The audio system needs to be re-designed, having multi-audio feature enabled (if its possible)
I have made a test on the macbooks version of elive where this new audio system works and very good, what i dont know if is that works for any machine well or just for macbooks, please try the version of macbooks (everybody is welcome!) and post on this thread if the audio works without problems and playing misc things in the same time (for examplme youtube + xmms + videos, etc), of course without doing any "extra" configuration at the audio than the default way is working (don't touch ESD configurations !))
Remember that the macbooks version of Elive is NOT made for normal machines and elive can't works as well the normal version for normal machines, use it for tests only