It always surprises me when people don't check the manufacturer's documentation that is available online at no cost. The manual for MA5200 clearly states in three places that the MA5200 is designed for speakers with an impedance rating of 8 ohms. The German magazine found exactly what would be expected for output into a 4 ohm load, but because Mc doesn't explicitly state output values into 4 or 2 ohms as they do for other products, the amp section likely becomes unstable those average loads. In short, it will work but will get hot and eventually distort the signal. Mc makes a terrific product line, but this is their entry-level integrated. Depending on the rest of your system, a different model might be a better choice. An excellent source for advice would be Audio Classics in Vestal NY. Highly recommended.
Good luck and happy listening!