Mac Miller: The Billboard Cover Story
Mac Miller Drops Free 'Macadelic' Mixtape

But among Miller's listeners back then were Grinberg and Pitt. Miller befriended them and he hustled relentlessly, with people like Pittsburgh producers E. Dan and Big Jerm, who were working with Khalifa. In 2009, a year after his first show, the buzz that Miller and then-manager Quentin "Q" Cuff (who freelanced for local hip-hop magazine Jenesis and knew how to connect the right dots) had been building in the Pittsburgh area sparked Grinberg and Pitt's serious attention. Combine those DIY efforts with a handful of pending courtships from other labels, not to mention Miller's imminent plans to drop his breakout set, "K.I.D.S.," and, Pitt says, the rapper forced Grinberg and Pitt's hands.

"People started talking about him [early last year], which caught our attention," he recalls. "'K.I.D.S.' was [Miller's] best work so far, and he really wanted to work with us."

Miller still has pretty much zero radio rotation. He's occasionally heard on local mixshows, on stations like WUSL (Power 99) Philadelphia and WQHT (Hot 97) and WWPR (Power 105.1) New York, and played by SiriusXM DJs like Static Selektah, DJ Green Lantern and Tony Touch. He's released the EP On and On and Beyond, which has sold 54,000 copies since its March 29 release, according to Nielsen SoundScan. There have been singles with impressive sales-among them "Donald Trump" (404,000), "Knock Knock" (316,000) and "Frick Park Market" (150,000)-on the label in the past year, as well as free mixtapes like his "Best Day Ever" (released in the spring) and "K.I.D.S.," which promptly came out after his signing to Rostrum last summer.

For "Blue Slide Park," out Nov. 8, there isn't a major co-distribution deal in place, as Rostrum has done in the past, most notably in 2005 for Khalifa, who signed deals with Warner Bros. and Atlantic Records in 2007 and 2009, respectively. But Miller boasts a whopping 176 million views on his YouTube channel, where polished, energetic videos for tracks like "Donald Trump" draw attention even from the Donald himself, who recorded a 40-second video response of his own, calling Miller "the next