Techy stuff about amps

[RUSSET]

Some you may already know this stuff, but for those who don't & are interested in the tech side :
http://www.gmarts.org/index.php?go=216

[Graylion]

Not quite sure if they have it right. To double the volume you need 10 x the power so for doubling the volume of an AC15, for example, The Shads would have needed 150 watt amps! (All other things being equal of course - speakers and their efficiency etc.) I have often wondered if they thought that by "doubling" an AC 15 to an AC 30 they thought the amps would be twice as loud?
Going the other way, of course, it means that a Marshall (or any other) 100 watt monster is only twice as loud as a 10 watt amp!