Input level? 2v - 400mv

can you guys tell what does the input level mean? I notice as i change from 2V to lower voltage the speakers get louder. why? what is the a good level to set?

thanks for the info

** learn something new everyday.

Well, the thing is that when i set the level at 2V...I can turn the volume higher. but when I set the level at 400mv - I can't turn as high as the 2V. Another word - I get the same loudness at different volume position.

Now by setting the input level at 400mv. It sounds better (i think). Is that mean whatever the voltage's coming out of the HU, it will reduce it down to 400mv level? I guess i'm seeking more of the technical answer.

thanks for the comments

By definition, Gain is defined to be the ration of (output voltage)/(input voltage)  or Vo/Vi. 

Now  if that ratio is 2V that implies that Vi < Vo  meaning the effect on the output of the will be less because you are attenuating the incoming signal more. 

Now if the ratio is 400mV that means Vi>Vo.  So the output signal is less attenuated. 

So, it is obvious that your sensitivity of the HU volume control will be better at the 400mV gain setting.  However, when you turn up the volume the amplifier introduces noise to your system, since you are operating at a lower signal to noise ratio than at gain settings closer to 2V.

Hope that helps.

Craig