How do I stream Mac audio to Linux computer?

is there any way to stream audio from my Mac to my Linux computer (my av receiver is connected to that)?

I think VLC can stream the audio over the network - take a look at http://www.videolan.org/doc/streaming-howto/en/

If you don't want to pay money for AirFoil, you can use SoundFlower on the Mac and ESounD or PulseAudio's ESounD-compatible module on the Linux machine. This article explains how to do that.

You can use AirFoil ($25) for Mac to stream the sound to AirFoil Speakers for Linux (free).

This software works great.

This guide worked for me http://tdotc.wordpress.com/2012/05/28/sound-matters/

Summary:

Install Soundflower in your Mac.

# open network port 16002 to receive raw data for PulseAudio (in your receiver)
while true; do nc -l 16002 | pacat --latency-msec=1; done

# connect the audio input on OS X to a remote raw sound sink via esdrec and netcat (in your Mac)
esd -tcp -bind ::1 & sleep 2 && esdrec -s ::1 | nc <SERVER> 16002