Looking for the next level in imaging...

Two specific ways to increase soundstage depth, as you seek.  First, increasing the distance of your speakers from the front wall can have a huge impact.  If this works in your room, it would be my first move.  Second, consider a tube based amplifier.  My McIntosh C22/MC275 do a much better job with depth than comparable solid state amps. 

Also, are you working with a dealer or other professional?  As noted above, this is a really complex process.  An hour or two from an experienced person might be well worth the expense

As @patrickdowns touched upon briefly with instrument placement I don’t see why so many here look for which instrument is where in a song. Are there more genres than classical orchestras that play music in such a way?  Does most everyone here listen only to classical music? Surely it doesn’t matter as much in a studio where everyone is standing? And the sound is in the hands of the engineers anyway. With classical music being a small part of the world of music I fail to see the importance of what instrument is where in a song. I have some classical music in my Qobuz library and it sounds good but I really just want the music I like to listen to to sound great and not worry about what is where. Am I missing something to listen for that would improve my listening experience ? I listen to 60s 70s 80s 90s etc. 

Have you tried BACCH, with the newly added room correction feature built in?  I believe that it can be a game changer for any system, no matter how expensive.  It is priced well below your proposed budget and has a reasonable return policy if you are not happy with it.

@polkalover

What happens when you remove the table sitting between the listener and the speakers? I recognize that this is not a spouse approved move, but it might provide a no cost improvement.  As mentioned above in reference to another poster, it is always helpful if we could see your components on your profile.  I don’t have the expertise to analyze your component mix, but many here do.

@bigtwin Wow!  Someone else knows about Opus 3, Test Record 1 - Depth of Image!  It has been my standard since first hearing it while demoing Mission 770's back in 1981.  The two standout cuts for me for depth are "Tiden Bara Gor" and "Polka from the Bolt".  In the showroom the depth portrayed by the Missions was deep and wide and I bought them on the spot.  Unfortunately, I was never able to reproduce that level of imaging at home until 2016, when I got a pair of Martin Logan ESLs.