Here’s a relevant anecdote:

http://money.cnn.com/2008/07/15/technology/emusic.fortune/?postversion=2008071614 :

…
Jesse McCann, digital operations manager for Allegro Media Group, a music distribution company in Portland, Ore., says his company makes about the same amount of money selling songs on eMusic as it does on iTunes: “I’d say our eMusic check is about the same as our iTunes check.”
…