Using Airfoil With Audio Hijack Pro or Nicecast
You may wish to use Airfoil in conjunction with Audio Hijack Pro or Nicecast. Airfoil can pull audio from these applications, but by default they don't actually output any audio. Thus when Audio Hijack Pro or Nicecast is set as the Airfoil's audio source, Airfoil simply sits waiting for audio and never receiving any.

Using Airfoil With Audio Hijack Pro Or Nicecast
Airfoil can be made to broadcast the audio passing through Audio Hijack Pro or Nicecast with just a bit of setup. Follow along with these steps, which use Audio Hijack Pro as an example:
1) Set Audio Hijack Pro as the Audio Source in Airfoil, and click Transmit.
2) Set up Audio Hijack Pro to grab and adjust the audio you want to transmit through Airfoil.
3) Play the audio in the original source application set in Audio Hijack Pro.
4) Set up the Auxiliary Device Output Effect in the active Audio Hijack Pro session, at the end of your audio chain
5) Mute AH Pro's output with the "Mute" button. The audio will now play in the original source, flow through AH Pro, be pulled in by Airfoil and transmitted.
These same instructions will work for Nicecast as well.