Thanks to the internet I have been able to set up my pi as an airplay receiver using shairport and a cheap external DAC off Ebay.
What I'd like to do next is to configure the pi to take an audio source (using an external ADC - like the PCM 2900) and send it to an airplay receiver. This way I can use a music keyboard wirelessly.
From what I understand I think it should be possible to use pulseaudio to do this but am not sure how to set this up. I'm comfortable with putting together the ADC but linux isn't one of my strong suits. Any help would be much appreciated!