this is one of those times when you find the solution before sending the email to the list. Just in case anyone else comes across this:
after the latest batch of updates yesterday to xorg (which broke compiz and needed to be upgraded from testing repo, but that should be a separate issue) KDE 4.3.1-1 and also to alsa-plugins-pulseaudio-1.0.21-2 and kde-settings-pulseaudio-4.2-12.1 - no more sound <cue sobbing and wailing>
starting 'pulseaudio -D' now logs
Sep 18 12:54:34 xulu pulseaudio[8290]: module-alsa-card.c: Card '0' doesn't exist: Permission denied Sep 18 12:54:34 xulu pulseaudio[8290]: module.c: Failed to load module "module-alsa-card" (argument: "device_id=0 name=pci_1106_3059_sound_card_0 card_name=alsa_card.pci_1106_3059_sound_card_0 tsched=1"): initialization failed.
$ ll /dev/snd/ crw-rw----+ 1 root audio 116, 7 Sep 18 12:07 /dev/snd/controlC0 crw-rw----+ 1 root audio 116, 6 Sep 18 12:08 /dev/snd/pcmC0D0c crw-rw----+ 1 root audio 116, 5 Sep 18 12:08 /dev/snd/pcmC0D0p crw-rw----+ 1 root audio 116, 4 Sep 18 12:07 /dev/snd/pcmC0D1c crw-rw----+ 1 root audio 116, 3 Sep 18 12:08 /dev/snd/pcmC0D1p crw-rw----+ 1 root audio 116, 2 Sep 18 12:07 /dev/snd/timer
SOLUTION - fix the permissions, duh :)
# chmod o+rw /dev/snd/*
As to why this is necessary all the sudden, I have no idea. Should I add all system users to the 'audio' group instead?
Sam