What makes instrument immediacy, -separation & -bo

Having recently progressed through stages of mods to a BAT VK tube amp, I've heard the qualities of which you speak all improve together in the same amplifier driving the same speakers. It's particularly interesting to me that soundstage size & depth-of-field are as much a product of improvements to the amp's electronics as they are a result of speaker placement or room effects. Deep-hall effects are revealed in the far corners, but the performance also moves forward of the speakers toward the listener. The amp improves in its ability to retain accurate frequency balance & dynamics at reduced volume. Finally, the qualities of grainlessness, smoothness, warmth & relaxation, are in no way unreconciled to improvements in treble resolution & air, and punch. Great dynamics is the quality that binds everything together. It fits the instrument's body within the boundary of its image & delivers impact approaching live performance. You sense that it's the intruments that are jumping, not the amplifier. The acid test for live performance is bass control. Almost all amps fail to communicate accurate texture in the bass region.

I would add that the same improvements to circuits that reveal low-level information required for spacial cues, also reveal textural details & corrected pitch & timbre in voices & instruments. So it's not just about uncovering deep background. This is why that piano sounds so natural when heard from the adjacent room. This type of improvement has nothing to do with room treatments or reflected sound.

However, such improvements in electronics (at least when driving my Merlin or Wilson speakers) do nothing to enlarge the sweet spot. If anything, the effect is lens-like in the sense that movements in and out of the sweet spot are more easily detected & create dramatic shifts in L/R imaging.

Shadorne, I'm not convinced that recording in an actual performance hall is necessary to create a sensation of live performance in playback.

In any case, there are certainly many recordings that are made live-in-the-studio & combine a sense of room acoustics with correct placement of instruments & good separation. All the CIMP direct to two-track jazz disks are recorded with musicians in one room & no close miking or compression. Or a Ry Cooder ensemble outing like "Buena Vista Social Club." The excitement of Derek & the Dominoes "Layla" is partly due to the (mostly) live-in-the-studio recording with leaks across multiple microphones. Though the sound of this session is sometimes maligned, the original LP is actually a pretty good test LP. On a good system you can hear both good instrumental separation and fidelity, as well as a very active room that communicates the energy & dynamics of a live performance in spades. In a larger setting, MTV Unplugged gigs like Alice in Chains, Nirvana, and Pearl Jam at Benaroya Hall manage to be remarkably good at separation, fidelity, and you-are-there in a real performance space.

But even many recordings that don't have technically "correct" instrument separation and obvious room effects (such as ECM or Chesky jazz CDs with the drum kit spread all over the soundstage from left to right and other instruments layered on top or behind), the sound can be uncannily real in terms of fidelity, separation, & sense of real life.

But a bad playback system deadens that sense of living, breathing performance in every case.

Interesting points about reverberant fields in the original performance, the relative contribution of first arrival vs. reflected sound, and hearing realistic piano sounds in the next room. However, after fixing the variables of room treatment & speaker position, I've observed huge improvements in realism & spacial representation after modifying the circuits of high-quality commerical separates. Even quite expensive stock electronics are compromised & fail to communicate the low-level information necessary for realism & spacial cues. Room variables can only contribute modestly toward remedying such inherent shortcomings. The good news is that the gap between built-to-cost and near SOTA-equipment can often be closed in the aftermarket with light modifications.