1) you can get audio "splitters" that will do that...but not sure where to find one
2) you can use the digital out on one of your cd-rom drives if your soundcard has both a digital AND an analog in
3) you can enable "digital audio extraction" from within windows on most newer systems and you can stream music over the IDE channel...which effectively eliminates the need for an audi cable altogether. option is in cd-rom properties (right click on cd-rom in device manager)