I doubt they can handle the power the M80s can. That and they do take more to power to reach a certain db level as their sensitivity rating is much lower, 89db compared to 95db for the M80s.
Who ever made that statement must be ignorant to the M80s specs.
When you look at the frequency response of the Swans they do not have a +/- to the 35Hz-20kHz they publish. How would one know the true frequency response.
The M80 on the other hand do: Freq Resp +/-3dB (Hz):
34 - 22kHz
Axiom gives an honest frequency response.
