When it comes to a flexible audio setup Alsa starts to suck … hard. If you want output mainly on S/PDIF (be it optical or coax), automatically upmixed to 5.1, then encoded to A52 so your receiver will eat it, but sometimes your general AC3-passthrough 5.1 movie, sometimes maybe even output to your regular analog output … then its quickly becoming clear that ALSA is basically a driver framework, and not a end-user audio application. I found that most audio middlewares i’ve known sucked quite hard: Jack is too unuseable, arts or phonon never did their job, esound is kind of … dead. So what’s left? PulseAudio is left! Its setup seems very quirky to firsttime users and if you come with some strange distro-configuration (*cough*ubuntu*cough*) you may want to throw it against your wall … but actually its super flexible and nice.
If you have a similar setup to mine – read on!