Agree; its the variability in electrical supply, panels, switches, current. Its also the reverberation of plaster, the vagaries of wooden and or leaded windows, etc. Having lived in an old timer with these issues, then building out my own space, the consistency of flooring, walls and electrical supply can be significant factors. Let alone the variables in those apartments which seems to be popular amongst reviewers (!)I agree, but what is wrong with old buildings? The construction is often much better than new buildings, especially for sound.