Plausibly confirming a previously speculated meeting prior to the GRAMMYs, Madonna, Beyonce, Rihanna, Nicki Minaj, Calvin Harris, Jack White, Kanye West, Jason Aldean, Daft Punk, and Coldpay's Chris Martin were featured in Jay Z's Tidal teaser video. Other artists like Usher, Alicia Keys, and Arcade Fire appeared via Skype. Jay...

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