I have Libreelec running on an old Zotac ZBOX Atom pc and would like to connect it to my new KEF LS50 Wireless speakers which have a USB DAC built in. I have plugged in the USB cable but the DAC does not show up in system settings under Audio devices. The speakers also support TosLink but I'm using toslink from my TV and would like to connect the Libre via USB. Any suggestions on how to get Libre to recognize the USB DAC?