First... is there any way to verify your headphones are not going... maybe try a different pair to see if it still happens?
also... can you notice that the pop happens at the same time as something else, like maybe a refrigerator compressor coming on or something?
Free solutions....
Try running your system off a different outlet/circuit
Cheap solutions (or free, depends)....
Try a different power supply
Try using a UPS or other line conditioning system
Pricey solutions....
Have an electrician in to check your homes wiring.
You like how I call them all solutions when I have no fvcking clue if they will work 😀