Fast post!
Strangly, Audacious just stopped working in this morning. The error message in console was something like this: Connection refused MADPlug-Message.
After some Googling I saw one people saying to verify output audio plugin.
I just go to Preferences > Audio > Plugin Output Audio and select ALSA Output Plugin, and everything back working.
Just trying to help other people with this problem that took me some minutes of my life. :)