Some of my Kindle books have forms to fill in so I converted to pdf so I can read them on the DPT-S1.
See this thread in the Calibre|Convert forum:
https://www.mobileread.com/forums/sho....php?p=3363161
I repeat the settings on the Calibre convert dialog box here:
Azw3 to pdf
Look&Feel
Base Font Size: 15.0pt
FontSizeKey: 10.0, 11.0, 12.0, 12.0, 13.5, 17.0, 20.0, 22.0, 24.0
PageSetup:
OutputProfile: Generic e-ink HD
InputProfile: DefaultInputProfile