Polarity of Sansa m240?

I just bought a dc port for my car, but in order for me to connect it to my m240 properly, the manual asks for me to determine my audio device’s polarity first (negative or positive).  I did some research online and there’s supposed to be symbols that look like: (o ----(-) or(+) - something like that -  but I don’t see it anywhere on the player. 

Does anyone know if it’s positive or negative?

Thanks in advanced!

are you trying to play music through the speakers? Why not just use an FM transmitter.

I can’t locate anything on the polarity.

Try writing support@sandisk.com

You can sign up for an Ebox for support

Support Info Click Here

Let us know what you find out.