Input-power listing vs Output-power rating
Just out of curiosity, I've noticed the power-input label on the XLS-1002 reads 175-watts while it's rated output is 700-watts into 4-ohms (both sides driven).
Now, given that efficiency even in class D rarely exceeds 90%, how do we get more out than what goes in?
The same is true for the XLi-800, the XLS-1002's class AB predecessor. It reads 430-watts input, but is rated for 600-watts output into 4-ohms (both sides driven).
Is this a function of a Harman-proprietary rating method? Is it not RMS?
Don't take this wrong, it's an honest question and I have both amps (just bought another one last month), but I'd like to know why there's an apparent discrepancy between the input power listing and the output power rating.