Everybody has this problem, because every room has this problem, because sound waves interact with each other and with the room to reinforce or cancel and this happens in all three dimensions not only the two everyone talks about.
The most efficient/productive approach is to try a lot of different speaker/listener locations. Listen for the best balance of imaging and smooth frequency response. But do not put too much emphasis on really low bass, because this is as you are beginning to realize a problem that cannot be solved. Not with just two speakers, anyway.
So you get the ballpark locations first. Then dial it in with absolute precise symmetry for the best imaging.
Finally, add four subs. These can be just about anything. They can go just about anywhere. The key is four, and in different locations, as the only solution to the room mode problem is lots of different sources.
Do a search for Swarm or distributed bass array.
The most efficient/productive approach is to try a lot of different speaker/listener locations. Listen for the best balance of imaging and smooth frequency response. But do not put too much emphasis on really low bass, because this is as you are beginning to realize a problem that cannot be solved. Not with just two speakers, anyway.
So you get the ballpark locations first. Then dial it in with absolute precise symmetry for the best imaging.
Finally, add four subs. These can be just about anything. They can go just about anywhere. The key is four, and in different locations, as the only solution to the room mode problem is lots of different sources.
Do a search for Swarm or distributed bass array.