Passthrough via S/PDIF without pulse

[daharn]

During the last couple of months, I have unsuccessfully tried to set up audio pass through via my Pi 2 with an HifiBerry-card. When pass through is enabled, no sound can be heard from my soundbar, only the subwoofer kind of "rumbles" a little.

I partly blame my audio device (Samsung HW-D 450), because it seems to be working for other people with the same setting otherwise. I knew, however, that it was able to play pass through audio when connected to my windows PC using the pass through settings of mpc-hc.

I now noticed that, when using Ubuntu and VLC player, I can only get pass through to work if I select "playback/recording through the pulseaudio sound server" as the audio device. If I choose the optical digital output directly ("Digital IEC958 ..."), I can reproduce the faulty behaviour of the raspberry under xbian described above.

So the question is: What could cause my soundbar to properly handle pass through streams only when pulse audio (or Windows) is involved? Is there a way I can get past these limitations? Is pulse still unsupported in xbian?