You need this drivers to get audio from X-Fi, ALSA doesn’t have drivers, but Creative have supplied a data sheet to developers so development work has started.
Status: Front Panel doesn’t work with Creative official drivers (at least as today March 30, 2009)
There is a compatibility issue with Ubuntu 8.04
Installation process: (thanks to NullHead on ubuntuforums)
1) Check if you have the minimal compiling tools to build your driver:
(you can check it first with aptitude show build-essential or … linux-headers-… if you don’t have that install it)
aptitude install build-essential (if you have trouble with the ”, just check your version with uname -r)
aptitude install linux-headers-'uname -r'
2) Download the official driver with the link provided before or with:
3) On a clean folder unpack the contents of the gzipped tar:
tar -xf XFiDrv_Linux_Public_US_1.00.tar.gz
4) Get into the directory
5) Compile and install
Then check if the drivers are in your settings (for gnome go to System->Preferences->Sound
6) Finally you have to restart
http://ubuntuforums.org/showthread.php?t=870001 (the original article that works, than you very much NullHead)