Can I use a 1/8 mini to RCA stereo connect to hook a PC to my stereo without damaging my Pre-amp?

After discovering Pandora and a few other internet stations, I set up a PC in my livingroom via wireless but with crappy PC speakers. I would like to run it thru my main system.

If this is not the way to do this, can someone recomend the correct way please?

TIA

Hyfi