It *seems* to me like your workflow is the issue.
correct me if I’m wrong, but it sounds as if you’re assuming that a given mic at a given distance will work perfectly for all cabs and that switching the cab with your preferred mic should give you the best result. I think that’s the wrong approach since every cab/mic combination is different. And cabs sound great with a ribbon mic, others not.
So I think it’s wiser/more to the point to audition the cabs (as spec’ed by line 6), and when you hear something your like, or in the ballpark, then you can play with the mic and placement.