That's exactly what McIntosh amps are designed to do with the autoformer regardless of the load characteristics. That's why you aren't going to get the best sound from Focal using their amps. Let me try to explain it...
With a typical direct coupled voltage source amp the goal of the amp is to just drive the voltage into the load regardless of impedance. If the impedance is high, it just pushes the voltage with less current. If it's low, more current. That's not what McIntosh amps do.
McIntosh autoformers are designed to maintain constant power regardless of load. When it sees a high impedance, it doesn't just maintain the voltage and let the current float. It will drive try to drive the same level of energy, both voltage and current, into that higher impedance load. The same for low impedance loads.
The problem is that Focal designs their speakers to be powered by a voltage source that lets the current float around a bit. Focal uses low impedance through the bass region to get the better bass response by letting the amp drive more current into the speaker. Beryllium tewwters cover a wide range and as a result swing from 8 ohm up to 20 with phase angles that swing downward. You see that bump in their response at about 10KHz because that's where the phase angle is about 0 degrees and the impedance is pretty benign. You're getting good energy transfer, plus that where 1 inch tweeters begin to become very directional. If you're driving it with an amp that only seeks to achieve flat output power, you're going to get overwrought highs as the impedance rises sharply past 10KHz and the phase angle goes more negative. The speakers is expecting to get less power in the form of less current. That's what it's trying to tell an amp that's acting like a voltage source. But that's not what autoformers do.