How much amplifier power do you really need?

[RebelMan]

I did a bit of experimentation with the configurator on the D250 which is an interesting case:

For a D250 stereo, the ADH sections is:
"ADH_CONFIG":{
    "VOLTAGE_0DB":55,
    "PUISSANCE_0DB":250
  },

And for the D250 stereo, the same section becomes:
"ADH_CONFIG":{
    "VOLTAGE_0DB":55,
    "PUISSANCE_0DB":1000

55V under 6 ohms is a power of 504W, so about twice the rated 250W RMS

The way you bridge your amplifier (turning it into mono) is that instead of connecting your speaker between the black post (connecting to the ground) and the red post (swinging between -55V and +55V) is that you connect it between the two red posts and you invert one channel. So each red post still swing between -55V and +55V, but because they are in opposite phase, the difference between the two is not double, swinging between -110V and +110V between the two.
Guess what, 110V is 2016W under 6 ohms, giving once again the rated RMS power of 1000W for a pure sinusoidal tone.

@RebelMan what does continuous power means? I am reading as RMS power on a pure sinusoidal tone (or tones) that the amplifier can provide on a continuous basis. With that meaning, the peak power of such signal would still be twice the RMS power. This is intrinsic to the nature of the Sinus.
The only way for it not to be true would be to use a very different kind of signal where the crest factor would be much lower than 3dB, which is possible but quite unlikely in my mind because it would be very different from any measurement protocol of audio equipment that I know of (but I'm not pretending to know every one of them.)

I would like to think that peak power could be reached for a short time too but how short?  According to HiFi World it would have to be less than 0.5 sec.  Fortunately, they were able to mimic peak power occurrences within 0.2 sec.

Is there a typo in the second code snippet?  Shouldn't this...

And for the D250 stereo, the same section becomes:
"ADH_CONFIG":{
    "VOLTAGE_0DB":55,
    "PUISSANCE_0DB":250

read like this...

And for the D250 dual-mono, the same section becomes:
"ADH_CONFIG":{
    "VOLTAGE_0DB":55,
    "PUISSANCE_0DB":1000

While your math computes and your logic is rational I do not think it is applicable in this case because the 250 is not operating in stereo mode when power output is 1000W.

It is my understanding the Devialet Expert 1000 Pro (Dual-Mono) is a bridged mono mode amplifier.  By definition a bridged mono mode amplifier quadruples power output into a given load AND the load doubles.  When the load doubles, the current doubles.  This is why a bridged mono amplifier "sees" half of the impedance.  In other words, an 6 ohm speaker behaves like a 3 ohm speaker to the amplifier.  The math in this case would be computed as follows...

The 250 in stereo mode:  P = (V*V)/Z. P = 250watts and Z = 6ohms therefore voltage V = sqrt (P*R) = sqrt (250*6) = 38.72V. (If VOLTAGE @0DB is 55V then how is PUISSANCE @0DB is 250W interpreted?  Is it a voltage limiter?)

The 250 in bridged mode (1000 dual mono):  Voltage doubles and therefore V = 2*38.72 = 77.44V. P = (V*V)/Z = (77.44*77.44)/6 = 1000W. (1000W does not equal 2016W)

As can be seen by these calculations power quadruples from 250W @6ohms to 1000W @6ohms (as expected) and takes into account the doubling of voltage (38.72 to 77.44 vs 55 to 110 by your figures).  

That said, peak power for a sinusoid is computed as 1.414 RMS power.  Since peak power is 1.414 RMS power, peak power becomes P(peak) = 1.414 * 1000 = 1414W not 2016W.  How did you determine peak power to be twice RMS power?

Since the amplifier sees double the load or half the impedance when in bridged mono mode a 6 ohm load would behave like a 3 ohm load.  If the voltage were held constant on the supply side of the amp at 38.72V (which the "VOLTAGE_0DB":55,"PUISSANCE_0DB":1000 statements seem to imply as 55 is a constant in both code snippets) current would need to double.  To remain stable a bridged mono amplifier would need to see twice the impedance.  Hence, if the amplifier was stable down to 1 ohm in stereo mode then it will only be stable down to 2 ohms in dual-mono mode.  This could explain why HiFi News reported the power output of the Devialet O d’A (for which the 1000 is pattern after) slipped by more than half from 1500W@2ohms to 670W@1ohm. 1500W@2ohms make look impressive compared to the 420W@2ohms that the 140 can spare but it still only amounts to a 6dB gain overall.