some people have incompatible phones or media players - even some of the early iPods won't work. Believe it or not I've got (and occasionally use, because the sound is better) a first edition iPod and that doesn't run on usb at all. The only way to connect would be with the stereo jack.So what's the Aux socket for?
When I test drove the mini, I produced my nokia 1020 phone running on windows phone - i.e., neither apple os or android. The salesman said I'd need to use the stereo jack to connect. Turned it on, paired it - works a treat without any cables.