I may be able to shed some light on this. During the dyn outage I really wanted to keep listening to soundcloud, so I spent a bit digging up the hostenames/IPs to dump in /etc/hosts. I found that they were fetching data from two different hostnames, cf-media.sndcdn.com and ec-media.sndcdn.com which I'm guessing stand for cloudfront and edgecast. Never dug deep enough to figure out how they sharded the data, and I'm not even sure both were used for songs (maybe one was pictures, one was tracks) but I seem to recall needing both to play all songs consistently.
