By all means, fill us in.
In your example above, take the pre/pro from your pre/pro + amp setup and switch between the power amplifier and the receiver as an amplifier, level match between the two and then run a double blind test that does not push one or the other outside of their comfort zone. Then see if you can reliably identify which is which - that is the premise of the argument. Nothing more nothing less.
The fact the you believe that a consumer grade, mass market 7 channel receiver (amp section only) cannot possibly be distinguished from, say, a hi-end 7 channel stand alone power amp speaks volumes for your lack of practical experience. If power amps are nothing more than a commodity, then you owe it to yourself to fill in every engineer in the business nevermind speaker designers and professional critics. Clearly, vibration control has no impact on sound quality. Power supplies? Nope. Class A, class B, Class A/B? Whatever. Fully balanced? Only words. Use of negative feedback? Pfffftt. IT ALL SOUNDS THE SAME.
Tell me, when was it that power amps reached this point where they all began to sound the same?