Welcome, Zuruck!
You'll find that here, like everywhere else, there are those who think that different amps sound different, and some who feel they all sound the same (excepting tubes).
I personally wouldn't recommend vintage speakers. There was no technology available 20 years ago that isn't available to speaker designers today. And you're likely to have maintenance issues with cone surrounds needing replacing, etc.
I don't remember anyone running M80s with McIntosh in particular, but there's absolutely no reason to think that it would be a bad match.
By far, the biggest variables in the sound will be the speakers and the room. So really, there's no better way, in my opinion, to buy speakers than to try them in your own room for 30-days risk free!
