Short story:
Use the Portaudio .dll from this folder if you want the same Portaudio version
which comes with butt-0.1.21 and/or you need WASAPI or dsound support.

Long story:
The Portaudio .dll in this folder is the same version that was delivered with
butt-0.1.21. Unfortunately, users encountered audio issues if they do very long
broadcasting sessions with this version. Therefore I decided to pack the latest stable version of
portaudio to this newer version of butt.
However, if you want to use the same Portaudio version that came with butt-0.1.21,
you can download the .dll from this folder to your butt installation directory.

You find the installation directory by typing %LOCALAPPDATA% into your file browser address line.