I’m a little late to the party this year but the 2013 SXSW Music Showcase Torrent is up for your downloading pleasure. I try to post a link to the torrent every year but Greg Hewgill’s website has torrents for SXSW years going all the way back to 2005. This year the torrent contains 999 files totaling 6.13 GB of music from bands playing at this years South By Southwest Music & Media Conference. Keep a close eye on Greg’s website because he will most likely be putting up a second torrent with more bands in early March.
If you’re not interested in downloading/seeding but still want to listen to the music you might want to try this (currently not working) SXSW FM page.