Hallo again!
I'm so happy today. After changing expensive usb cables, inspecting the device inside, testing device with other pc's with windows 10 (on windows 8.1 worked every time), I finally solved my problem. Wa7 was recognised by my win10 desktop pc with an old, cheap usb cable. I've tested 7 usb cables, mine or borrowed from my friends: Charlin, Qed, Oelbach, Kimber, , Audioquest, Chord and Tellurium. Nothing worked.
Later last year, after almost 2 years of working fine, wa7 gen1 wasn't recognised by my win 10 anymore. It said " usb not recognised error 43". I was using an Qed reference usb cable. I was so mad. I wrote to Woo audio and their solution was to send the device back to them and upgrade to 2nd gen for 400 usd. Since I'm not in the US, this wasn't an option for me. Too long, too expensive. Today, after installing the new win 10 update, I thought I'd give it a try. I was lazy enough not to go next room where I've stored the expensive cables, so, I picked up the cheap one that was in my desk. Big surprise, it worked. I thought that win 10 update did something and changed the cheap cable with the expensive ones ( qed and charlin). The device doesn't worked. Canged back with the cheap one, worked again. I did restart the pc, shut down, everything was ok. I still don't know what caused this issue is ( maybe my motherboard or the pc source), since the device worked on my win 8.1 laptop with all the above cables and my fiio k5 worked also with the same cables on win 10 and win 8.1.
I hope it will last and hopefully woo audio will include a tested usb cable with their products.