Afrojack is used to manipulating technology to create loud noises in front of groups of large people. The Dutch DJ, born Nick van de Wall, earned $18 million last year–landing at No. 7 on FORBES’ Electronic Cash Kings list–mostly from fees gleaned from cranking up the bass at nightclubs around the world. Earlier this week, however, he made a sound he’d never made before: Afrojack rang the closing bell at the Nasdaq’s Times Square market site. The occasion was the initial public offering of SFX Entertainment, the electronic dance music promoter launched by live music mogul Robert F.X. Sillerman.