These tools are useful for hacking around with codecs and uncovering some mixing capabilities. http://www.alsa-project.org/main/index.php/HDA_Analyzer http://git.alsa-project.org/?p=alsa.git;a=tree;f=hda-analyzer;h=7cd9faff91499dbdb181799e5673834fe3a443ca;hb=HEAD
some more info https://bbs.archlinux.org/viewtopic.php?id=147208
Something more actual. It's currently at pygtk2, there's WIP gtk3 port. https://github.com/kosiu/alsa/tree/gtk3 https://github.com/alsa-project/alsa-utils/issues/134 From first look - hda-analyzer is not only tool in that project (full package could have name alsa-misc).