1. User manual, Quick start guide, DAC driver download link of K15

User manual/Quick start guide download link

https://forum.fiio.com/note/showNoteContent.do?id=202105201631166296804&tid=17

FiiO USB DAC driver download

https://forum.fiio.com/note/showNoteContent.do?id=202105191527366657910&tid=17

FiiO Control App download

Android version:https://forum.fiio.com/note/showNoteContent.do?id=202105071628040377809&tid=17

iOS version: You could search and download 'FiiO Control' from the APP store.