I just discovered this and tested it by formatting my drive then loading everything back from C6.
1 . Go to Sound Manager (Function + Sound)
2. Tap the first trig two times and all the trigs will light up.
3. Press the right arrow and choose ‘Select All’
4. you will get a message ‘#### sounds selected’
5. Scroll to bottom of same menu and choose send sysex. (make sure C6 is recieving before you do this)
6. Save your file. your +Drive sound library is now backed up.
strange that this is not in the manual or update notes.