Is there a such too much power for speakers?

  More power isn’t better. Better quality design and build is better. My Kyocera MOSFET from the 1980’s is rated at 50 watts/channel, with 125 watts/channel on demand. It will push my speakers well beyond the pain threshold with no distortion. Sorry, but I think most of the stuff they make today is overrated junk. Invest in some good vintage gear.

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.

The rating of Watts can sometimes be misleading. A Krell monoblock may be rated at 100 watts -a cheap amplifier might also be rated at 100 watts. The distance between them may be huge in sound levels. Try to arrange listening sessions with loaned equipment in your own home. If you are spending a large sum of money it needs to suit your environment.

So a square wave will shorten a transducers life faster than any mega watt amp will. You just have to know your listening habits ( loudness ) and when your amp begins to clip that out going signal. Square wave formation is essentially DC. And DC IS DEATTH for a speaker. 

I was using my VAC PA 80 80 set in triode mode putting out 35 watts per side. My pre amp is the ARC LS15  They were driving my speakers that have built in powered sub woofers. I have on order a pair of Maggie's 0.7 speakers. I decided to buy a used amp that would have more power to drive the Maggie's as they like power. I found and bought ( for less that a decent set of speaker wires) a Spectron class D amp. I've spent days listening to CD's that I've owned from the eighties that I know inside out. They have never sounded so dynamic, energetic, amazing inner detail, and a wide sound stage I've never heard before. I'm just amazed on what I'm hearing that I've never heard before. So if high wattage produces what I'm hearing, give me more!!

John Ulrick produced the first commercially available Class D power amplifier in 1974.

Specifications

• Design: Class D (Switching) Stereo Power Amplifier
• Power: 600 Watts RMS x 2 into 8 Ohms, 800 Watts RMS into 4 Ohms, 1,200 Watts RMS into 2 Ohms, 1,500 Watts RMS into 8 Ohms in Bridged Mode