Track & Mix downloads.
Che Armstrong commented
If this means what I think it means, then it sounds like a great idea. Why not build a Proton download portal, and allow users buy direct. This would cut out the middle man and (I expect) generate higher royalties because of this. Heck, you could even follow Beatport's streaming idea and allow users to do that. :D
Having bought Proton's first compilation, I'd definitely love to see more of this.