speakers in a bad room

i will get a rug in front of the speakers, but is that enough ?

Dude, sound waves are sound waves. Pull out your physics book. Get a thick rug, fill a book shelf at the back of the room (with books), and buy some acoustical treatments to dampen the initial reflection points!

I think I agree with Jeff. Rugs and tapestries will offer greater sonic improvements than expensive speakers.

18 X 24 is a bit small. However ages ago I had a system, (mono because stereo was not yet invented) in the concrete cellar of a New York City house. When I played dixieland jazz it was great, because the jazz dives that I visited at the time were all in cellars.

I agree that the reflections will be wicked, wicked good perhaps! To get the full effect get a speaker with a honky horn midrange.

Today my system is much more refined, and I listen to a lot of classical chamber music. But when I play jazz, I'm not sure it has quite the impact of that first system long ago.

The room will need some form of acoustical treatment, but I suggest you mate that with a speaker that is designed with narrow dispersion characteristics which you can set up for near field listening. This will probably limit you to single driver or two way speakers.