Sound:
Low impedance sources. Largest included triple-flange silicone tips modified to seal in my large ear canals while maintaining the same ear tip length (cutting off smallest flange and putting it on the nozzle before the remaining double-flange tip).
Tonality:
Etymotic's typical, very neutral, coherent and natural midrange and treble with a bit more bass presence compared to the reference-flat, sterile, uncoloured ER-4S/ER4SR lows.
Basically flat, neutral midrange and treble along with a moderate bass emphasis that starts in the middle fundamental range and gradually gains quantity towards the sub-bass where its climax is reached. Therefore also just a bit of warmth.
Still far from bassy; the lows are more or less of the same quantity as those of some other manufacturers who chose to go for in a neutrality-oriented in-ear.
Let’s talk about the treble and midrange: these areas sound very neutral and flat to me during music listening and sine sweeps. The very mild lift in the presence range known from other Etymotic in-ears also appears a little less present to me. Doing sine sweeps and listening to music, nothing in the midrange or treble sticks out and nothing seems to be lacking either except for a minor recession around 7 kHz.
Due to this, the timbre is extremely natural and all instruments as well as vocals sound ideally neutral and straight to the point uncoloured to my ears.
Now to the bass: listening to sine sweeps, I hear that its emphasis starts around the 500 Hz mark, and then gradually climbs down to the sub-bass where its climax is reached. As mentioned, the emphasis is however not that much at all – compared to Etymotic’s diffuse-field flat in-ears in the lows, the ER4XR has got ca. 3 dB more quantity at 100 Hz, ca. 4 dB more at 50 and a bit less than 5 dB at 30 Hz and below, which is in the range of the mild elevation of other in-ears that are widely accepted as mostly neutral sounding in the bass.
The implementation is really well made and as it rises gradually, so the bass blends into the other frequencies extremely well without masking of colouring them. Vocals are also widely unaffected by the lift and only very low voices in the lower fundamental range gain a bit more (natural sounding) body without sounding coloured or artificial – the tonal balance is still great and the ER4XR sounds still very balanced without being as “sterile” or flat and entirely uncoloured as the ER4SR.
As for a take on a tuning to include a compensation for the lack of the presence of mechanical vibration/body-borne noise present on in-ears, this is a very good outcome. And I have to say that the implementation of that moderate and overall still pretty mild emphasis is also quite addictive and something I also really like.
Resolution:
Great for a single-BA in-ear.
Very nimble, fast, especially coherent and very detailed. Highly controlled.
Bit less clean sounding in the bass than the ER4SR, though. Otherwise similarly great.
Soundstage:
The soundstage surely isn’t the largest in all directions, however just as with my ER4S, I have never perceived it as small or congested at all but averagely large with a very good width-to-depth-ratio and an almost perfect spherical and three-dimensional illusion with just slightly more spatial width than depth. Therefore, while not very large or expansive but only "average" in this regard, the soundstage appears three-dimensional and authentic to me.
Precise instrument placement, layering and separation. Sharp and realistic imaging. No fogginess.
(Therefore, the ER4SR and ER4XR have got a) Slight improvement over my ER4S in this area, although it's only audible in a direct comparison. ER4SR even slightly cleaner than the ER4XR in this regard, though.
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Compared to other Balanced Armature In-Ears:
Ultimate Ears Reference Monitors:
The general tonal direction in the lows is widely similar among these two in-ears – the only real difference is that the ER4XR’s bass emphasis starts a little lower wherefore its middle root is slightly less warm compared to the UERMs’. Both have got identical amounts of midbass quantity while the Ety has got slightly more presence in the lower midbass and sub-bass. Except for the presence range that is just slightly forward on the ER4XR, both sound comparable to me in the midrange. Going up with the sine sweeps, I can hear a wide, moderate recession in the UERMs’ middle treble along with a narrow peak around 10 kHz that can sound a bit harsh if a single note hits it exactly.
In the treble, the ER4XR is more linear and even in comparison, wherefore it also sounds more authentic and realistic here to me.
In terms of bass speed and control, as well as detail retrieval and instrument separation, the UERM is ahead.
InEar StageDiver SD-2:
The SD-2 has got the fuller and warmer root as well as midrange in comparison as well as a little more overall bass quantity. The SD-2’s treble is one of the few in-ears’ upper ends that sounds almost as even and authentic as the Ety’s while the StageDiver has got a little less overall treble quantity and takes it to a smoother and more laid-back presentation.
The ER4XR’s bass is a bit faster and less soft than the SD-2’s.
The InEar’s soundstage is larger in all directions and more three-dimensional while instrument separation and spatial authenticity are comparable among the two.
Etymotic ER4SR:
Being used to speakers, in-ears and headphones that head into the flat/neutral direction, I never found my ER4S or the ER4SR to lack bass or sub-bass at all, it just wasn’t emphasised and spot-on flat to the diffuse-field target response to my ears. Some people however, who really liked the ER4 series’ midrange and treble, wanted a little more bass impact at times. And this is exactly what the ER4XR provides: basically the same sound signature as the ER4SR, however with a bit more bass quantity. It's not that much but enough to give the ER4XR a bit more sub-bass and midbass quantity along with a little more warmth in the lower root without affecting the midrange balance.
Both in-ears sound equal to me when it comes to detail retrieval, except for that the ER4SR sounds slightly cleaner in the lows.
The ER4XR has got an almost identical soundstage to my ears that is just ever so slightly less deep with the minimally less precise separation in direct comparison.
Conclusion:
Mostly like the ER4SR but with a more pronounced bass that is however still in the territory of mostly neutral sounding in-ears.