In addition, you yourself are on record saying that power was sometimes measured on the input side of the PSU. That would, obviously, give a different answer from measuring it on the output side of the PSU.
Only as reality check. All of the measurements in the spreadsheets and papers are measured between the power supply and the reactor.
Measuring power going into the power supply is a way to ensure there is no mistake. It is an extra precaution. Those AC plug-in meters cost about $50 so there is no reason not to use one. You measure the power supply overhead by turning off all power to the cell. Of course the overhead increases a little as power increases.
Multiple meters belonging to different people have been used to confirm the power measured between the power supply and the reactor. They all agree with one-another, and with the spreadsheet data. It cannot be they all agree, they are in reasonable agreement with the AC meter the power supply is plugged into, yet they are all wrong.