I hated the fluttery background noises on the standard analogue audio jack on the RPi, so bought a Soubdblaster Play! for £20 from eBay.
/etc/modprobe.d/alsa-base.confand comment out the last line;
options snd-usb-audio index=-2
I actually commented out all the extra lines that ended -2 and now I have excellent quality audio. Really pleased. The RPiBox is complete. Wires for the GPIO and an improved larger screen have arrived. I just need to find a container.