I just wish I could get a handle on that nebulous amp attribute that allows a 100W amp to shine over a 200W ampOr, vice-versa of course. Very robust power supply /rectification, matched output devices, carefully chosen components, application of feedback, etc, etc. So many things that are NOT visible to the naked eye...
BTW, regarding spl's, in the near field, ribbons lose about 3db per doubling of distance vs 6db for cones. A difference of 20db spl b/ween sound 1 and sound 2 means 2 is ten times louder than one. To achieve an extra 20 db difference you need an extra 100W of electrical energy. Accordingly, 250W should achieve ~24db. If you want 40db headroom (ie 100 times louder) you need 10.000W. Classical music often has 30db differences. Under normal conditions, that would require 1000W over the reference low passage.
Depressing isn't it:)
Fortunately, we usually listen at low spls and consume milliwatts of our amp's power, so there is headroom enough even with a 50-100W amp -- or less -- for the forte.