I've got a couple of instrumental tracks published which bring in royalties from time to time, and I earn a very small amount from online streaming. I'm currently building up a youtube channel for instrumental music which I'm hoping to monetise, but from actual songs - pretty much nowt (if you're registered with PRS you can claim on live performances of your own songs, works out about a fiver per gig if I remember correctly, haven't done it for a while)
tl;dr the only money worth earning is from 'synch' and getting instrumentals placed is a lot easier than getting songs placed.