Try the clap test, walk around the room and clap your hands real hard, do you hear an echo? If yes, think about what happens to sound coming from your speakers. The direct sound from the speaker arrives at your ears different from the reflections from your wall and floor and ceiling.
If you don't want to get into bass traps and acoustic panels, at least throw some nice carpet throw rugs or something on the floor between you and the front speakers.
Anything, you can add to break up the reflections a bit will help with the overall sound.
I have pics on my website of the panels I've built for HT1 and HT2.
