Settings-System-Audio

[gkusiak]

I need some help - this has always been a grey area in my knowledge and understanding and I'd like to straighten it out please:

My setup is: xbian (v19) - HDMI 1 out to my display. Display has Toslink Optical output that I use to squirt the audio into my 5.1 all-in-one unit.

Every so often (like at a major update of xbian) I have to mess around with the setting here to get sound consistently.
I guess I don't know whether to select the ALSA HDMI, the non-ALSA HDMI or the PI options in xbian settings - what are the differences?

I've poked around on the kodi-raspi subforum to no avail. Help? getting the picture of the logic/flow in my head would be most helpful.

Thank in advance.