After everything is said and done, it will still remain that no one will definitely be able to prove anything to everybody.
Even within digital amps, you have debates regarding class D, class T, ICE, digital switching power supply only, all-digital path, partial digital, different sampling frequencies, PWM vs bitstream, etc, etc. Not to mention the new "Class A/AB digital" about to be brought to market by Odyssey Audio.
Within solid state, you got the hotly debated mosfet vs. Bipolar, Jfet, classA, AB, B, sliding bias, blackgate vs the rest, differential, balanced, bigger caps better vs. "distributed node" small caps, etc.
Not to neglect tubes. Push-pull vs SET, 300B vs 2A3/45, triode vs. Ultralinear, solid-state rectification vs tube rectification, battery bias, best driver/phase-splitter, DRD, Ultrapath, then there's Tom Evans stuff. Not to mention the Allen Wright tube amps that are doing some interesting things.
I've probably heard both great and bad sounding amp in each technology niche, so what's the point. Pretty much any of the above can be made to sound great if one knows what he's doing. Then there's the grand question of the listener's "tastes." The trick is to correctly identify your own tastes and biases, figure out an amp that will synergize with the rest of your system, then pick a price point you can live with. Some can live with $40K price point, whereas some will only feel good with the Panasonic.