why do expensive amplifiers produce a better soundstage

In my experience, different DAC's made for better soundstage.  And later, on a particular DAC, upgrading the capacitors in the signal path to films increased the clarity and soundstage / imaging.

I'd say if you changed ower amps and noticed better soundstage, then the input stage of said amplifier was just better.

@lanx0003 

"Share it. This is what the forum is all about.  Maybe you could give AI and everyone here a good lessen what actual soundstage should feel like."

I was simply commenting if the OP had listened to multiple examples at various price points over time, he’d find inexpensive amps and integrateds that image extremely well. I’ve had all kinds of integrated amps HH Scott, Jolida, Rega, McIntosh and currently, Luxman, Icon Audio, Naim and just arrived today an inexpensive Rotel a8 that I can’t wait to set up with an inexpensive SUT I bought to use with it’s phono stage and the other great source components I have listed in my profile. I also have two rather nice sets of speakers to try with it in addition to my main ones I use with my tube amps (profile). 

I think I can say I put my money where my mouth is as you infer. So, what’s your experience?

@emergingsoul 

I am among those who have changed system components and room acoustics and noticed improved imaging with the same recordings. 

@faustuss  My experience in soundstage was previously articulated here:
https://forum.audiogon.com/discussions/walk-in-soundstage?highlight=walk-in%2Bsoundstage

Since then, I have upgraded several front-end components: the streamer to Volumio Rivo Plus ($1,650), the I²S cable to Veritas Optimus, and the XLR interconnect to Veritas Magnus. As a result, the soundstage has become even more immersive in all dimensions. Compared to before—when the soundstage was wide but low and relatively flat with the budgetary streamer/dac—the presentation today is distinctly three-dimensional.  Notably, I have not changed my amplifier (Parasound A23, $650 used) or speakers (Wharfedale Lintons, $1,500 new). I also reintroduced the Schiit Saga 2 ($280) into the chain. The DAC currently used is the Harmony Micro DAC ($950).

I list prices intentionally to highlight that the amplifier and preamp are the least expensive components in the system. Yet, they have proven fully capable of preserving and restoring the soundstage information already present in the recordings when paired with the right front-end components. In contrast, my previous digital sources—streamers and DACs—effectively collapsed depth and masked layering, resulting in poor separation and diminished spatial cues.

To be clear, I am not suggesting that the amplifier at the back end of the chain does not matter for soundstage presentation. Everything matters—the entire chain, setup, and room—when it comes to preserving spatial information embedded in recordings. However, many affordable amplifiers today already offer competent specifications (sustainable current delivery, damping factor, slew rate, and low noise/distortion) that are important for accurate soundstage reproduction.

In my experience, this means that amplification has increasingly become a necessary condition rather than a sufficient one, whereas the front-end components—particularly digital sources—have a disproportionate impact on whether spatial cues such as depth, layering, and image separation survive the signal path at all. At least in my system, and based on my listening, the primary bottleneck was clearly in the digital front end, not the amplifier.

"What the heck does soundstage mean?"

for me, higher resolution sound system as a whole, produces better soundstage.. meaning I can hear every instrument etc. more clearly.