my panasonic just has one set of audio plugs. not sure if they are input or outputare you sure you have the speakers plugged into the audio outputs, not inputs on your Panasonic?
Yeah I have one of those cables, however it loses the 5:1 surround soundIf it's not working they're probably inputs. Do you have a Headphone (3.5mm) jack on your TV? If so you can always get a cable from monoprice.com 3.5mm to RCA
http://www.monoprice.com/Product?c_id=102&cp_id=10218&cs_id=1021817&p_id=9768&seq=1&format=2
the speakers are meant to be for computers, it comes with a USB connection. However there is a control pod with a headphone and audio output connectionTrue. That said, I'm not familiar with your speakers or TV. How many inputs does your speaker system have?