Power of summation of two signals Let $|A|$ denote the power of the analog signal $A$. Is that true to assume $|A+B|=|A|+|B|$, for two arbitrary signals $|A|$ and $|B|$? That is the power of the summation of two signals is -at least roughly- equal to the summation of the powers of the two signals. What if $A$ and $B$ are random signals?
For the amplitude, the inequation $|a+b|≤|a|+|b|$ is satisfied. 

However, since the power includes a square calculation on the amplitude, you can find all the three ($=$,$\leq$,and $\geq$) relations. 

The difference is that amplitude is a vector, while power is a scalar.