The issue is really how important this is to with the way we perceive sound! Being able to double power as impedance is cut in half (or cut power to 1/2 as impedance is doubled) will allow flat frequency response with certain types of speaker but definitely not **all** speakers (IOW the speaker has to be designed to expect this behavior out of the amp and not all are- some are designed for amps that **won't** double power). There are also more important things to the human ear that can supersede the importance of flat frequency response. Sensing spatiality (soundstage) and the presence of odd-ordered harmonics (5th, 7th and 9th) are two examples of that.
see
http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.
see
http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.