Start with Vo max, Io min for a driver with the built in POTs, max is CW (righty tighty), min is CCW (lefty loosey). If using a driver with dimming leads then turn the dimming leads all the way down, which ever way down is for your dimming leads POT.
After that, you can plug the driver in and you can ramp up the current to whatever amperage you're looking for by watching the multimeter and turning the built in Io POT, or the dimming leads POT.
Once the current has been measured to your desired level, you'll want to take note of the measurement, (take precaution not to bump or move the Io POT, or dimming leads POT between these next steps), then un-plug the driver, remove the multimeter from the loop and then reconnect the wires that went into the multimeter to each other so the loop is closed again and current could possibly flow if the driver were still plugged in, but its not because you unplugged it.
Then once the multimeter is removed and the cct is mended back to a closed loop, you'll want to measure the voltage (change holes, and rotate multimeter dial) so you can determine the power (Watts = V·A), and how much resistance is in your lights and wiring, or the "load" of the cct (Ω = V/A).
You can then compare this info with the other driver. Put the other driver through the same paces but turn the current up to the same as the whiny driver you just tested, then once current is the same (make sure to not bump POT after you've dialed it in, if you bump it then your voltage reading will then be corresponding to a different amperage that we don't know), unplug driver, remove multimeter from loop, mend loop, then plug driver back in, then check the voltage, if there is a V difference between the 2 drivers when both drivers push the same A, then there will also be a power difference, or wattage difference.
This would mean 1 of your loads has less Ω then the other or requires less Vf than the other, if the loads came from the same place and are identical it would be plausible that any V difference or increase in Ω from one load over the other would be due to the only thing different, which would be the WAGOs or terminal blocks. This is why I was suggesting testing voltage earlier.
I was wondering if the whiny driver had to produce more V than it was rated for to flow the same A that the other setup could flow, and only because I was guessing that the terminal blocks had a bit more resistance in them, like maybe they were made from a non effecienct alloy that ended up being higher Ω and would then require more V from the driver to flow the same A, compared to a driver flowing current through an effecient Cu conductor with virtually 0Ω. This scare was put to rest when you found the whine dependent to the driver and not the load. I was having a hard time accepting such a huge piece of metal (terminal block conductor) could be dropping V by that much, but your current/voltage test could tell us just how much more effecient one is over the other.