Colin, if you really want to understand what's going on, you must expand your vocabulary to include "decibels". This is how "loudness", or acoustic energy, is expressed and when electrical energy/power (watts) is converted to acoustic power (decibels) all new rules apply. It's not a 1 to1 relationship as would seem logical.
For instance, an apparent doubling of loudness requires about ten times the watts. Merely doubling the watts results in a barely audible three decibels of loudness increase.
If you really want to learn more,
this link does a fairly good job of tying the three together, but you've got to try to grasp it.
Once you've got that down,
this next linkwill put those pesky decibels into real-world situations where you might be better able to grasp it better.