I had serious issues with my soundstage and imaging.
But it appears to be caused by hash or noise in my high treble.
These issues were solved by the addition of what are known as Zobel networks plugged into the binding posts of my speakers. In my case, those are the treble ones of the two pair. There is a fellow on AG who has built these: Deulund-Mundorf Speaker Purifiers. I think these can be built using those caps and resistors with a heat sink. Although the component values are custom made for the Ohm rating of your speakers. They do not interfere with the built in speaker crossovers since they only effect HF 12K Hz and above.
I had thought that my speaker placement or room were to blame. Not the case!
Now after about 150 hours of break in for the caps, imaging is pinpoint and the soundstage is wide and deep. I guess it’s like getting a pair of highly upgraded tweeters. It is clear that the former HFs were “dirty”. To “purify” is the key.