WARNING! In my opinion the hardware drivers of the Cirrus Logic Audio Card never left an experimental state and the card is not usable in production. It's an odyssey to put it into operation on a Raspberry Pi 2. Here's a summary about the current state, pointing to useful resources and providing a tutorial to get the card up and running with Debian Jessie.
As a response to my lastest article about Streaming audio with MPD and Icecast2 on Raspberry Pi, I was asked for some ideas about live streaming. I took the chance to plug in an usb audio device with microphone to RasPi and tried to get it working.