Hello groy67 and welcome.

There is no burn in period for the M80's. Nad makes some nice gear, as long as the amp is not shutting down/going into protect mode it should be just fine.

What you might be experiencing is that the M80's sound different than any other speaker you have owned before. Spend some days doing extensive listening, and see if you get accustomed to their sound.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne