Siman later served as senior vice president of Sony Music-Nashville, where he signed the Dixie Chicks to their initial deal as well as writers Marcus Hummon One of These Days (Marcus Hummon Song) and David Vincent Williams ("I'm Movin' On"). He would later serve as attorney for the Dixie Chicks. While at Sony, he was appointed to the Academy of Country Music board of directors and would go on to serve as President and Chairman of the Board. Additionally, he served on the Country Music Association board where he spearheaded the board decision to establish CMA Music Fest after the board had voted to end Fan Fair.