Cross-talk and distortion, chief soundstage contributors...

With respect to amp, there are some merits in term of reducing cross-talk improving soundstage. Everything else being equal, I found that dual monoblock amps tend to have a more stable soundstage and focus. Intuitively, the less interference between the leff-right channel will improve the soundstage focus.

And of course having a well treated room will improve the soundstage as well. Likewise, better DAC, better cables, and so on will help as well.

As for cross-talk, there is more than just left-right channel.  There are cross-talks between the woofer and tweeter as well.  That's why bi-amp will eliminate the woofer-tweeter cross-talk which will in turn improving the soundstage and image focus.

listening99 OP
The "bleeding" of information from one channel to the other, is what I'm seeking to understand - how does this impact sound-stage?

The more you bleed left and right towards mono, the better the central image becomes, and the worse the image either side of center l & r and out side the speakers image becomes.
Vinyl is classic at giving a great central image at barely 30db of channel separation at 1khz in the midrange, but it's bass is almost mono, and it's treble isn't that much better.
Here is a expensive Lyra phono cartridge channel separation graph.
https://ibb.co/3Y9jM2W

I did an experiment for an audience on the output of a cd player to bleed the both channels down to 30db max, with a switchable circuit, and everyone preferred it playing old Beatles etc etc. Because it gave more richness to the mix, even though it was almost mono'ized and only had a central image. 

Cheers George

       

I am not of the opinion that the room accounts for the majority of the sound stage. It may be one component but that is only part of the equation.

Right. Soundstaging is almost entirely having the speakers precisely symmetrical and in phase. Everything else makes a difference. But none of it matters if the speakers are cockeyed and out of phase. Anyone doesn't get that flunks Audio 101. 

Now, this seems significant:

"The more you bleed left and right towards mono, the better the central image becomes, and the worse the image either side of center l & r and out side the speakers image becomes. "


Is this measured? Are we measuring this? What is the measurement? Is it articulated as a norm, in amp descriptions? 

Is this measured? Are we measuring this? What is the measurement?

You can simply do it yourself without any measuring gear, put a 10kohm pot between L and R channels on the output of your source, and get some one to slowly reduced it till it shorts L and R together, while your listening.
That’s basically what I did in the demo above but with a fixed resistance to reduce the cdp to 30db channel separation.

Now if you devise a circuit in a box for the cd output to mimic the separation curve of the Lyra cartridge https://ibb.co/3Y9jM2W , then your early ping pong cd’s will sound better like vinyl can do to them. I’ve already named it, and called it "The Digital Vinylizer"

Cheers George