I have a C400.4 and have a question about setting the "input signal" to either "Low" or "High" on the amp. The manual says that if I have a head unit that puts out a 4V or 8V signal to the amp that I should set the "input signal" selector switch to "High". My Alpine CDA-9831 puts out 4V so I did this and immediately noticed that my volume dropped to about half of what it was. Specifically, my volume ranges from 0 to 35. Normally, I listen to it on about "19". Now that I have changed my input settings on my amp to "High" I have to turn the volume up to "30" to get the same effect. It is like the amp setting has cut my volume in half.
I have not changed the gain settings on the amp nor changed anything on the head unit. I have since switched the settings back to "Low" which goes against the user's manual directions but now the volume level is up where it should be.
Does anyone have any idea what is going on? What are other owners of this amp doing with this setting?