The answer is a little more complicated and it lies in understanding exactly what an audio amplifier is.
The so-called power amplifier is actually a voltage multiplier with enough current so that the voltage multiplication remains consistent while driving speakers. In other words, a voltage, not power, amplifier.
And the difference between an ideal amp and a real amplifier is in the output impedance of the amplifier. Think of this as a relatively small resistance that happens right before the amp’s speaker terminal. A lot of otherwise very beefy amps have a lower output impedance at low frequencies rather than high. Usually that’s fine. Most speakers have lower impedance in the bass and this works well.
But take an ESL, which may be 4 Ohms in the low range and 1/3 of an Ohm at the top. The combination of rising output impedance and dropping speaker impedance cause the amp to no longer give a flat frequency response. You lose treble.
Sometimes we hear this problem well in the bass. Take a speaker that drops to 3-ish Ohms in the 100 Hz range. Quite typical for 2 1/2 way speakers or speakers with multiple bass drivers. The less sturdy the amp is, the more the output voltage starts to track the speaker impedance and we are left with a loss in the lower mid bass.
So, best case is that your amp’s output will track the speaker impedance, dropping as impedance drops. Worst case is that the combination of output and speaker impedance at the top end plus the power requirements cause too much power to be dissipated in the output devices and you'll let the smoke out.