What does NOM mean on the gain knob of Alpine V12?

[n2audio 5,000+ posts]

x20 pretty much hit the nail on the head, but this is the most applicapble definition I could find:

From google "define:" -- The optimal level of operation for a system. Nominal Range The normal range at which a system can operate reliably, under normal conditions.

Its just that I had a single JL audio 10W3 at two ohms and it sounded good at just 1/4 gain (halway between all the way down, and NOM)
I thought it was a drastic difference to go halfway up with 2 10's, or iis that to be expected?

As the chart suggests - changing the impedance can change the voltage needed (gain setting) to get the desired power