Ok I just saw pictures of the connection between the APW9 and S19 .
Difficult but possible to replace this connection with short power cables .
The power connections are not the problem. How the PSU's work is the problem: Modern miners do not use a fixed, universally available 12VDC input like older miners did.
In older miners 12VDC was fed to each hash board and each board had a second regulator on them that lowered the 12V to a level suitable to feed the strings of chips. Those secondary regulators introduced an efficiency loss plus the low voltage limited the number of chips that can be in a string. Modern miners directly control the PSU to set voltage to the strings and that voltage will be variable to somewhere between 15 and 21VDC depending on the model of miner and the miner settings. So, now not only are there more chips in each string but the voltage fed to them is now directly adjustable by the miner controller talking to a custom PSU and because there are no secondary regulators that increases efficiency by several %.
to be clear the controller looks at the oem psu and reads its name model number.
so if your replacement psu has a different model number the controller says fuck you I want model 1 and you gave me model 1a
I had this happen with whatsminer gear. the psu died they shipped me an upgraded psu
P11 vs p10 and the controller needed new firmware to read the new psu.