I tried to play back some ?mp3-pro? encoded files using xineUI and Amarok. They played back with no errors, but 
when i switched from direct hardware output (hw:0,0) to dmix the problem appeared. Files are  still played back with no errors,
but some strange noise appeared on frequency of about 4 -5KHz. this sounds like clicks, and is really annoying. 
Switching off dmix solve the problem, but blocks sound output=(
I am pretty sure that this is not only XINE's problem, but also some bug in ALSA's dmix, but Idonot understand how to handle this.
My hardware:
Analog Devices AD1881 also known as intel 8x0
My software
Amarok 1.4.5 KDE 3.5.5. OpenSuSE 10.2
XINE: latest from packman's rpm store.
Mail me for feedback if you need any=)