Simply, the switch just limits out put power so as to not overload the amp and you don't want to limit the power available. The only problems might come when trying to play at loud levels. Some have gotten to that point with their receivers, Yamaha or Onkyo, and others have not. If you do find it a problem you will then have an excuse to buy some monoblocks to power the M80s
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BTW, I am envious that you have the room for 3 M80s across the front. I ran my M80s with an M60 as a center briefly and it was the best soundstage I have heard. And Welcome to the club!
