In the beginning, singers were the ones belting out tunes, so they got all the credit. Then producers started getting props, even making debuts on artists' albums. Scott Storch, Pharrell, Cool and Dre — they've all become household names in the same way Christina Aguilera has. But there's one more player that makes a song a hit: the sound engineer, responsible for making the entire song come together, blending vocals and beats to get the perfect mix. Adrian "Drop" Santalla has tracked and mixed songs for artists like Fat Joe and Pitbull — in fact, he engineered Fat Joe's single "Lean Back" (produced by Storch), which was certified platinum. Not bad for a guy who started as a club bouncer, moved up to DJ, and then worked at a jingle house. Much like a high note, he slowly rose to the top, networking along the way and eventually working with big names at Circle House Studios. He eventually branched out on his own and launched UpsideDown Entertainment. Emilio Estefan recently asked him to mix tracks for Celine Dion, Carlos Santana, and Gloria Trevi.