Just connect this to a PMOD or Wing socket on the StickIt! board and your XuLA or XuLA2 can sample and output stereo audio signals! Here's a simple example of building a voice recorder using the AudioIO board:
As with the StickIt! board, we made the entire StickIt! Audio I/O module design open-source. All of it: bitstreams, schematic, PCB layout, documentation — everything!
When you order a StickIt! Audio I/O module, all you get is the board. That's it. The StickIt! Audio I/O module doesn't need any software itself. And the manual is online. As for the fancy box, well, sorry about that. Think of it as "saving the environment".
The StickIt! Audio I/O module manual will tell you how to install your board, and it shows a block diagram architecture and how the FPGA connects to the codec.
Ah, you mean how do you get signals into and out of the audio codec so the FPGA can process audio? Well, you could read the AK4656 codec datasheet and then implement the circuitry that configures the codec and serializes/deserializes the digitized signals. But why go to all that trouble when we already have a VHDL codec interface module for that and an example design that performs loopback from the stereo input to the output. With that, you should be able to get your own designs up and running in no time.