Thanks for the replies!!!
The living room is opened with the dining room, so it's large (18'x20' for the living room only).
It's not a cinema room and we never listen to TV, Movies or music too loud)... but I just want a decent sound!
I bought this home theater new a few years ago but was in the basement and we never really used it. Now I realize it is a poor quality.
The speakers are Denon (SC-R391 in back, SC-F391 in front, SC-C391 center and DSW-391 for the sub).
All wires are good and I tried different sound settings. The sound is great for an action scene... but the following scene where actors talk (or listening to a talk show) will have poor sound, like if there was echo or people talking in a can!
Thanks again for your answers, I appreciate it!