I installed a RNS-E Nav Plus, glovebox 6-cd changer, and sirius sat radio in my '06 S4. Everytime I switch to a different item, the volume level is different. For example, keeping everything on the same volume level, playing CDs is the loudest, then comes FM radio, and Sirius is the quietest. Everytime I switch I always have to adjust my volume because it's either too loud or too quiet. So, I was wondering, is this normal? Is this what everyone has experienced either with their own install, or with those that had an audi that came with nav plus option?