High Current Amp Benefits?

[PENG]

Speakers are usually less than 60 deg phase, either inductive or capacitive. How would that spec out? At least, David Rich uses that as the max phase when testing amps specs beyond resistance, how well it holds the rail voltage at those phases beyond resistive only.

P.F.= cosine of the phase angle between V and I.
Cosine 60 = 0.5
Cosine 45 = 0.707
Cosine 30 = 0.866
Cosine 0 = 1

Thanks to Dan, he just provided the typical range for linear amps.
At the output side of the amp, the p.f. would obviously depend also on the complex load characteristics of the loudspeaker.