Ok, I just made some vids about setting gains w/ multimeter based on an amps rated output and the DCR (load) the amp will see.
I used 2ohm on a PG radial 600.1. Set then gains at 60hz to ~34.5v (just under the 'rated' 34.64v). I then addded a load to the amp, 2 RSd12's, and showed that even though the amp will most likely not clip at ~60hz but will at lower freq, such as 40hz.