suggestions for hooking digital speakers to two sound cards.

[hitbyambulance]

Situation: i have two sound devices in my computer - the nForce SoundStorm 5.1 and the Turtle Beach Santa Cruz. the TBSC is faaaar superior for music-listening purposes, but it can't handle EAX 2.0 too great in games (and can't do 3.0/4.0 at all). i have Cambridge Soundworks FPS2000 4.1 speakers with a minijack digital connector (the yellow one). currently these speakers are plugged into the TBSC - the plug doesn't fit into the SoundStorm (which has a female RCA digital connector and for which i've never been able to find a compatible adaptor, for some reason), and so i had to use analog hookups when i used it before (front and rear speakers).

since I have both sound systems enabled in WinXP, I would like to have both hooked up to the speakers. right now, the SoundStorm is hooked up only to a headset/mic and used only for telephony purposes - i would now like to use it for gameplaying, and be able to switch (via the sound control panel) sound sources depending on what i'm using it for... and when i want to listen to CDs, i'd switch back to the TBSC.

ideas on how to go about doing this with digital connections? i want to make sure any adaptors/splitter cables used will work properly.