I was looking for some good code to steal, and I ran across
QasMixer (
http://xwmw.org/qasmixer/). It is an ALSA mixer
application very much like the CLI `alsamixer`.
My favorite feature is that it allows you to browse and
manipulate /all/ of the cards on your machine at the same
time. (In contrast, with alsamixer you have to start
another process with something like `-c 1` for your other
sound cards.)
QasMixer used to be called Alsamixer-Qt4. I have absolutely
no affiliation with QasMixer, I just think it's a very
useful and well-done application.
-gabriel