WiiU another Audio driver Vice_x64 / bumping audio

Hi I am using retroarch 1.7.1 and love playing C64 on my WiiU. Everything looks good, but there is always this permanent knocking/bumping noise (200 beats per minute) . I hear that in any game, when I play SNES then everything is fine. So I guess it has sth to do with the Ax-Sound Driver. It is the only driver I got. Are there any other audio-drivers available? I also tried nightly, same noise there too. How can I get rid of that noise?! When I put down FrameDelay the bumping noise is going slower maybe 100 beats per minute. Am I the only one playing C64 on WiiU?!