To me, one of the most important subjective measure of a system is how it sounds at low volume. As a system improves, one can enjoy the sound at lower and lower volume levels--it still sounds vibrant and rich and seems to fill the entire listening room. High efficiency systems, particularly horn systems seem to do this better than other kinds of speakers. That might explain why Japanese audiophiles have huge horn systems in their tiny apartment rooms (being culturally polite, they would not play the system so loud as to disturb neighbors). It is, to me, wrong headed to seek a large horn system because that size suggests high volume capability--that may be the case, but, I still prefer horns that sing at quite low volume. I have recently heard multi-way systems built around a wide-range driver (e.g., Cube Audio Nenuphar Basis) and even some single-driver systems that pull this off successfully (e.g., Charney Audio Companion).
Turn down the Volume!
One topic that seems rarely discussed is volume. If you listen to mixing engineers, it’s their most feared aspect of how their work is measured, since it’s out of their control. This leads to things like loudness wars (assume the worst). As my system has improved, my main takeaway is I can be engaged with 60db peaks, where when I hear other systems you often have to turn it up to 90db peaks for it to sound decent. I’m pretty sure it all has to do with bass and room energy, but wonder if others have a similar experience. Side note that reviews or any subjective ‘better’ statements about gear rarely indicate how loud they are listening. since all we can perceive if volume it is puzzling. I will say if it sounds good with 110 db peaks then that is impressive.