I would say that working with your SO is going to be critical here. I'm not an experienced audiophile but a room that large with concrete floors is bound to be a sonic challenge. Working with your SO to make the acoustic treatments things that she likes or will tolerate would be the way to go IMHO. I'm talking about rugs, heavy curtains, even decorative rugs hung on the walls.
Also, is there an option for creating a room within the room? Possibly using acoustic panels, furniture, etc to create a smaller more focused listening space? Or is the goal to fill the entire room with sound?
Also, is there an option for creating a room within the room? Possibly using acoustic panels, furniture, etc to create a smaller more focused listening space? Or is the goal to fill the entire room with sound?