Thanks again for all your help. I don't feel confident to do the re-terminating of the tonearm cable myself. I'm fairly new to this game of cart rolling and using several tonearms. While I've managed to become quite handy in cartridge installation and alignment, I've never touched a soldering iron, believe it or not. So I will need to find someone in my part of the world to help me with this. And perhaps even better, teach me how to do it myself the next time.
BTW: the XLR to RCA adapter is not inside the Phono amp, but an external short piece of wire with female RCA's on the tonearm cable side and male XLR's on the amp input side. So re-terminating the Reed tonearm cable would take this out of the equation completely, which might prove to be sonically beneficial. But of course getting rid of the hum is my main priority.