I was wondering if anyone knows how I should go about turning a normal RCA audio cable (left & right/red & yellow, whatever the right colors are) into a 1/4" jack. I'm guessing I'll need to use a stereo jack. Will I run into some sort of impedance issue?
Assuming you want a stereo signal just wire the sleeve of both RCA cables to the ground of the jack, then wire the signal / core of the RCA cables to the tip and ring connections of the jack for left and right. There won't be any impedance issues.
Everything you'll ever need to know about stereo jacks is here http://en.wikipedia.org/wiki/TRS_connector (http://en.wikipedia.org/wiki/TRS_connector)
Thanks Paul!