I have OBS studio and absolutely love the features.
But I can not seem to get it to broadcast/stream as clear an video stream as with Flash Media Encoder.
OBS has over 20 plugins to choose from, including one's that allow adding video files and any other media supported by VLC as a source, integrating Twich chat and switching scene depending on what window is in focus.
You can download a plugin called Direct Show Audio Source, but you're only given options to use audio inputs (mic, speakers, etc...).
You cannot simply select a wav or mp3 file to loop (going AFK or BRB for example).