RIGATIO
Headphoneus Supremus
Nice write up, you described this peak well- as indescribable Its strange indeed, like its not a typical sibilance or sharpness but rather thin, annoying ringing.For me, they really did lack detail. On certain tracks they just sounded out of whack to me... dull. Too smooth. Unlike anything I've heard other than my single DD Ety ER2 - for me it was just an enahnced version of this. I mean, smooth is nice, but in some music there actually is roughness... in voices, sounds, and I just wasn't hearing it. I do think it's a DD / BA thing. I also prefer the ER4 (which is BA) to the ER2. Anyway what's funny is that although I'm saying that for me the treble was a bit dulled out, I did hear a certain peak occasionally that I found irritating. Not sibilance, something else... I'm not expert enough to identify it, but I wouldn't be surprised if I was picking up your 5k peak.
The form factor is incredible though, so small and light. And the cord was good and comfortable. Great for grab and go, could throw them around a little bit... maybe just pocket them and throw them on while getting on a bike, whatever... wouldn't have to be babied like the much more delicate feeling larger shells and connectors of the u12t and Monarchs.
One other thing about the Xelento - on some tracks I felt like the voice of the singer was like literally in each ear. Not outside in some kind of nice sphere around my head, or a few rows in front of me on a stage, etc..... but rather as if the music was happening right on/in the ears. I can see how some might be into it but I found it almost jarring. Maybe something one could get used to.
When it comes to the detail as every nuance which is recorded, i can hear every little detail as on the u12t or the Monarch 2 but put in a more laid back manner. They for sure lack texture and texture is something which for many is included under the term of "detail".
The stage you described similarly as i hear on them but to me they sound more grand and bigger than the u12t. The u12t puts you in a big room, the X2 present more a big wall of sound but the vocals arent as distant as on the u12t. Everything seems closer but also bigger and wide, at least to me.
Anyways, im still keeping the u12t as they are overall less problematic for me. But still kuddos to Beyerdynamic for making such a great upgrade to the Xelentos OG.