How many amps (electrical) ?

If that is true - that is exactly what I need to know.  I could (in theory) have up to 6 Sonos Amps on a 15 amp electrical circuit.  I am building a new Loft and currently do not own any Sonos equipment, so I can’t do any measurements, but in my system planning, I was thinking I would need 4 Sonos Amps to do what I want to do and they would all be co-located, so most likely on the same circuit.  I wasn't sure if I could do 4 on 1 circuit - but if the 2.5A holds true, then 4 SA shouldn’t be any issue.

I doubt that all four AMP’s will be simultaneously operating at their full output on a sustained basic. If this is the case, provide earplugs for everyone.

A big part of the data plate draw rating is usually the startup surge, if you switch them individually your total initial draw will be much lower. It will also likely be less stressful for the Amp’s internals if all aren’t trying to draw the startup current at the same instant.

I have used individually switched power strips to reduce startup surge, flipping the switches a second apart is plenty to reduce the surge current. A couple smart-switches would be less hassle today.

A Sonos Amps is ‘always on’ or in some sort of ‘standby’ mode, correct?  I do realize that there is a power switch, but generally, it would be left on so you can open the App and just start playing, correct?  I would assume it would go to sleep or to a standby mode if you stopped streaming for the night or whatever, right?  The power switch would see virtually zero use.

Yes a Sonos Amp is always on when plugged in.

There is no power switch.

Yes, you leave it on so you can just start playing.

Yes it goes to sleep mode when unused. Not zero power though,7.3 Watts.

So yes, in normal use a power switch would see little use.

In some situations it is nice to be able to power down a Sonos easily:

-- It can be needed to cure some system issues. 

-- If you are going to be away for a time or you are expecting power disruptions.

-- If you have multiple devices on the same circuit and want to reduce the initial surge load when all are powered up together. For one example utility power drops for a time.

The first two apply here and as unplugging the Sonos is a major effort involving having an assistant to help move the TV stand or using a ladder to reach some Sonos, having an easily accessible switch is a big plus.

A remotely operated power switch might be useful. If you go this route, I suggest that you switch power only once a day, max. Power ON is a very stressful event for electronics. You’ll never be able to drag the number out of a manufacturer, but after a fixed number of power cycles (at a given room temperature) the unit will fail. Power-up and leaving the unit running for weeks or months is only one half of a cycle.

Aside from troubleshooting where sometimes multiple power cycles are needed I’d not even switch them once a day. When troubleshooting I try to give them 10 minutes between unplugging and re-plugging for just that reason.

Sonos I switch off to save power are off for a week or more, the dining room set are only on Thanksgiving to Christmas when we have family over to use that room. Our media room Arc, Sub and Surrounds are turned off for at least a week before being turned back on, and often left off for a couple months or more. Everything else stays on unless power disruptions are expected.

In the OP’s situation I’d leave everything powered all the time, but set the switch to not auto-power up after a power failure, allowing them to turn on the units individually a few seconds apart to spread the initial surge. Maybe power down for a week or longer vacation if you also unplug a lot of other appliances.