Power to Stereo with ignition key in position 1 (Aux position)

[Dr Pepper]

I have just bought a 2003 Cayenne S (RHD) which has an aftermarket stereo fitted – an Alpine IVA-W205R.

The stereo is currently wired so it only plays with the ignition turned on / engine running.

I want to rewire so it also I can listen to it when the key is just inserted but not turned – position 1 I think – or what I call in the ‘Aux‘ position.

I have trawled through both the LH & RH dash-end fuse boxes with a meter but I cannot find any feed that goes live in the Aux position - but there must be a feed somewhere as in the Aux position, I hear / see power going to the steering lock & dash clock.

I could wire in a manual switch to provide power to the stereo when the ignition is turned off but there’s no failsafe measure to ensure it’s not left on, say overnight – unlike when removing the key before locking.

I’ve thought about fitting a 12V timer relay which would give me say an hour of power to the stereo & then auto switch off - like many Fords have – but taking power from the Aux key position is the route I would prefer to take.

Can anyone help me with this please?