linux and audio after su'ing to different user

I have a 3rd party program that I run under a specially created user in linux (Ubuntu). I've noticed that it can't connect to ALSA and also gives me the following error:

2011/01/12 20:52:38开发者_运维问答 [ao:3] Opening Advanced Linux Sound Architecture (ALSA) output (2 channels)... No protocol specified xcb_connection_has_error() returned true

The program in question is liquidsoap, and is a headless (no gui) audio streaming program/

However, when I try running the program under the default user account, everything works fine. My question is, is this a permissions problem? And if so, where would I solve this?

try

$ sudo adduser <user> audio
$ sudo adduser <user> pulse
$ sudo adduser <user> pulse-access