Overview:He launched a host of today’s comedy superstars in the ‘90s on the HBO series Russell Simmons’ Def Comedy Jam. Now, Russell Simmons returns to the network for All Def Comedy, taped before a live audience Sept. 7 at the Avalon Theatre in Los Angeles. Hosted by Tony Rock, with DJ Drama, the uncensored special features stand-up performances in a variety of styles from up-and-coming comics, discovered at ADD’s weekly comedy showcase: Chris Powell, Zainab Johnson, Kevin Tate, and Robert Powell, as well as HBO’s Def Comedy Jam veteran Tony Roberts.