My new DAB radio has a USB charging socket but did not come with a USB lead. Can I buy a USB cable which has 2 male ends and use that to power the radio by plugging one end into a USB wall socket and other into the radios charging USB socket ? I don't really understand what they mean by charging USB socket, charge what, it doesn't have a battery in it. The manual is very basic and does not mention that, the radio came with a removable mains lead. Many thanks for any answers.