Hi and welcome,
Lots of good advice given by others, but just to update you a little, NAD's "soft-clipping" circuit has been a feature for years of NAD amplifiers. What it does is, at the expense of slightly increased overall distortion (measurable but likely inaudible), it prevents the "hard" and nasty-sounding waveform clipping of conventional solid-state amps driven past their limits. I'd leave soft clipping turned off if I were you.
One poster suggests that the possible 4-ohm load of the Cantons combined with the 4-ohm M80s may be a bit too much for the NAD, and I'd agree.
In the past, Canton speakers had a very "Germanic" sound typical of lots of German brands---a somewhat pumped-up boomy bass, recessed midrange and greatly exaggerated upper highs--cymbals, etc. We used to call it "boom and tizz".
The Axiom M80s are more "linear", better balanced through deep bass, midrange and highs. That will make them sound quite different from your Cantons if the Cantons still have the German voicing.
And for sure try some good movie soundtracks and CDs. MP3 stuff at 128 kbps played over linear speakers like the M80s will reveal any audible defects. Use 320 kbps or higher files to preserve transparency and avoid harshness.
Regards,
Alan
