This amplifier power and volume calculator will help you understand that doubling the amplifier power does not double the sound pressure level (SPL) or the perceived loudness.
You can also use this amplifier power and volume calculator to see what effect a bigger amplifier may or may not have on the perceived volume.
Amplifier Power and Volume Calculator
For an explanation of these results, see the article on Double Amplifier Power does not Double the Volume.
For those who need to know, the formulas used for these calculations are: