How much does power amplifier really matter comparing to other hi-fi components?

i enjoyed reading all the answer's and I am sure the fellow that asked about the percentage question is more confused now then before. I have been in audio since I was 12( now 69} and in MY experience it’s just trial and error. I will say the room is very important, cuz no matter how much you spend, you always “Hear” your room, for good or bad. Overtime, my  taste in sound signature changed from bright and loud to warm and laidback. I just did a lot of reading and the consensus for my taste was I needed a Pass Labs amp. Bought what I could afford (Pass 60) and later on got the Pass 250. Done with amp and very happy with sound. Dac was a ;lot more trouble for me. I tired many, from Schitt Yggy to Denefries terminator Plus 12 anniversary. The Schitt was good for a minute, but ultimately the Holo Spring May KTE made me smile. Source was a Mac air which was good for a minute, then down the streamer rabbit hole. Tried all the Eversolo models  from 6 to 8.The Hi Fi Rose 130. It took a aurender N200 to make me smile. I like very good mids and I researched that Dynaudio would foot the bill and it does. Wire and cord is another rrabbit hole. Research led me to cardas and that is what I tweak with. 

All you need for very good sound is a (preowned) Hegel 590 for 6k, and a great set of speakers. That’s it. Well, a decently set up room too. 

+1 unsound

politically incorrect it may be, but “WAF” is a factor, maybe even #2.  some of us have little control over the room, which affects everything. 

most of us follow an evolutionary path - trial and error. I would recommend prioritizing a keeper amp or speakers and build from there.  

the “max out the source” hypothesis was proposed by Linn to sell turntables. Imho, it’s backwards.