Like live unamplified music.
and it takes your whole audio system to achieve something close to live unamplified music, not just speakers.
Speaking of the ’perfect speaker’ apparently has a tendency to negate it as a speaker - for a good reason, it seems. And yet what’s the point of that when what we’re left with is always a setup of speakers for re-production? What’s perfect anyway - "perfect" within the limits of tech, design, acoustics and our abilities into implementation? Convenience, even?! Why not dream on within that realm and those conditions and make perfect a little less so, and yet pushing against those boundaries (not least convenience and dogma), just to make it a bit more attainable and something we actually want to aspire to. Within those limitations there’s ample room to strive pretty high, but maybe the real, implicit reason for making perfect unattainable is so many of us don’t have to deal with the mere effort of getting there - or, that is, certainly closer to "perfect."
It certainly and very typically takes much more bass capacity, properly implemented, to get to that place where bass just happens in the room; wholly effortlessly, smoothly, mostly unrestricted in frequency range, and at any desired SPL. That one has to experience to understand, and yet getting there is inconvenient because the practical measures necessitated would challenge interior decoration and spousal approval.
An interesting exercise, and confusing when the adjectives start flying with no description of the meaning of the words. First, a speaker should do no harm. In other words, it shouldn't change the sound (especially instruments), in any way, that was captured on the recording. 1) A flat frequency response is the first requirement (and easier said than done for most speaker designers). 2) Near zero relative phase response (how the drivers relate to one another in terms of phase). This will permit a proper leading-edge dynamic. It will allow a speaker to disappear as a source of the sound. 3) With those two goals intact, the speaker must be able to faithfully track the dynamics of the recording – both micro and macro dynamics (don't underestimate the importance of faithfully resolving micro dynamics). 4) Details: the elimination of anything that veils the sound on the recording. And the ability to represent all of the ambience (reverb) the recording has on offer. If all done well, the speaker will enlist your attention and draw you into the music's beauty and intent.