Yeeeaaaaahhh! Giga is working fine!
For those who had problems like me: click right on the kx mixer or the kx icon, and choose "buffer settings" (in french, on my computer: "configuration tampons")
Just change the GSIF settings (the last, back in the window). I first setted it to the max, it was not good. Then I tried to reduce the size, and I restarted my computer: the sound was OK!!!but latency. I finely setted to 256 samples, then restarted. And now it's fine! I don't remember what was the original setting (128 or 256) but I think there's nothing to understand!..Do the same thing, and hope for you it will work.