PSpectrum v2 is finally ready.
I'm sure I'll add many more interesting features in the future, but for now I'm happy with it.
PSpectrum allows programs that can not access the audio devices of your system, to access the audio data of the system.
I mainly use it for my PSpectrum Audio Visualizer for Powercord.
To capture the system audio I use the Bass library made by un4seen.