I own a 352,the predecessor of the 402, and I beleive that when I bought mine I really think it was fully broke in after about 50 hours. McIntosh doesn't really address this anywhere that I can see, like some manufactures. But give it about 50 hours, crank it and love it. I hear from so many people that McIntosh is not as good as other brands and that may be so but I really don't think I will ever sell my Mc amps. I was going to upgrade to the 402 but since the 352 is ecentially the same I am adding the LED lighting from AudioClassics and plan to enjoys the music.
Enjoy your amp!
Enjoy your amp!