Good point. With the higher supply voltage, there would theoretically be more clean headroom before clipping, but to be safe, it'd probably be best to set it at idle battery voltage to ensure the system would never clip regardless of whether the car was running or not.

Is there way on a head unit rca’s that only put out 2 volts on the preamps to put say a DSP or EQ to up those volts? Or would it be kinda dirty since originally you’re starting with just 2 volts? Have an Alpine INE-W940 I want to put in my wife’s car but I thought it had 5 volt preamp RCA’s but I see it only has 2 volt ones. She plays things loud so don’t want distortion coming out of her Poweramper amp so hoping that HU will be ok or can up those volts without making them dirty.

The music you’re going to listen to isn’t 0db so it you set your gains with 0db you’re technically losing some power. By setting the gains with a -5 db or -10 db test tone you’re accommodating for the music you’re listening too

@@magictoaster806 Thanks a ton for your reply! I am just trying to figure this all out. I have never set amp gains properly with a scope and now that i have one I want to do it properly. Except for my brand new Pioneer AVH-2550NEX head unit, I am working old school and have a Linear Power 2002 on 2x 10" vintage The Crunch subs in a ported box I custom made tuned to 36Hz then I have a vintage Rockford Fosgate 400.4 on my front and rear 6.5" JBL component mids and tweets. I am not into the SPL thing I am striving for SQ but still want the ability to bump a little. I was setting my subs with my HU cross set at 50Hz and my frequency generator at 50Hz. I am using the same freq generator that you are btw. So should I strive to set my gain on the generator to -5 or -10 for my subs and differently for my mids and tweets on the Rockford Fosgate?

You need to put the radio settings as you listen to the music. Like he put the sub output on the radio all the way up before setting the amp. That way you get clean signal all the way through. Cause if you adjust it flat, when you want bass, you are going to bring distortion.

When setting amp gains, should the car be at operating temperature and idling? Or just running off of the battery? I'd think you'd want it and operating temperature idling since that's around where the car will normally be running at when you are driving around.