Several members of the kX Forum (mentioned below) here on Driverheaven have mapped the AD_EXT header that appears on most Audigy 2 series cards. Creative caused uproar in the modding and sound enthusiast communities by not publishing this pinout as they did for the AUD_EXT that exists on the old Live! and Audigy 1 series cards.

Thanks to forum members, Samir, Travelrec & Quennotte