Having fun trying to upgrade my speakers now (woo telephone tag!) but it should be fun - the room is 10'6" (3.2m) square with a 9' (2.74m) ceiling so with it being square it isn't the best.
My listening room is square too, you have my condolences. Square rooms can be tough, but manageable.
If it's a dedicated listening room, take a look at "Diagonal speaker placement". A diagonal speaker placement can break up some of the bass nodes that a square room tends to double up on. With your room almost being a cube, some of the bass modes are going to overlap and almost triple.
Consider listening nearfield, it takes most of the room problems out of the equation. Not all speakers lend themselves to nearfield listening, some speakers need a bit of space for the drivers to integrate.
Smaller speakers with a sub work really well in a square/small room, and give you a lot more flexibility. You can put the main speakers where they image and sound best, and the sub where it works best. Having the ability to adjust the sub independently from the mains really helps in the square/small room where bass can overpower the rest of the system. You can also DSP the sub if you'd like and leave the mains untouched. Some folks DSP the whole system, but I can't do that myself being an analog guy.
Bass traps and other room treatments can really help the square/small room too, but may not be possible if the room is not a dedicated listening room. It can also be expensive. GIK Acoustic sells finished products that cost less than the raw materials that I purchased when I had mine built back in the day.
I wouldn't mind trying the diagonal speaker placement, but it took me a long time to get my room sounding the way it is, and I don't want to screw it up.
