What I don't understand in the equation given is how the efficiency rating is gotten. I know it's a number published by Axiom, but how did they come up with this number. is it from an average of power required to generate pink noise, or is there a real life side to this?

I ask as I am sure that the power levels needed to get the amount of sound level you desire is also influenced by what you are listening to. The amount of power to drive a tweeter is a small fraction of the amount of power needed to drive the 6.5" long throw woofer.

I would expect that you might be pulling far more power listening to a bass heavy rave club track at 90db over listening to a flute concerto in D major. All things being equal need not apply hear.

Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5