it works! this new firmware did the trick....kinda. for some reason i have to switch into video mode and back into pimax mode, but it works now!
fyi: without the mode-switching, it gets detected, but the monitor keeps flickering and the HMD-screens stay blank.
im off catching up on my VR-experiences, do some races in dirt rally, fly a few missions in elite and watch one of my 5 new 3d movies. thnx for the early christmas present!
ps: ill check back tomorrow if you need any additional info.
edit: after pc reboot, no more modeswitching required, just works.