This is a fantastic how-to. I followed this exactly and now my RPi has sound output. More importantly between these instructions and moving the WiPi off of the RPi usb port and onto the usb ports on the lapdock has made Scratch stable and seemingly reliable. Every now and then Scratch freezes even though the cpu meter is not pegging but if you wait it comes back. This wouldn't be important but a 12 year old boy's instruction in the black arts of computer science is at stake here. Maybe I should drop the whole RPi into a small fishtank filled with kerosene or mineral oil and bang the clock up to 1.5GHz (somebody must have tried whole immersion liquid cooling, a'la Cray).