multiple audio

Hi everyone, just wondering if something is possible please.

I have a PC with 2 DVI and HDMI, i am running my pc in one room with dual screen that is a dvi monitor and a hdmi tv on my desk and using the on board sound card over a 3.5mm jack for my sound and all working great.

would it be possible to ude the other dvi port to a DVI>HDMI cable to my main tv and use a S/PDIF to my amp as I have no HDMI ports left via my amp.

do i have to change sound each time or could i have it to auto use S/PDIF when on livingroom tv?

hope this makes sence.

thanks