Is there a such too much power for speakers?

One issue is the gain of the amp. The gain needs to match with the gain of the pre-amp and the efficiency of the speakers. If you have a high gain pre-amp and a high gain amp and high efficiency speakers, you may end up with the volume control being in the very beginning of its range, which can be a problem. If you are only using the lowest 10% of the volume control, you do not have much control.

Many traditional high power amps are class AB, which means they are class A in the low end of the range and class B at higher outputs. Many people find class A to have a better sound that class B. So, where the amps changes from class A to class B can be important. A high output amp may have more class A range, but that depends on the design of the amp.

One of the reasons for high power, is to coup with low efficiency speakers with difficult phase angles. With easy to drive speakers, the high power may be wasted. But also look at the current the amp provides. High power with no reserve does not help with difficult to drive speakers. An amp in that range should double down into 4 ohms and again to 2 ohms.

One disadvantage of high power is that it makes it much more possible to accidentally blow out your speakers.

So, yes their can be disadvantages to high power amps.

$75K for amps and $20K for speakers seems like a mismatch. I would suggest listening to some lower priced options also.

The issue with very high power amps and damaging speakers is not from sustained listening but from a sudden burst, which can happen by accident with a bad setting. For example, you can have mute on somewhere back in the chain and try to turn the power up to listen. Then you realize that mute is on so you take it off and bam - 500 watts into your speakers. It also can happen when you have a wrong input and turn up to the volume. When you change back to the correct input the same thing can happen. These type of accidents do happen and, with high powered amps, it can be a problem. It only has to happen once.

Of course constant clipping is also a problem, but with a $75K amp, it is probably not going to clip very often.

fundsgone62 - Sonus Faber Cremonas are hard speakers to drive. I agree they require a lot of power (actually a lot of current) to drive them due to their phase angle at low frequencies. I tried multiple amps on them and ended up with Mark Levinson 432 with 400 watts per channel. However, other speakers can be much easier to drive. It depends so much on the design of the speakers.

Not sure about the SE, but the Elipsas have a somewhat demanding low end. They drop to 2.5 ohms around 100 Hz and have a large phase angle around 70 Hz according to the Stereophile review. So, even though they are rated at 91 dB, they may need an amp with significant current to deal with the low end. The SE has a new crossover, so it may have quite different measurements.

I doubt you would hear much difference between 400 watts ad 650 watts, although design differences can also cause different sounds.

I would ask you dealer for some loaners. At those prices, I would definitely want to listen to the options.