hooked up the mp3 player today in the frunk,there is a usb cord and a 3.5 cord.The mp3 player plugs into the 3.5 cord,you cannot use the usb plug to charge it while playing,the usb plug is for the phone and bluetooth,I would think that if there is a 3.5 plug for playing there should be a usb for charging,oh wait there are 2 charge plugs,in the rear of the trunk. Seems so simple to me but hay,i am just into my music.Had the music turned up all the way and at 75 cant hear crap.So will do what i have done before,Install a head unit,make some speaker pods for 6.5 speaker front and rear,and then I will be rockin.Not complaining,just sayin