If rendering is correct while playback is not, it could be the OpenGL driver used in playback.  Rendering ALWAYS uses software and is not subject to the vagrancies of OpenGL.  With the test I did, I could not detect a playback error when using OpenGL.  Stefan, you can test this theory by changing Settings->Preferences->Playback A driver to X11 instead of X11-OpenGL (that is assuming you currently have it set to OpenGL).  It would be interesting to know for sure if F_atadenoise will then be in sync.