Tube Amps For Vandersteen 5a's? How Much Power Is Really Needed?

I just made a deal for a mint condition pair of these. I've long wanted a really good pair of Vandersteens but didn't have the budget to play in that space. I've read a number of discussions here, and otherwise, talking about this, though they were somewhat older. Despite the fact that the low end in these speakers is internally amplified, and one would think even SET amps, or certainly just about any good push pull tube amp would power these superbly, people generally seem to be throwing a LOT of power at them. Am I missing something? 

Any input, expertise, or thoughts would be appreciated. Thanks.