Limited soundstage between speakers

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.

OP here, thanks to suggestions offered here I tried the following:

1. move chair closer to speakers to form an equilateral triangle rather than isoceles and turn the speakers to straight ahead position. result- a wider soundstage!!!

But I cant leave well alone , so

2. toe the speakers in so that they point right at my head. Result- soundstage shrank towards center but gained depth and instruments &voices seemed more focused. Also noticed that some upper frequency hash was reduced which altered the tonal balance down a bit.

Which did I choose? I 'm not telling. Maybe I will go halfway...maybe not!

I always thought I had got my speaker placement right years ago but I have learned it pays to experiment