Absence of negative is not proof of positive

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I would recommend that you
not do it. While it may work for very low volumes, the moment you turn it up, the amp section will run out of power/ headroom and shut down.
The M80's will be best paired with a dedicated amp (if your other speakers are easy to drive only a 2 channel one will be sufficient). There are several options out there, but, Emotiva's UPA-2 and Behringer EP2500 are excellent value for money.