Thank you for your quick response!
Luckily I was still in time to cancel the order (it was only 8 euros, but l still prefer to not trow money down the drain and the "adapter" down the bin).
Also I'm gonna give my impression on the Hidizs S9 Pro Plus Martha once it arrives, it was ordered from the official website so maybe someone could find my experience interesting.
So it did finally come. Paid 81€ (90$) on the original
site, this is definitely the cheapest option, it costs 99€ on Aliexpress and a whopping €170 on my local Amazon!
Really nothing to report, the product was sealed and it did take 6 business days to arrive in my european country from the order day, the package was sealed and it looks new so I assume it is.
I didn't have to pay any additional customs fees but your milage may vary ofcourse.
The package contains the product, a short USB-C to USB-C cable, a USB-A to USB-C adaptor and the manual.
There's no actual rating on max recommended impedance but I can say that it gets really loud with my 250ohm DT 990 PRO at 50% volume, I use it around 22/24%.
I initially thought it had two knobs but they just two physical buttons, volume up and volume down, it barely heats up, maybe they really improved this aspect with this new model, basically a non issue.
The led on the logo changes color based on the windows audio settings and it can't be turned off, if you don't like it there's a simple solution: just turn it around.
Sadly I cannot really speaks about sound quality, I don't have much reference or any equipment and experience to test it. In my ears it sounds really good, it's the only thing I can say.
Hope someone found this usefull.