Pretty much words to live by.
In the words of my uncle, who is has a PHD in electronics - the input (aka microphone) and the output (aka speakers) make all the difference, what happens in between (aka DAC, pre-amp. power amp, etc.) is just not all that important and is so well understood that designing and building a good sounding one is pretty easy.
Now of course the above is an over simplification but the general idea is that the differences between two similar power amps will be much less audible than the differences between speakers. As Scott stated learn what’s important and proceed from there. Remember don’t sweat the small stuff.
