Hi JNieves,
If your Sony has actual per channel continuous power output ratings in the specs for 4-ohm loads (ignore the "dynamic power output" which is a bogus spec for marketing purposes) then it should be fine to drive the M80s.
If there is an impedance switch on the Sony's rear panel, set it to the 8-ohm setting for the M80s so the receiver doesn't limit output power. Don't set it to a 6-ohm or 4-ohm setting. I agree that since it's a flagship model, it should have a more robust power supply capable of driving 4-ohm loads.
REgards,
Alan
