Comment 124 for bug 190754

"As far as I know, dmix is setup by default in ALSA when no asound.conf file is present."
Conn: that's what I thought too (that's what the ALSA wiki says). But my experience is that I get not software mixing unless I specifically add dmix to asound.conf , and I tried this on 3 completely different computers (where only one had more than one sound card) and at least 3 different Ubuntu versions. That's one of the reasons PulseAudio is so interesting to me. It makes software mixing easier to set up, plus adds individual volume control for each stream, and lets me easily select the default soundcard.

I will try the proposed kernel and will report back.