That's correct, but it's actually a bit more nuanced than certain people like to portray it as. Sound reproduction doesn't use a constant amount of power--it's peaking and dropping all the time. So the theory goes (not sure if I subscribe to it or not) that the more you have in reserve, the easier it is to achieve those peaks.
So the theory is that a 1" garden hose would fill a 10 Gallon bucket faster from a 1,000 gallon tank than from a 100 gallon tank? Ok I guess you could make a case for higher water pressure generated from the 1,000 gallon tank. But thinking way back to basic physics, flow in an electrical circuit is governed by resistance not wattage.
