Both are. No amplifier has one single power number, ever. The power rating for example differs between max and peak at 1% THD. Different measurement, different results. The one at the knee is the power at near limit of the amplifier. Different measurement, different result.So which is max power. the 1% thd bar graph, or the 0.001% power sweep.
The knee power is the conservative one and is less precise. The 1% are aggressive one and precise. Both pieces of information are provided and consistency is observed across all reviews. I don't put the cursor at max of the sweep to please one company at the expense of another showing it at the knee.