Need to get sounds from 2 macs to 1 set of JBL Creature speakers?

Okay, So im getting a second mac for christmas and I intend on setting it up right next to my mini. I currently have a set of JBL creature II speakers hooked up to the mini. My question is, If i were to get a set of headphone splitters, since my input on the sub for the jbl speakers is an auxillary, could i run an auxillary cord from each mac, and get sound form both of them? Would it limit sound to one speaker, or would both work with all the speakers.