There are free utilities to combine MP3 files into one long MP3 file - MergeMP3, maybe? I know I’ve used something like that before when ripping CDs to combine single tracks into one MP3 file per CD, but one MP3 file per book could be done also. It wouldn’t be my preference, but that might work for your situation. I’m sure there would be benefits to having the book as an AA file instead of MP3, but I don’t know of any converter.
Flashing the firmware - just read up on it. Know the risks & rewards and weigh them. I don’t use Rockbox because of the possible risk of it disabling Digital Rights Management - if I didn’t rely so heavily on DRM for downloaded library books, I’d be trying Rockbox. I’ve toyed with the idea of “sacrificing” one of my old Clips to Rockbox, just to see if it really does disable DRM.
