I read your report on the Bigme 6 tablet.
I have found that using Koreader's ability to access an OPDS server to acquire books on demand is the simplest method. Calibre probably has a built-in OPDS server; if not, I'm sure there are third-party add-ons which read Calibre's database for that purpose.
@dashdsrdash Thanks! I will take a look. I appreciate your comment.