Yes, the Amp is designed to handle 250 watts of power to a pair of 4 Ohm speakers.

https://support.sonos.com/s/article/4717?language=en_US

Yes, the Amp is designed to handle 250 watts of power to a pair of 4 Ohm speakers.

https://support.sonos.com/s/article/4717?language=en_US

So the Amp is hypothetically able to handle two floorstanders that require 200W of power (and rated 4ohms)?

Does this mean that if my speakers are 20-100w speakers, the Amp actually has a very easy time driving them because they're 4ohms? I was always sure 8 ohms is easier amplification. 

Power ratings for speakers are very slippery because there is no widely agreed upon standard for assigning a maximum power rating to a speaker. In many cases I suspect that the marketing department has more sway in the maximum power rating than the engineering department. A speaker with a higher power rating must be better, right? High end speakers tend to specify more conservative numbers.

In some respects this is similar to automobiles and the maximum speed shown on the speedometer. A high number means a good car, right? Unfortunately, this does not consider road conditions. Even the road’s posted speed limit is misleading because of varying weather conditions and driver capability. 

It turns out that little amplifiers damage more speakers than big amplifiers. Low power amplifiers driven beyond their design limit tend to damage speakers. SONOS amplifiers are among the safest available. If you give me a job, “please burn out this speaker”, I’ll pick a little amplifier in the 50 Watt range. My last choice would be a SONOS amplifier. 

4-Ohms is the lowest “Nominal Impedance” that AMP should work with. Speaker impedance varies by frequency. The EVO 4.1’s are marketed as an 8-Ohm speaker, but they are kind enough to point out that there is a region, probably in the deep bass, where they dip to 3.5 Ohms. Some amplifiers will freak out at these 3.5-Ohm frequencies, AMP will handle these with grace. The earlier CONNECT:AMP would freak out.