3 Ohm Speakers

Shouldn't be a problem.

(1) The receiver's 6-16 ohm rating is for pure sustained sine waves on a test bench driving a resistive load. Real music places far fewer demands on the power supply, heat sink, output transistors, etc.

(2) Speakers don't have the same impedance at all frequencies and they generally have higher than specified impedance over much of the audio band.

(3) In typical use, you don't run the receiver right at full full power. Even a few dB less than full power cuts the receiver a big break.

(4) Music is impulsive and varying and generally needs only a fraction of the amp's maximum power most of the time, even if hypercompressed or clipped.