The arrow down or up is for next or previous song? Does it also work with the screen off? How is the battery life? Does it last up to 12 hours as advertised? Also, how does it compare to the Fiio X1 sound wise? I've had my Fiio X1 for a few years now and my only gripe with it is the scrolling wheel that just never worked. It is still usable but navigating with buttons were never comfortable or easy.