To also chime in on your original question, I would classify the Magico A3 speakers as a moderately difficult load to drive. The specs on the Ref600M (600W into 4 ohms, 27A peak, 2 ohm minimum) indicate it should be capable of driving the A3 just fine. I have not heard the pair myself though.
We currently have the Magico A3's paired with a Bryston 4B3.
We currently have the Magico A3's paired with a Bryston 4B3.