The British pair manage two of 2014's biggest-selling artists -- One Direction and 5 Seconds of Summer, who moved 1.4 million and 1.1 million albums and 7.9 million and 3.3 million digital songs in the United States alone, respectively, according to Nielsen Music. Both industry vets -- who together have 75 years of experience in the business, in touring, publishing, marketing and A&R -- have run major labels. Yet for Griffiths, it all comes back to the live performance. "Whether it's the first show I put on at school or looking out at Giants Stadium when One Direction and 5SOS did three nights there last summer, the buzz of seeing it all come together is still the same."
HARDEST BUSINESS LESSON LEARNED: "Oh, that's easy. Don't tell your boss he's a f---ing idiot." -- Griffiths