On my system the difference is absolutely staggering. Not too many recordings sound horrible, but man the really great recordings are just mind boggling. I will be finishing a room for listening in the near future. Very anxious to see what proper setup and treatments can do for those less than stellar recordings.
How much is about the recording
For myself, I'm comfortable in knowing I have arrived. At my own personal audio joy through years of empirical data and some engineering knowledge and application. I just wonder how many like minded individuals find as much joy in finding the best recordings vs the perceived next best gear. Peace.