Alright so after months of research, hunting, buying and testing, here my impressions of my current stuff.
Home use:
JDS Atom + Khadas Tone Board + Focal Elear with Focal Clear Pro pads and custom cable
The Atom and Tone Board are rather "cheap" devices compared to other options on the market. They may lack some features or connections. But it's enough for me and they sound excellent, very transparent, clear and neutral, without any coloring going on.
The Focal Elear with stock pads are too bass heavy and warm for me. But the Clear pads change their characteristic and transform them into the Elex (which is an Elear with Clear pads). Sounds amazing, so much detail, structure and emotions. I really love them. They are very good at staging and positioning the different sound. They create a rather intimate sound stage, so if you're looking for a huge spaceous stage, those aren't for you.
But that's by design. They are incredibly engaging headphones that really pull you in and the more intimate sound stage supports that.
Build quality is also great, but they are on the heavier side. Very comfortable, but for example the Shure SRH1840 are even more comfortable because they are way lighter. Still, overall very impressive headphones. Open back of course, so not usable outside because there is no isolation at all.
Traveling:
FiiO X3 2nd Gen + FiiO A5 amp with
Option 1: ISN H40 IEMs
These are "Chi-Fi" In-Ears, bought from PenonAudio. First of all, the packaging does not look premium and the presentation of the device is not great despite it's price. But that's not their intent. These are IEMs that sound as good or better than others that cost double the price. But first, what's in the box:
As you can see, lots of different eartips, so finding the perfect one for you will be no problem. Shout outs to the cable, it's actually one of the best I've ever seen. The IEMs themselves look black but the sun reveils their nice blue/violet color. Their size is rather big, but the cable goes over your ears so theres no weight pulling down so they are very comfortable and have a good shape.
Now the sound: What can I say, they are special. Their tuning is just right. Sound signature is rather warm, engaging and very enjoyable. They are detailed but don't shout it in your face. Bass is warm but well defined, the mids are just perfect. I can't pinpoint what it is, but the sum of it's parts make them great. Good wide soundstage for IEMs and overall a lot of fun. Not for bassheads that want maximum slam though. Still, for the price I'd say you can't buy anything better, not even full size headphones. (They cost 195$ fyi).
Option 2:
Ultrasone Signature Pro
Closed back headphones, I use them for longer trips and to take them with me. They come in a nice travel case but can also be folded in all directions and are actually the best portable headphones in my opinion. They are very sturdy and build like a tank. High quality materials that will last forever. Light and comfortable, nice soft pads. They can get warm over time of course, but they are a bit better than most other closed back headphones in this regard.
Sound: They sound a bit like a you would describe German engineering. Extremely clinical, analytical, clear and efficient. It's suprising how much detail they are able to reproduce. They are like the opposite of the Focal Elear. While the Elear are great at creating a virtual space where you feel like you are in a room where the music happens and pulls you in, the Sig Pro don't give a damn about that. Every sound is presented like a seperate, individual element. They have a rather big width for closed back headphones, but they don't create the feeling of a real stage. Instead, they overwhelm you with their incredible precision, seperation and crystal clear sound. It was strange at first, coming from the Elear. But as the name suggests, these are headphones made for professional studio use, to hear every little sound. Which they do amazingly well and you can hear sounds / nuances of sounds that just aren't there on other headphones.
Bass is very crisp and controlled, highs are outstanding and not too sharp, mids are also just right.
All in all, very happy with all of them. They are very different but great in their own regard. Was lucky to buy the Elear and Sig Pro way cheaper than the current street prices.