you will need to be root for the following.
you have to edit your grub config. open
/etc/default/grub with your preferred text editor and look for
GRUB_CMDLINE_LINUX_DEFAULT and add
radeon.audio=1 to the end of it.
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.audio=1"
now save the file and run
you may also want to try to add this parameters at boot time to ensure it works before doing all of the above.
after you power on you may need to hold Shift to get the grub menu to appear after it appears press e and add
radeon.audio=1 to the end of a line similar to this
linux /boot/vmlinuz-2.6.38-8-server root=UUID=11111 ro quiet splash
linux /boot/vmlinuz-2.6.38-8-server root=UUID=11111 ro quiet splash radeon.audio=1
and press b to boot with the added parameter