Not sure I follow your english (are you using a electronic translator?)
If an amplifier is not powerful enough for desired sound pressure level (SPL.) that sound quality will be reduced due to amplifier clipping.
However, it makes no sense to have too much power, because your speakers place a limit on maximum power. If you send excessively amplified signals to your speaker, you could damage them.
A very rough suggestion is to have an amplifier with twice the power as the speakers average power handling capacity (not peak.)