one aux input, two sources?

I'm swapping out a factory CD player in a 2001 Tahoe. The stereo has an aux input adapter wired up to it the the cassete player/cd changer port on the back of the radio. Its a PAC 2 input adapter with a DVD player on one input and an mp3 player on the other. Theres a dash mounted toggle switch that lets you flip back and forth between the DVD and mp3 player. Now I'm trying to install an Alpine cd player with one aux input. How do I get both sources into this one input? Is it ok to put an RCA "Y" splitter and just have them both connected and only use one at a time? Or will that cause problems or noise? Can I split the RCA cables and wire them up to relays to toggle back and forth with a switch like the PAC adapter? Gimme some ideas guys....

Anybody????????

you shouldn't have a problem with using the splitter just be sure not to run both at the same time.