There is a Lps kit brought from taobao to replace the built in switch power. It is a dc connector kit and is quite easy to change.

It's useless for replacing the external power supply of Mac mini, as there are quite a number of switching power supply modules on the mac's motherboard. (below pic. green and blue parts). Although there are switching noise on these parts, Apple did a lot of engineering works to reduce the overall emi emission including the external smps. BTW, replacing a larger power external supply will not burn the motherboard.

I use my old mac mini as roon core and would like to change to Lps. The internal switch power shows 12V 7.1 A, total power is 85W. Can I use a 12V 12A to boot it up ? I fear that it will burn the motherboard. Any ching know