Have you guys checked out AudioEngine in 3.7rc0?
On Win32, OpenAL is implemented, setVolume per sound effect is implemented, and it supports playing MP3 via mpg123.
Strangely, there seems to be issues with wav files, or at least the format of wav that I tried to play caused a crash. Will need to look into that further.
Have yet to try to play OGG files.
WinRT AudioEngine uses XAudio2, but also supports MP3 now.
Is there a license issue regarding playing MP3 files on Windows?