I had a problem I solved and I would like to know why it worked.

I finally decided to transition to a 64-bit install (AMD64).
(same machine, just reinstalling as a 64-bit kernel starting w/ a Debian squeeze netinstall image)

My audio chipset is nvidia MCP61, and it was working perfectly under a 32-bit kernel
(I did the transition because a poorly-written system backup script (my fault) hosed /usr, /bin, and /sbin)

When everything was up and running:
*: KDE4 only recognized the output device as ALC1200 Analog
*: kmix only had a single channel(master)
*: alsamixergui did recognize all the channels
*: some games (sauerbraten, for example) had no sound in KDE4.
*: some games (warzone2100, for example) did have sound in KDE4.
*: the games that had no sound in KDE4 did have sound in fluxbox.

I removed the following packages (some of which I had installed to try to get audio working properly):

pulseaudio-esound-compat
pulseaudio-module-x11
kde-config-phonon-xine
phonon-backend-gstreamer
phonon-backend-vlc
pulseaudio
pulseaudio-util

Now, all is happy-happy-joy-joy again.
KDE4 is now recognizing all the output devices (ALC1200 Analog, ALC1200 Digital, and Jack Audio Connection Kit), kmix shows all the channels of my chipset, and audio works like it should.

WHY???

That I got audio to work is of secondary importance to me. Knowing why is always my primary concern.

I would guess that the problem was pulseaudio.
Is this a good guess?
Does pulseaudio suck that much?

Can't say for sure as you have installed then uninstalled several *unrelated* packages. One thing I can add that might help is that I went back to Gnome on Ubuntu simply because KDE was way too finicky about having "permission" to use the sound card on both 32 and 64-bit systems. Sometimes I would get an error about permission, and sometimes it just wouldn't work.

Cheers

Pulseaudio came along with the initial install.
The only extraneous packages I had installed were the alternate phonon backends. I had initially mentioned them because I had uninstalled/purged them in the same command as with the pulseaudio-related packages.
Be that as it may, it seems to me that, most likely, the pulseaudio-related packages I had uninstalled were responsible for my KDE audio problems.

My original query, however, remains:

Was this a pulseaudio issue?