I just installed an auxilary input for an mp3 player. Everything works and I didn't run into any problems. However, now I notice a small huming noise even when the radio is turned off! It's very faint but when I have the windows up I can make it out. I wouldn't think there would be a noise when the radio is off, but apparently there is. Installing the aux input was rather simple, so I sure hope I didn't ruin anything. Anyone know what this might be? Also, did I void my warranty by installing this cable myself? Thanks in advance!