There's a recent A'gon thread that addressed a similar topic at great length. You can read it
here. In that thread I wrote...
"...to my ears, the three principal characteristics that limit how real most systems sounds are: Dynamic range, spatial cues, and harmonic content. My suspicion is that dynamic range, spatial cues, and harmonic content are themselves chiefly limited by recordings, rooms, and equipment, respectively. Dynamic range is limited both by the inherent informational limits of recording media and by the elective use of compression during mixing. Spatial cues are limited by acoustically under-treated rooms, which obscure spatial cues, or by acoustically over-treated rooms, which limit the directionality of spatial cues. And harmonic content is limited by various kinds of equipment-induced distortion, whether harmonic distortion, IMD, TIM, etc.. This is of course an oversimplification, but the general point is that, IMO, the chief factors that limit how real most systems sound are dynamic range, spatial cues, and harmonic content (probably in that order)."
Mrdecibel - Those observations seem relevant to your OP. In direct answer to your question...
How "live" do you think your system really is?
My answer is: On excellent small scale recordings, my system is somewhat close, which is to say, I *very* occasionally hear something on my system that strikes me as indistinguishable from real. On large scale music, however, my system is nowhere close to the real thing.
If people have systems that sound indistinguishable from real with large scale music, I envy them.
Bryon