Today a Linux 2.6.24 kernel appeared in Debian unstable, so I immediately gave it a try, to see if it did anything to the sound issues on my Zepto Znote 3214W laptop.
First thing, the 2.6.24 kernel has ALSA 1.0.15 which is needed. The Realtek ALC268 doesn’t work with earlier versions of ALSA.
Still the sound didn’t work. I then tried setting different values of model= for the snd-hda-intel module in /etc/modprobe.d/sound, and the setting model=acer did the job.
The whole line is
options snd-hda-intel index=0 model=acer
There is one remaining problem: when I plug in headphones the speakers aren’t turned off automatically. For now I’ll just have to do that manually, but I believe it is fixed in a later version of ALSA.