If only this was the case. There would be no need to purchase any amp over $1000. Anyone who has been messing around with audio for a while knows, almost everything makes a difference.
As someone who repairs vintage amps, they all sound different. Say I have 2 identical amps. I recap one with brand X caps, the other with brand Y caps. Guess what? They will sound different! Even changing a couple electrolyte caps, to a film caps will change how the amp sounds.
Yes, every amp will sound different. You can even put a scope on the output and they have different sign waves.
Anyone with a Class D amp knows you can change the sound of the amp with just swapping out the power supply. People who have measured the output of the amps with different power supplies have recorded differences.
These are facts based with measuring before and after, plus using ears that can also measure the difference. Think is someone can't understand measurements, or have good ears, then more power to them, as they can get cheap $100 class d amps and be happy.

