Tidal has created a product that, in theory, woos artists by promising them that no one will listen to their music without paying for it in some way. And there's some justification for this thinking. Free streaming tiers, according to the Financial Times, brought US labels only $295 million in the US in 2014, compared with the $800 million created by paid subscriptions. That's a significant difference. But if Tidal really wanted to make the most money possible for its artists, it would charge somewhere around $6. According to research done by David Touve, an assistant profess...