Uma maneira simples de ir é usar SoundFly . É feito exatamente para fazer o que você precisa (fluxo de áudio de um mac para outro).
A descrição do site:
Soundfly is a very little utility that just sends the audio of one Mac to another, using built-in Mac OS X Tiger technologies, and Soundflower.
It comes as a package containing an application that sends to audio over the network (Soundfly), and another that receives and plays the audio stream (Soundfly receiver). It works out of the box, but if you want further configuration, press ALT when launching either application: you'll be able to configure the Audio Units.