7S Cameron
1000+ Head-Fier
Well, there is the complete list here:
http://git.rockbox.org/?p=rockbox.git;a=summary
With every new entry there is a new build. Look for iBasso in the title of the change to filter out the ones that are affecting our player a lot.
And there is the general major changes list, where only the important commits are listed and explained quickly:
http://www.rockbox.org/wiki/MajorChanges
So, every time there is an update to Rockbox as a whole the DX50 version will be updated as well?