Jason, welcome. Again, how have you "come to find" that? The 805 is a very powerful amplifier, including 4 ohm operation at those frequencies where the M80s measure that impedance(over the majority of their range the M80s are 8 ohm speakers). If you get the M80s you shouldn't assume that a problem would occur. If it did you could then correct it.

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Enjoy the music, not the equipment.