After some failures (Jack was not running) I was able to use the Raspberry Pi as a audio-to-RTP bridge. A complete setup guide can be found on this page.
This project was started to transport the sound from my turntable to the loudspeakers without visible cables. Our flat already had ethernet in all necessary places, therefore the idea was to transport audio over ethernet.
I didn’t want to use large and expensive hardware for this experiment. Therefore the Raspberry Pi looked like the ideal hardware. It runs Linux and has integrated sound, network and USB. Unfortunately the sound hardware is unusable, because it does not feature an analog input. Therefore an additional sound card is needed. My choice was the Behringer UControl 202. It used the Texas Instruments PCM2902 chips that is well known, well-supported and good-sounding.
Stay tuned for more informations on this project.