My brother has 500 SF living room, 15ft ceiling. He has five NHT SuperZero + one SW2P sub and power by a HK 50WPC 5.1 AVR. Loud volume like I am used to. Never clips. Never goes into protection mode. 50 watts per channel.
Perhaps if I could see an AVR actually go into protection mode, I may change my tune.
Now I see the problem, what you think is loud is different than what I think is loud...
Since 1 nht running with 50watts going to it and a listening position 15 feet away {easy in a 500sq ft living room} , will only give you 87db {with 3 db headroom}, thats if he had it turned all the way up with all the trims all the way up and the avr was actually pushing a real 50w... I watch Ellen at 90db, lol, never mind music in the big room....
The other issue is I don't know if you ever ran an avr at full tilt, but they sound terrible, I don't care what anyone says, get a 20w amp and run it full volume through a speaker and it sounds like sh!t, then get a 100watt amp and run it to that same db level and it will sound fine... I don't know why, and I don't really care why, its just a fact... You want proof get a lepai 2020 and run it full blast through a pair of polk bookshelfs you get around 85db on the spl meter and it doesn't sound great, next plug it into an r700 and play it at 85db, sounds great....
Headroom makes a difference, in component life, sound quality, and sound level, if not why don't a;; avr's just come through with 50watts....
And Im not sure if I read the posts rite, but if anyone thinks more watts don't make a difference, they are nuts, then why don't we all have 50x5 avr's? I know why, because they are not loud enough...

its simple rocket surgery, more watts means a bigger smile a bigger smile means more happy guy holding the remote...
here is the math if you are interested..
(2X50w=
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)<(2X100w=
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)<(2X200w=
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)<(2x400w=
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)<(2X1000w=
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) see its, easy when you draw it out as a math problem...
heres the math for acu's brothers room 500 square ' X 87db X 5 square route of 50w =