I have connected a soundblaster mp3+ via usb to my ps3. it shows up in the sound-config applet and plays stereo just fine using the various test commands.

I was using Fedora 7, (which has alsa ver. 1.0.14), and had been compiling bleeding edge kernels, with the sound modules set up as modules.

The stereo part was almost plug-and-play, except that to install the USB, I did have to enable the "CONFIG_USB_EHCI_SPLIT_ISO (Experimental) " option in the kernel.

I gave up trying to configure the SPDIF to do surround sound (long story). GT