How can I tell if the Bose head unit on an Infiniti G35 has line level outputs or differential outputs? I also don't understand what the difference is either so maybe someone can explain. I'm new to all this.

I have installed a JL Audio 500/5 amplifier which only has RCA inputs. I cut off the Bose amp input plug and attached RCA plugs which I then plugged into the amp. I did not install a LOC like the VEN4.

The amp has low and high level inputs. I don't know which setting is the correct one. I can tell you that it sounds very low and muddy on the low setting.

Finally, I get a very slight engine whine when accerlating. If possible, how can I eliminate that?