several thoughts i would add to (or reinforce) in this nice discussion
1 - agree with many who have said that live performances come in all shapes, sizes, volume levels - listening to a solo jazz piano without amplification at the village vanguard is a totally different musical experience than hearing beyonce at coachella - also, even at a village vanguard kenny barron solo piano gig, if you sit front row, or to the rear, it will sound very different, at the rear you hear the ’room’ alot more than the piano direct
2 - leaving aside amplified live concerts, even some unamplified instruments like drums trumpet or sax played in domestic environment would be ear piercingly loud - so a critical differentiator of the op’s two notions of sweet vs live is the volume setting of the music being played
3 - as relating to hifi systems, to me a really good system should succeed at both delivering smooth soothing beautiful music most of the time, as well as some (not all) of the excitement and visceral nature of a live performance - but often not simultaneously -- per the point above, the volume level is the primary variable, and choice of recording/its quality is the major second variable
4 - in my own experience, really good systems can play loudly with little strain, less evident harshness to the listener, as harmful distortion artifacts are managed to very low levels by good gear selection and optimized room acoustics - thus better systems can be listened to longer at higher volumes before fatigue is felt
5 - some systems, some speakers do better at low volumes, some others come to life and present the beauty, detail, impact and body of live music at a certain (higher) volume level - this occurs as various transducers exhibit different frequency and phase responses at different db/power levels
6 - finally, we as listeners have vastly different tastes, perceptions, hearing, references to what sounds smooth and sweet, and what sound ’live’
