It appears to me that minimum resistance, and therefore minimum bias will occur with the pot fully CW.
BUT YOU DON"T WANT TO TAKE THAT AS GOSPEL. Leave the adjustment where it is, power up the unit, and measure the voltage across the 2 ohm sense resistor. Higher voltage = higher current. Including a DBT on the line input is usually a good idea too.
I'm glad this isnt easy in a way as I was/am struggling to understand it myself 😀
My mate actually owns this Nad, I will attempt to figure it out when we get a chance. Thanks for all the input!