Lately I had nothing but trouble with my sound setup. The full chain looks like this:
alsa (pulse plugin)-> pulseaudio (jack plugin) -> jackd -> firewire soundcard
This works fine, except for flash in firefox and Chrome. I have reason to believe that the tail end of the chain is okay, because every other source of audio, using pulse or jackd directly works fine.
On the front end I made some experiments, like connecting alsa directly to jackd, but this also causes trouble with flashplayer: playback stops after like 20 seconds and firefox freezes.
This made me believe that there is something wrong with the alsa stuff.
Now I do have a custom kernel (3.8.2) but the rest of the system uses regular debian "stable" stuff. Can it be that the kernel is "too new" for the alsa libs?