As others have said, either will deliver far more power than you will need. I'm familiar with those amps and they will likely have very different sounds. The Sim will be very detailed, transparent and analytical-although I enjoy the Sim sound, too dry for some tastes. The Mac will sound like a Mac, softer, less detail than the Sim.
If you are really concerned about power, you might consider the Michi S5. More power than you would ever need and built to last. I just replaced one in my system and tried the Sim North 761 when I was looking. In my system, to my ears-we all hear differently-the Michi had a better sound-the same level of detail, but a bit more natural. At about half the price.