When i play the sound of my car radio whit my amplifier then sound is good.
and when i play the sound of mij Carpc (line out) then the sound is good but al little hard (but this you can adjust in windows )
But when i blay them the same time then the sound oh my radio is much softer (barely audible) and that of the carpc is the same.
The sound device's use the same line in port of my amplifier (have only one)
What can be the problem (maybe impedance ???)