Looking for wider soundstage

You need to be systematic with moving the speakers around or you’ll drive yourself crazy.

Go to YouTube and search on New Record Day LOTS.  He walks you through a method that’s simple and works.  Then you can tweak with room treatment and cables.

 I have an Yggy and integrated tube amp, open baffle speakers and I have a really big ss and great imaging.

@backdoor OP there is great information here and as many say here, Google is your friend. http://www.cardas.com/room_setup_main.php

More here. 

The Pros: Acoustic Sciences Corporation

Free advice & discussion:
https://www.gikacoustics.com/acoustic-advice/
https://www.acousticfields.com/acoustics-forum/
https://www.audioasylum.com/forums/rives/bbs.html

The speakers are too close to each other, The preamp I know and heard that produce wide or huge soundstage are Backert Tube preamps, I think  the Rhumba  is the one I heard from a friend system.

Try for a smaller triangle and remember, the triangle is just a starting place. My speakers are 8’ apart, center to center and my listening position is about 9’ from the speakers. Also, see what you can do about the couch. Most speakers need room all around them and close to the same amount for both.

BTW, I have the same doorway as you do, but I don’t have a door, so it’s sometimes very annoying. I bought one of those adjustable room dividers and hang a comforter on it when I want to be picky.

All the best.

JD