Sirius XM Radio is lucky to be alive, and their growth hasn’t been cheap. But with 22.3 million subscribers, this is easily the largest music subscription service in the world.  In fact, they have roughly seven times the global subscriber base of Spotify, and Sirius chairman Mel Karmazin recently claimed to have more subscribers than all other music services combined.  The stats solidly back that claim.

Which means, Sirius knows something about curating content and monetizing the music consumer, despite all the criticism surrounding its programming decisions. “As we’ve said many times, business models matter,” Karmazin recently told a group of investors.  “Our business model is superior to that of terrestrial radio and the internet radio companies we compete with.”

“Also, at a time when more and more content is available and consumers continue to be time-constrained, there are still only 24 hours in a day. We believe curated content… is more important than ever and will be even more important in the future as even more content becomes available especially on the internet.”

Others are buying that philosophy, but not necessarily winning.  That includes Pandora, which recently pointed to a collection of ‘just’ 900,000, from roughly 90,000 artists (per the latest Wall Street disclosures), a number that has remained flat over the past few years.  This is a company that is putting little emphasis on growing its content collection: the iTunes Store has now boomed to 28 million songs; Pandora has about 3.2 percent of that.

But even iTunes-style collections mean little without the curation to manage it all.  It’s the reason why getting into the iTunes Store means nothing, while getting on the iTunes front door means everything.  And why Spotify’s OS fantasies involve curating apps, not just endless spreadsheets of music.  Because as much as the Spotify OS needs a massive and comprehensive catalog to make this work, the future may belong to those who effectively deliver less.