The simplest fix is to throw down an area rug to absorb some of the reflected sound. Next is to reposition the speakers and where you sit. Portable/temporary room acoustic panels may be the best answer. The bass panels and mid/hi absorbers are not hard to make if you have time and skills and will save you lots of $$$$$$$.
Large room fix
What is the best amp and speaker combo for a room with all hard surfaces. I didn't really know how bad my system sounded until I hooked up my older gear into the short term rented home I am in now. Long story short......my pre upgraded (older) equipment I have playing now in a "normal" sized room with wall to wall carpeting sounds way better then my "upgraded" gear in my home with hard floors, large windows and tall ceilings. Do I simply need more power and bigger woofers?