One link catched my eye here: "The evolution of a data structure – the WAVEFORMAT" https://www.assembla.com/spaces/portaudio/wiki/Win32AudioBackgroundInfo
Maybe it is of some use for Wine developers too:) Some URLs need adjustment, though.
Eg. Creative Labs description of Vista audio architecture changed to: http://forums.creative.com/showthread.php?t=302341
S.