will there be an echo in my livingroom when I replace the carpet floor in to a wooden floor??

or does this give a negative effect

could do - hard, "reflective" surfaces are always more troubelsome than soft, "absorbant" surfaces in a listening environment.

Yes, but from experience, even a few small rugs and a bit of furniture make a big difference. If I take my Persian rug out, the sound is a lot worse.

does the alt lenses minimize this effect

To an extent but clearly the sound still bounces off walls and thence to the floor etc.

so the conclusion is that carpet is still the best floor for loudspeakers