How do I use the current sound out as an audio input in Quartz Composer?

Question

If I want to build a spectrum visualizer of what's currently playing on my speakers (not the line in) what do I do?

Answer 1

Download and install Wiretap Anywhere from Ambrosia Software.

Wiretap allows you to take any audio outputs from applications and route them to a virtual audio input which you can use in Quartz Composer, or any other OS X application that uses a hardware input.