After upgrading to Karmic, I had no sound in Amarok. I tried to force myself to use Rhythmbox, the "official" player for Ubuntu, but I just can't stand it, especially for Internet streams.

So, here's the fix to make Amarok work properly:

sudo apt-get install phonon-backend-xine

Followed by:

sudo apt-get remove phonon-backend-gstreamer

Of course that's the console way - you could also open the Synaptic package manager from the System + Administration menu and install and remove the packages with point-n-click. Just look for "phonon-backend-xine", install it, then look for "phonon-backend-gstreamer" and remove it.

I don't know if this will affect a new installation of Ubuntu 9.10 or not.