Originally Posted by WinWiz View Post
But someone here on DIY told me that to maximize S/N I should adjust my gains so that my headunit is almost at max (about 60) when I play really loud. But you say your system plays loud with the volume at only 15? The Voltage on your rcas must be really low.

Selling ice cream is bad for the ears because you have to constantly ring a very noisy bell!
maximizing S/N ratios, is really only important if you're getting equipment noise, or hiss from the install.

if you've got quiet equipment, you can have your amp maxed out at 250mV, which on a 5V deck, might be 30% of the way to the stops, and not hear noise.

that's the key, is if you encounter noise, you have enough available voltage to set the floor above it. You may never need more than 250mV of voltage, if your amp can max out at that level.

In the old days, 250mV was an actual max level on some equipment, Alpine wasn't much higher at 500mV. That means that their tape decks used to put out 500mV on their pre-amp outputs, that's it! Amps used to adjust from 100mV upwards to 1V, that was a common range on the gain controls.

and they didn't all have noise!

So when you feel like you need to drive your S/N into the ground by pushing 5V of line-level into the amps, it's possibly not necessary. But if you have it, some say go ahead and use it.

Myself, I choose convenience before noise floor concerns, but if I had hiss, I'd probably think differently about it.