Devialet with high efficiency speakers

[Confused]

In the demo that I attended they told me they had done some elaborate testing with Devialet and the Avantgarde speakers. They told me that the sound quality was better by trimming the maximum power down. Just by emperical research.

And of course there's the argument of not overpowering the very sensitive speakers.

I have no reason to question dealers findings with respect to them finding better sound quality, but the question I do have is why??