Have you tried putting in four or five large leafy plastic plants? Scatter a few of them around the room, particularly along the wall behind and between the speakers. The leaves act as small diffusers. Works well for me. And it's 1/10th the price of audio diffusers and sound absorption accessories.
Speakers or room
I have a very lively room. Tile floors, large window and open area. If you clap there is a loud echo. Furniture is limited. I set up Kef LS50w and the sound is recessed not forward. The room is 26 x13 and even up close it doesn't sound good. Is it the room? What should I do ? Wife acceptance factor comes into play.