I have a 250 Expert Pro, so half your system, on a P3.
Devialet’s wording is all ab out maximum capability and is reflected in its extreme transient capability. It is not a level of power that could be sustained by domestic speakers, probably even your M3s.
There is an explanation on Devialetchat:
The above text refers to the power supplies maximum capability. So with the amplifier running at its’ absolute maximum, the power supply will need no more than 1200w continuously, which is about 5 amps in the UK or Europe, and even with 110v in the USA is less than 11 amps. To be clear, these are maximums, with most domestic listening the figures will be considerably lower, probably nearer the 1 amp or so level. Consider that most speakers will only cope with 100w to 400w continuously. If you did manage to run 1200w into your speakers on a continuous basis then melted voice coils are more likely to be your problem that the amplifier demanding too much current.
4 kw is a LOT of power, it is the kind of power that something like an electric oven, a patio heater, or large room heater would use. Devialet’s get hot, but not hot enough to heat your living room in winter or roast a whole chicken.
On top of that, I’ve spoken to Devialet and they do not recommend power regeneration or conditioning, but it doesn’t stop people like you and me using it.
I’m in touch with their Chief Engineer, I’ve half a mind to ask for a definitive option from the person who designed the power supply and amplification.
I use the P3 because of the potential benefit of lower impedance. Again, whether that makes any difference I’ve not come to any conclusions.
So I really can’t believe that the 1,250w or 1,500w think will make a difference as we are not talking continuous demand and the maximum power is almost certainly not continuous and when it is needed is is coming from internal reserves.