"It's a reaction to what passes as soul music," says ?uestlove
Day-long Philly fest features full 'Wu Massacre' set, the Clipse and Mayer Hawthorne
Philly crew debuts new track from ninth album 'How I Got Over'
"I was trying to make something that was sample-able like a '70s soul record," ?uestlove says
The Roots drummer's favorite all-star jams and musical celebrity slams