No sound on Gateway NV55SO9u

[ravensrest]

I have a Gateway NV55SO9u laptop. It has an AMD Hudson Azalia (rev01) sound controller. ALSA setup runs OK, but when I attempt to play the test sound, no matter if I run any pup version 5.5 or 5.6 I get this message:

ALSA lib pcm_dmix.c(snd_pcm_dmix_open) unable to open slave
aplay: main:682: audio open error: No such file or directory

I also get that error message if I try to run aplay from the console. I realize it is telling me there is a file missing, but isn't that file supposed to be included in all versions 5.5 or 5.6? If not, where can I get it?
Thanks,
BS

EDIT:
Since my original post I have discovered that the sound works in Slacko 5.5, but not in Precise 5.6 or Racy 5.5. In Slacko 5.5 retrovol comes up normally and allows me to make adjustments as needed. In Racy 5.5 or Precise 5.6 Retrovol come up with only one control, IEC958, and if I run ALSAmixer in a terminal it comes up with only <S/PDIF> and no others. If I place the cursor over the speaker in the system tray, the message says "volume: 65295%".

In desperation I tried copying the versions of retrovol, .retrovolrc, amixer, alsamixer, and alsamixer.bin from Slacko 5.5, but that made no difference whatsoever.

Also substituted the whole hda directory from the lib/modules.../ directory of Slacko 5.5, again with no difference at all.

Please help if you can.
bs