Axiom Home Page Forums General Discussion Stereo Tube Driver Pwr

Now my confusion.
The M80's have an input impedance = 4 ohms, and an spl=95 dB/W/m.
The M60's have an input impedance = 8 ohms, and an spl=93 dB/W/m.
And both require 10W min. to be driven.
This tells me that for a given I/P power, regardless of the input impedance, the MT80's are easier to drive than the MT60's.
Where did I error?
Thanks