this is the stuff that you as users could really help out on -- can you pin down precisely which version "sounds best," and prove (e.g. through null tests) which versions "don't work" because they sound different? that'll make it a lot easier for somebody who wants to help, but doesn't totally understand the historical context, to actually be helpful, without inadvertently making things worse.
right now, if some dev looks for "obxd source code," this is what they find: https://github.com/2DaT/Obxd
any idea if this is the right basis or not?
Yes, that seems the correct repository. Not sure if the old code is still there, and 2Dat seems to not be around anymore.
EDIT: The code there says "2DaT Better HQ mode" but is from 2014, so,. it must be from the version 1.1, which I believe is the one people refer when they say it's "better". Version 1.3 was compiled in 2016 <https://obxd.wordpress.com/category/news/> apparently from a different code ("Compiled using dozius fork and Soshi Studio GUI code
"), which doesn't seem to be there in the repository.
I still have the old version from 2014. Will try to bounce the same track with the two versions and see how different they are. A little busy right now but I will try to find the time up to the weekend.