolution is also very good, which is why the peak above 10 kHz is often not too annoying or unpleasant and I even know owners of the UERM who don't even notice it. The in-ear effortlessly separates individual instruments and notes in the high, mid and low frequencies.
Very fast and complex music is definitely no problem for the UERM and fast metal, complex and densely populated classical music or electronic music with fast and complex beats is reproduced completely effortlessly.
Compared to cheaper models like the Shure SE425, which served me as a reference when I got into the hobby and first listened to the UERM demo model a few years ago, the UERM is quite a noticeable upgrade, but the gap narrows when comparing models like the Fischer Amps FA-3E, UE900 or Noble SAVANNA. Compared to these, the UERM also resolves a little higher, but not as drastically different as compared to the Shure.
By the way, I also see the UERM on the technical level slightly above my Sennheiser HD 800 headphones.
The UERM is also technically audibly superior to my beloved ER-4S, especially in the low frequencies, which is particularly noticeable in very fast and complex recordings. Nevertheless, the ER-4S is by no means bad and I even prefer it tonal and therefore use it more often than my UERM.
There are however also some models that resolve even a bit better than the UERM, some even in my inventory, even though differences and gaps in performance are much smaller than when comparing the UE to lower-tuer, cheaper in-ears. Nonetheless the UERM is an in-ear that definitely deserves flagship status.
A bit more resolution than with the UERM is certainly still possible, but I rarely miss the last few percent with my UERM, but you definitely shouldn't expect a significant increase with other models. And for that case, I own other in-ears that also head into a quite neutral direction.
Soundstage:
The stage is quite large and three-dimensional, with a good and sharp separation of instruments and precise positioning of individual instruments. No, the UERM doesn't have the best, biggest or most precise stage I've ever heard on an in-ear, but it's very good and staggered. If I could choose, I'd take the stage of the UE18 Pro (which was overall too discoloured, especially in the midrange, for my preference) paired with the highs of the ER-4S and the technical level of my UERM, InEar ProPhile-8 or the NocturnaL Audio Atlantis - that would be an almost perfect and neutrally tuned in-ear for me.
What struck me about the UERM was that its stage is quite changeable and can turn out rather different depending on the recording: In some recordings the stage of the UERM appears small and compact, whereas in others it appears normally big and in others even very big, airy and almost boundless. Here the in-ear uncovers the weaknesses of spatial mixing and recording mercilessly, but rewards its owner also with a beautiful and plastic stage in very good recordings and is not limited only to the front and the sides, but can also sometimes go backwards or up (in a non-binaural classical recording I was a bit shocked when I first listened to a man coughing right behind me a couple years ago).