I am using my PPCPE on a motorcycle and listen to mp3/GPS and talk on the phone with T-Mobile handsfree set. I want to hear signals from a radar detector as well. Will I damage any device or distort sound from mp3 if I just solder cables from the two sound sources? Radar uses 3.5mm mono jack... Would adding resistor on the detector side help a little? I would appreciate any advice. Thanks.