When a volume control is at the max the potentiometer is short cicuited. It is the smartphone volume wich control the system. It is the same as you want to instal a preamp on an integrated amp.
You have to put the volume of the amp at the max and it is the preamp controlling the volume. But you dont touch the volume knob in the car after .
,The handbook gives no mention of this (unless I've missed something). You cannot even play the thing unless the engine is running. Reading thierry's post, volume can only be adjusted with the phone if you inadvertently turn the car volume the wrong way (which is easy to do as turning anti clockwise increases rather than reduces the volume). Upgrade was included in the spec of the car I bought 2nd hand. Happy if someone can explain where I have gone wrong but personally if I was buying new the £3500 would be spent elsewhere.
