Jay Z aims to topple Spotify with music streaming service Tidal

Musicians including Beyoncé and Madonna show support for rapper as he overhauls service designed to make more money for artists
He has sold 100m records, founded a business empire worth upwards of $520m (£350m) and married Beyoncé. Now, Jay Z, backed by a roll call of A-list friends, is fronting the relaunch of a music streaming website heralded as the first real challenger to Spotify.Kanye West, Rihanna, Coldplay, Madonna, Alicia Keys, Beyoncé and more threw their weight be