Jay Z re-launched Tidal with a lot of fanfare, but how well is his artist-owned streaming service doing so far? Just fine, if you ask the man himself. As part of a flurry of Twitter posts, Mr. Carter revealed that Tidal has "over 770,000" subscribers to date. He also scoffs at the idea that Tidal is solely about pampering wealthy artists who want a larger cut -- the rapper argues that Tidal's $60 million in equity value pales in comparison to the billions in musical net worth at rivals like iTunes and Spotify. Every artist on Tidal gets a 75 percent royalty rate, Jay Z says, not just those with a direct stake.