Can somebody break it down in layman's terms for me?
And so one after another all he gets is a bunch of technical info. When the answer in layman's terms is actually in this case absolutely identical to the answer in technical terms: THERE IS NO ANSWER IN TECHNICAL TERMS!
Every single one of the supposed answers above, most of which sound sensible, a few of which maybe even are, nevertheless are easily proven to be nonsense. All these things are at best factors. But remember- correlation is not causation!
What happens, and OP it will really help if you can learn this one early, is someone hears an amp that sounds unusually powerful compared to its watt rating. So they look for reasons. Perfectly natural thing to do, look for reasons. Let's say they find the amp is capable of delivering a lot of current. Wow that must be the reason! Unfortunately, sorry, BS, which is demonstrated as easily as listening to another low current amp that seems to sound just as powerful, if not even more so.
The same can be done for every single one of the other technical reasons listed above, and a whole lot more we haven't yet gotten around to. Not to worry, the people incapable of noticing the request for layman's terms are equally incapable of putting a damper on their need to show off with word salad. Er, technobabble. Er I mean technical knowledge.
Oh and by the way, you can go through and replace "power" and watts with just about anything you want- liquid vs etched, 3D vs flat, dynamic vs damped, any and all of it. Sometimes there's really good causes you can point to. When faster diodes are swapped and the sound improves its fairly easy to point to the speed and recovery of the diode. Although even then its wrong to say the speed is the reason- because there are even faster diodes that sound worse, and maybe even slower ones that sound better.
Now take that one part, the lowly diode, multiply it by a thousand for all the parts in a component. Then multiply that by a hundred for all the different circuit topologies (the way the circuits are physically laid out) then multiply that by a handful more for the way the chassis and, well you get the idea. Or at least I hope you do. There's just way more variables involved than you can ever hope to understand, let alone boil down to one simple number. To then point to that number and say, "THIS is why!" Is simplistic and shortsided in the extreme.