Looking for wider soundstage

Open baffle speakers provide the greatest soundstage. Simple is best. 

@backdoor , I had a look at your pictures and I hate to bring you bad news but even with digital signal processing you are never going to get a decent image with your system as it is set up. It breaks almost every tenant you can imagine. It is fine for everyone's background music pleasure but that is about it. Your system needs a home that is more in keeping with it's intent. No amount of room treatment and expense is going to change this. Your next mission is to find a more appropriate home for it either in your house or eventually another if it is that important to you. 

dekay I’ll give that a shot. 
 

mijostyn that is bad news. 

mamba like spatial audio for example?

A sure way to increase your soundstage in an untreated room is to hang a soft blanket or even a sheet on the wall behind your speakers. Give this a try. If you hear a difference (you will) you can try the side walls at around the 90 deg angle between your seating position and speakers. 
 

hopefully you have a dedicated space and can do this. 
Give it a try and would like to hear back on your experience.