Uneven soundstage help, please.

There’s several EQs for sale on Audiogon. If you don’t have tape monitor buttons you can hook up an EQ between your favorite source and the integrated pre amp. 

I will never live without this Chase Remote Line Controller RLC-1.

I have used one for many years in main system, now also in my office system, and a spare on the shelf downstairs.

Absolutely quiet, Signal to noise is 105db, it just does it’s job.

Open Box, seller takes returns:

https://www.ebay.com/itm/Chase-Technologies-RLC-1-Remote-Line-Controller-RLC1-Upgrade-Any-Stereo-NOS...

Adjust everything from your listening position.

1. remote volume, a wonderful thing
2. remote balance. this will solve your room’s imbalance, and even if your room and listening position was perfect, sometimes certain tracks benefit from a speck of balance. It is surprising how much benefit can come from a small balance adjustment
3. loudness compensation. essentially bass boost at low volumes (boosts highs also), to automatically adjust for our irregular hearing at low volumes.

https://en.wikipedia.org/wiki/Equal-loudness_contour

it’s a good thing when used properly, keeps music involving at low levels, rather than just background music.

4. tone controls. I don’t use them, but you might try, it cannot hurt. It remembers your adjustments which is great. On/off by remote, no controls on the unit. Unplug, plug back in, everything back to factory settings if you cannot remember where you left it for instance. I have easily accessible on/off switch for that as my memory sucks.
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Toe In. When I want a wider center for 2 people, I adjust my toe in, aim the left speaker at the right position, aim the right speaker at the left person. That works like this: you are closer to one speaker, but you get direct sound from the one facing you from the other side. It balances out, a wider center image for 2.

For now, I found a way to widen the distance between the speakers. Barring kids and pets visiting--unlikely these days--they should be okay/safe from harm. Then I matched the distance from the speakers to the listening post as best I could. By necessity, one speaker could be exactly right, but the predominant-sounding side had to be 6 inches farther. It's not worth explaining why beyond fixed wood stove, side wall, no wall at all, intervening door, etc.
I figured what the hell, let's try it. So I experimented with toe-in next. Lots of toe-in gave me a strong, equally heard center but a narrow soundstage and a loss of airiness that I didn't care for. I switched to no toe-in, which hadn't worked previously, and lo and behold,I heard a distinct improvement in soundstage with no loss in any other dept. I had to wriggle my seating around a bit to make it work.
I'm happy for now. Someday I'll see how much better my system can sound by trying some of the things posters have suggested. Thanks to all. I really appreciate your help. I wish I could be more helpful to others here, but I guess I find a way to do it in non-audiophile realms.

Elliot, when I read about the remote controller, I don't see anything about balance. Otherwise, I'm intrigued.

Elliot. Never mind. I found a close-up of the remote and there was the balance control, allaying my insecurity. Do you know this will work with my system? I'd like to get one if it does.
Details: Deezer and Qobuz to Mac to Audioengine D2 DAC via USB to wireless D2 receiver to MFA308 integrated amp via RCA to ATCs. Where would it go in that chain? Do I have the right inputs, etc? Remember, I'm an idiot who needs basic instruction.