Technically they need an implant in their head - the amp is something that is attached afterwards, and can be swapped out. Then there are armors that sync with the external amp to further boost power...our Biotic Armor would do that, even better.
Then we could also go one step further with it and have the armour tuned to a single user, to boost their abilities and increase the cool down rate even more.
Unless arc reactors were severely nerfed while I wasn't looking, our power generation can only be desrcibed as sufficient at this point. One industrial scale reactor produces around as much power as the whole planetary interior heat flux (that is, heat from the planetary core). At this point the only question is how to move that power. Something I think being addressed by advanced materials.
The ones we have only pump out 50TW, we didn't have the materials to make one that pumps out 150TW.
Technically, we should have enough money coming in a couple of quarters to research a second generation Industial Arc Reactor,
but considering the other stuff that keep on happening, it might get put off....
Then of course, it becomes a question of 'what do we use the entire energy output of a planet for'?