Sure, I have thought about this. But even the best model in the Q series, the Q3, has a little hot tweeter and lacks BEITZIM in the bass. No so with this new S5 and CAT.
Prior to this, the best I heard magico was with the extremely powerful and very expensive Balabo amps. (Interesting that no one mentions these anymore, but I thought they were seriously good.) But I think a lot of things have changed in their design over time.
Good!
As for the Q3, that's the particular model I have, and the one I've played with the most. I can tell you that you can go from very fast, tuneful bass to anemic with just a change of power cords.
As you said, some amplifiers can be slow and mushy, and the Magicos will let that through. I have never heard the BAlabo amps on Magico, but I heard much cheaper amps, like the Hegel, sound incredible on my Q3s.
cheers,
alex