Even without knowing how to read or write music, and probably because of it, Roena knew how to surround himself with excellent musicians and arrangers. "Apollo Sound" featured musicians from the ensemble of Tito Puente, "Cortijo y Su Combo", "El Gran Combo" and "Los Sunsets", among others. Some of the well renowned arrangers and composers who nourished his repertoire were Mario Ortiz, Bobby Valentín, Elias Lopés, Luis “Perico” Ortiz and Papo Lucca. With "Apollo Sound", Roberto introduced a “new” sound to salsa music by utilizing two trumpets, a trombone and a saxophone, a combination he took from the influence of the wind section of the rock group Blood, Sweat and Tears (in honor of which his band recorded a successful version of “Spinning Wheel”).