Possible solution - at least it worked for me
I encountered the same problem. Finally I started artsd in a console window and was pointed to a missing "libxine.so.1" when trying to play a mp3-file with Noatun.
Solution which gives me full sound support: Get the latest xine-lib 1.1.7 sources and compile it. the libxine.so.1.1.7 and symlinks are written to /usr/local/lib by "make install", but I think you'll need symlinks libxine.so and libxine.so.1 in /usr/lib. If you do that, Amarok will play, too.
Hope it helps,