Well, I have two suggestions but I’m afraid you (meaning your wife) ain’t gonna much like either one, but they’re free/cheap. The first thing I’d do is try pulling your speakers 6’ out from the wall just to see what happens (I recommend trying this when the wife is MIA). I have a feeling that alone might do a lot of what you’re looking for. If it works you can install these Herbies gliders in place of spikes, and in addition to making it easy to move speakers out and back they may also give you sonic improvements as well. I had to do this before I got a dedicated listening room and was well worth the effort. Eventually I just started leaving the speakers out the the wife just got used to the look and stopped saying anything about it.
https://herbiesaudiolab.com/products/threaded-stud-glider
Next, you could try some diffusers like these behind your speakers, and in addition to possibly yielding imaging improvements they might let you leave the balance in the middle rather than having to put the balance control in the circuit — I know my sound quality suffered when I used my preamp’s balanced control. Plus, I think these look pretty cool…
https://www.theabsolutesound.com/articles/2022-golden-ear-gik-acoustics-gotham-n23-5-quadratic-diffusers/
The good news is, as audio gear goes, these are relatively cheap and may be very effective. The downside is implementing either may result in your wife throwing something at your head. Maybe use some of the $$$ you woulda spent on an amp on a nice necklace or something to help cushion the blow. Just a couple things to ponder FWIW, and best of luck!