After carefully reading through this whole thread, I realized, people with both Intel and AMD processors as well as nVidia and AMD GPU cards have the same problems. I am currently trying to reliably recreate this problem with standard software, no luck so far. Has anyone here (if anyone is still here and not everybody has left their Yamaha card for good) gotten the audio drop outs with a CPU/GPU stress test? I was certain, it had to be a GPU, maybe even a DirectX related problem.
It’s weird, because I sit here, HOPING for the card to get its audio drop outs but they don’t happen, even if I have both a CPU and a GPU stress test running in the background and all is going on smooth.
I have also borrowed a Scarlett 2i2 for testing and verification purposes, this card works like a charm.
The only thing that is easily recreatable is opening a game in full screen mode and alt-tabbing out of it. Minimizing the window always causes audio drop outs, sometimes maximizing it does, too.
Still, the only other way for me to reliably recreate this problem is to start OBS and run a somehwat graphically demanding game at the same time. Doesn’t even need to be that demanding. But for this “recreation” it’s easy to point the finger to the evil OpenSource software even though with other audio cards this problems do not occur. 
I’ll keep looking for recreations, I’ll let you know when I found a method.