Would I be able to wire 3 audio sources (one to each card) and avoid customers talking to each other on hold? A few cheap fm radios wouldnt bother me.

Could you go into a little more detail on the pin 3 and 18? Should I wire into the back of the slot? or if i wanted it to look like crap can I just stuff the wire in the proper position in the slot when I put the card in?

Love the help thanks guys!