tl;dr sheet music on iPad. There's a $20 billion music buyer market in the US and $80bn overseas, but most of that money is spent on instruments. The market segments Chromatik is chasing are a) classical musicians, of whom there are few (but enough) and b) high school band musicians, of whom there are plenty. The crossover with computer-based musicians is almost non-existent. Outside of the classical sphere hardly any working musicians use sheet music.