I have installed a kenwood double din head unit, and have always had it just faded to the rear 30% as it's quieter in the rear than the front, if left faded 0-0 I have a connects2 canbus kit and the iso plugs for front and rear are plugged in, as well as the rear rca's. the rear iso's don't do anything, and the front rca's as well, do nothing. So all, signal comes from front iso, and rear rca's. my question is, if the rear are amplified (they are, VAG-Com confirmed) then why are they quieter? and if it's because the output's on my head unit's rca's are a lower voltage then perhaps newer models, what can I do to counter this, other than just fading 30% rear? is there an inline amp for rca's?