Hi
@Jack Simmons - I use Distrokid, it works very similar to Amuse and CD Baby.
As Vicky says it's almost worthless if you don't make an effort and market your stuff (I'm not on Facebook, Twitter etc.), but that's where I'm not concerned about that side of it, in fact I'm very interested in how organic the increase in plays etc is, and how different elements affect the plays.
For example I put Korean titles in my sound cloud songs to see if that made any impact on the Korean market and yes it does (a tiny tiny impact), and as a by product of the Korean titles, I now have a few more Japanese listeners, which may be Koreans living in Japan)