For Tidal Launch, Jay Z Summons ‘The Avengers Of Music’

One by one, they took their places next to each other: the leading lady, the masked man, a duo in metallic suits–eighteen in all–and, in the middle, dressed in all black, their leader.

This was not a sneak peek ofThe Avengers: Age of Ultron. Rather, it was the launch of Tidal, the streaming service Jay Z recently purchased for some $56 million and is rapidly attempting to shape into a direct competitor to Spotify, Rdio and the like.

Alicia Keys strode to the stage, followed by a genre-spannin...