Originally Posted by 808MGuy
Since the OEM HU does not have a volume level display, how do you set the volume so you can set the input gains on your amps. Do you just crank it all the way up assuming eventually it gets to max and set it that way or do you crank it all the way up and then down a few clicks before you set it?
Personally, my amps gains are always set to minimum if possible to minimize hiss. The gains of either the processor or/and a line driver if used are the ones that I adjust.
For example, for a base analog OEM system I don't use a direct to amps/processor connection, I use a line driver at the OEM HU/Nav outputs first, then to the aftermarket processors/amp and that's what I adjust for the best signal to noise ratio. That's what I did in my E46 M3 Harman Kardon OEM system, no hiss at all.
In the case of my current Premium setup, because of the issues of the bit one high level inputs being saturated with the OEM amp, I was forced to adjust only the underseat subs amp gain because I have to reduce a lot of the input level of the processor to avoid the saturation. At least the OEM mids and tweets amp gain can remain at minimum, so hiss is almost non-existent.
However, once the digital preamp device shows up then I will be able to set the bit one built in line driver to its maximum levels and set all my amps gains to minimum.