Hello, This is my first message on this mailing list, I'm a standard Ubuntu user and a home-cinema amateur. I basically use Ubuntu as a mediacenter hooked to a videoprojector and a 5.1 digital decoder sound system. I'm a little confused about Alsa and Pulseaudio and their respective purposes. My problem is to get the AC3 (dolby digital) and DTS flux from movies decoded by my 5.1 Amp. My sound card (HDA intel - ALC889) is connected to my logitech Z5500 decoder with an optical cable (toslink). I'm using mplayer or VLC with s/pdif pass-through enabled but I can't get any sound out of my speakers. Ubuntu 10.10 currently use Pulseaudio 0.9.22. Can someone explain to me in broad terms how things should work through Pulseaudio and Alsa? And what I should do to get ac3/DTS decoded by my amp? Thank you. Vincent