Can't speak for X20 (Pro) as i don't own one, but I do own an Xtreamer eXpress player based on the Realtek 1295 chipset, running Android 6 and having 2xUSB2.0 ports 1x USB3.0 and 1x USB3c. Using The USB3c port to connect with a PC host port the whole media player becomes a slave and all storage facilities connected to it can be addressed from the PC still acting as a media player normally. So also HDD's internal and on any other USB ports. I do expect Zidoo X20 (Pro) to work the same way.