Play with some room treatments. I have 2CE Sigs, and that helped out the soundstage and imaging a lot, even on recordings that were mastered in an extreme R&L way, as was unfortunately typical for some early stereo recordings, such as your old Brubeck. Even more extreme are early Charlie Parker recordings, John Coltrane, Miles, or the worst, the early Beatles recordings. Some of this extreme separation you just have to live with. So yes, as already stated, much is how the music was recorded and mastered. Newer music typically does not have the same issue as older recordings, and the center image is almost always ‘spot on’. But you want, if at all possible, the sound eminating from ‘the stage’ the same way the musicians were in the recording (unfortunately much modern music was never recorded this way in the first place, as a ‘live performance’, as it was all recorded at different times). The ‘live stage’ effect is the ideal so the instruments don’t sound like they are coming directly from the speaker face, but more side to side. A good recording helps, and more poorly recordings can be helped with speaker placement and acoustical treatments. The 2CE’s are very finicky about placement to achieve this goal. Been there, done that.
Begin playing with some acoustical treatment. I find in my case, the 2CE’s are benefited more from diffusion vs absorption, have both, but that may just be my room. You can do this cheaply by getting some foam or rigid insulation and tape panels of it temporarily in various locations to find what may work best in your room. There is basic info available to this as well all over the internet or on YouTube. As far as diffusion panels, that is tougher to to get something cheap to temporarily use. I actually found some sculpted 18”x18” architectural ‘Tiles’, taped them together behind, and then applied them to my walls with 2 sided foam 3M ‘tape’.
