Ummmm. It's hard to say how many iTunes users there are as you are kind of forced to subscribe just by using an iPhone. But it's a touch higher that 14000, a hundred million or so maybe. It's early days for Roon though, you've got to start somewhere!
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12