simple setup for playback two separate audio outputs from different channels?

[chueh]

I have a MacBook 12" which only comes with ONE built-in headphone output. I am wondering if I could just add an external sound card or any setup to play back a song at the same time from a DAW to different audio outputs from designated/different channels? Thanks

 

[mjbphotos]

'Channels'? Are you looking to create different headphone mixes while recording?

 

[chueh]

No, the song is already recorded, but I need to perform the piano live with the orchestral part which is created from a DAW. Since from time to time, the orchestral part is silent, while I am performing the solo, I need to keep the timing accurately in order to sync with the orchestral part when it's in certain measures. I need a set of headphones for myself while performing to hear the modified metronome clicks and some notes for reminders, while the audience can only hear the orchestral part from the speakers. It's the same song but with variations in different channels. I need to separate the channels for the headphones and the speakers.