CSCore
An advanced audio library, written in C#. Provides tons of features
... codecs, effects and much more! CSCore is based on a very extensible architecture that allows you to make it fit to your needs without any major effort. You can build music players, voice chats, audio recorders and so on! Supported platforms, Windows only, Linux and mac experimental. Optimized performance though the usage of CLI instructions provided by a custom post compiler.