DAC to unity-gain buffer
Credits to @SvenB for being the first that pointed to the right direction. 

Even on steady sinusoidal AC source the current through power supply components does not go higher than hundreds of milliampere when connecting the AC power the current might go up to 2 amps.

The worst case scenario is when the AC power was disconnected with C1 voltage at a maximum (+220V) and later connected while AC power was at a maximum opposite voltage (-225V).

This will put almost 450V on R1 , a peak current of 3A for a very short time (0.3ms). 

That's why components in the path R1, R6, C1, C2 D1 and D2 must tolerate a peak 3 amps current 

Tough, the continuous current might be as low as few hundreds mA.

From the comments it shows that C1 was dead first but any other could fail, usually the diodes and unpolarized capacitors get shorted, and the resistors are interrupted or their resistance grows. This time C1 capacity was altered to a lower value.  

Don't forget to add a discharge resistor ( ~100k ) in parallel with the AC input to protect the operator from the remaining C1 voltage