I'm sorry I know this has been talked about many a time on here, but I've done some searching and can't find out exactly what I'm looking for and would like some confirmation (this is for my sub amp)
To set gain with a DMM set it to AC voltage, put the leads on the amp's speaker terminals you're using, use a 50 Hz tone (-1, 0?), and then use the equation P=V^2/R to find the power the amp is producing, correct? the R would be the impedance the sub is wired to, correct?
I've read both that you should and should not have the sub hooked up when setting gain. Don't some amps not like not having a load though? Which one is it?
Also, to tune it to match the RCA pre-out voltage, do you just adjust the gain til the AC reading from the DMM is 4V or 2V or whatever? that seems too simple.