Power supply to Pi3B+ and IQAudio Digiamp+

Hi all.
At present I am feeding A Pi3B+ via gpio 5volt pin(s) from a IQAudio Digiamp+ which has a 19volt supply.
I would like to have a separate 5volt supply feeding the Pi independently so that I can use a safe shut down method in the event of power outage.
This means that the Digiamp must no longer supply the Pi with 5volts as it does at present.
I think I may be safe to cut out the pin or pins that are feeding the 5volts to the Pi.
Any ideas on this?