ALSA driver snd_hda_intel works for playback as of 2.6.18-rc1.
MacBook with Debian 4.0 Etch has no problem with sound. Although, you may need to run alsaconf as root.
If you hear any distortions even when all of the mixer settings are at least 20% below their maximum, it might help to load snd-hda-intel with the 'position_fix=1' option. In the file /etc/modprobe.d/alsa-base, change the line
install snd-hda-intel /sbin/modprobe --ignore-install snd-hda-intel $CMDLINE_OPTS && /lib/alsa/modprobe-post-install snd-hda-intel
to
install snd-hda-intel position_fix=1 /sbin/modprobe --ignore-install snd-hda-intel $CMDLINE_OPTS && /lib/alsa/modprobe-post-install snd-hda-intel
