Though we've been through this before I think it's always good to hit the refresh button from time to time.
Loudspeakers are an obedient lot. They respond in exactly the same way to whomever their taskmaster might be. Which means it doesn't matter how big the amplifier feeding that loudspeaker is. 10 Watts delivered from a 500 Watt amplifier is, as far as your loudspeaker is concerned, the same as 10 Watts delivered from a 50 Watt amplifier.
Put another way, imagine you're serving dinner to friends. On the menu tonight is a tasty soup. Each guest has the same size soup bowl. As you ladle out each portion into their bowl, it matters not the size of the cauldron you're pulling from. As long as there is sufficient soup in the kettle to fill each bowl, no one will overeat (or go hungry).
Loudspeakers demand only as much as they need to move their drivers for a given loudness and frequency. Once an amplifier has satisfied that demand, having a surplus of power available is more bragging rights than practical.
