Comment 2 for bug 448024

It is possible to get passthrough working, in Karmic if I want to use passthrough I have to go into the audio applet and set the Profile to 'Analog Stereo Output' (I'm guessing this forces pulse to release it's lock on the digital output) and then adjust the options for whatever mediaplayer to use Alsa directly and ensure the passthrough option is checked.

This is still unacceptable as you have to keep switching the output profile and obviously isn't obvious to the end user. I feel the lack of proper passthrough support is really hurting Ubuntu as a modern multimedia capable OS, it definitely renders it almost useless as a media centre type PC. This reason alone makes Pulseaudio a step backwards from Alsa in my opinion.