Efficiency theory?
Did i explain any? :S
Childish gesture?....Better refer to my last quote!
It gives an idea of your curious knowledge that you are asking same questions which was already answered by STJ174!
(Keep believing on this theory that it is a class a/b and non - efficient amp) ...!
When he said its a Class D and reviews on sonicelectronix also telling the same than what other facts you need?
Do comment when you got a reply mail from JBL International that it is Class A/b or Class D amp....!
Its My habit,My money,My time,My passion,My interest ....whether I complete my setup in one month or in 5 years,None of your business so better stay away!
And thanks for the wish!
No type of any personal attacks done by me to you...Now its up to you what you understand from it!
We are still friends! 
Peace and cheers!