Blu, regardless of your speakers, there's no need to think that your 805 needs an "upgrade"; this tests as a very powerful amplifier, including into 4 ohms, and should have no problem in most applications with either the M60s or the M80s(which use slightly less power). Disregard any suggestion in the manual or elsewhere to apply a lower impedance setting; all this does is to reduce the maximum power available.

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Enjoy the music, not the equipment.