Limited soundstage between speakers

The best way to investigate this is buy a couple of good absorptive panels (a pair of the ATS 2 inch deep, 24x36 panels off Amazon), hang them on the wall at the first reflection points and see what happens. I’m betting your imaging improves dramatically. It’s not an expensive experiment and can be reversed very easily.

Brad

Buy Magneplaners.  Have an expert set them up IN YOUR ROOM.

If they do not give you what you are seeking, I have no further suggestions other than change your hardware or sources.

Cheers!

I hope you find a solution with toe in. I have Spendor speakers also. Big SP100's. And I am obsessed with getting imaging outside of the side of the speakers. When set up just right (as they are presently, with toe in directly at my ears) they not only throw images outside of the sides of the speakers but almost wrap around my listening chair. Of course this requires a recording that will do this. For example,Blue Note Jazz records never do this in my system. But try Kruder & Dorfmeister - DJ-Kicks - High Noon found on Youtube. Even on my Bose computer speakers the imaging is way outside the speakers. 

Just read an interesting about extreme toe in, I tried it; aimed the left channel to the extreme right of my listening area and vice versa. You can use a laser measuring device to really dial it in. I'm still on the fence about it; the only problem I "see' doing this is that I'll have to get a bigger chair/couch😁

The Zobel networks are the simple and super effective fix. I could have never imagined. But now every record is a concert with the musicians standing realistically across a vivid soundstage. On AG they are called Deulund-Mundorf Ultra Speaker Purifiers.