I think I have to be more precise:
my 2 empegs do the same:
@home:
on: LED off
standby: LED blinking
@car1-VW Polo (self install):
on: LED on
standby: LED on
@car2-Audi A3 (professional install):
on: LED off
standby: LED blinking

differences between the 2 installs:
in car1, I connected the amp remote to the ign. switch wire instead of amp remote wire (blue wire), cos this wire was always on. Is this normal?

nb: I already changed the 2 wires (ign. switch & power), due to VW home 'iso' connector.