You may have to turn the phone output volume up to match the F6B FM internal levels. My Owner's Manual (2016) says this. I had to set my iPod volume higher than I usually listen with earbuds (for just regular listening at home, not while riding). And I was not using the Aux lead in the left fairing cubby, I'm using the USB in the left saddlebag. The Aux lead in the cubby definitely will be affected by the output level of any device connected there.