Hi D Rick,
Much of what Nickb and Murph say is quite accurate. I have done double-blind tests of older Klipsch speakers, including the old Heresy, compared with non-horn-loaded more neutral speakers like Axioms and some other Canadian brands during the time I was editor of Sound Canada magazine.
You'll find the M80s are exceedingly "neutral" compared to the Klipsch's. By neutral, I mean that the frequency response of the M80 doesn't overemphasize or de-emphasize any octave of the musical spectrum.
Klipsch horn-loaded speakers in general are not neutral. They are colored, especially in the critical midrange and treble regions, which are exaggerated and tiring with longer-term listening.
You will find neutral sound really pleasing and natural, even startling, especially with good recordings. Bad recordings will also be accurately reproduced so don't expect great speakers like the M80s to compensate for bad recordings.
I won't relate how the old Klipsch Heresys did in the Sound Canada tests in the 1980s because they may have improved somewhat over the years and I haven't heard newer versions.
Good listening with your new M80s!
Alan
