XM Audio from the 496 was best wired into the music input of the Sigtronics through a variable resistor. Radio Shack has them quite inexpensively for a STEREO (2 channel) potentiometer.
I presume the 696 is similar.
On the 496 there was "strong opportunity for error" as there was an "audio out" wire that you did NOT want to use. Audio needed to come from the 1/8th inch stereo jack.