I've done it plenty of times before using after market stereos with Pre-outs but I want to keep my stereo standard this time. I was looking to see if there was a Pre-out of something similar used for the Interscope that I could use. Doesn't look like there is
I'm stuffed if I know how to get an ignition only source for the amp or how I would connect it
Meanwhile on the other side of the world, I'm in exactly the same boat myself - I bought an amplifier today, what timing.
The row of Mini-ISO connectors - on top, the yellow, green, and blue plugs - ought to have a line-out somewhere in there. It's usually the yellow in other standard-compliant stereos (blue being used for the CD changer/line in, and green being the steering wheel controls) BUT rumour has it that FIAT have not obeyed the usual standards.
On a 500 with Blue&Me like mine you would expect the line in and remote control capabilities to already be used - I was hoping perhaps to find an unused yellow plug and then to try wiring a pair of RCAs to it, hope for the best... but it is risky because somewhere in there is the CAN bus, and you wouldn't want to stuff that up for fear of affecting other CAN devices.
So I'm going to keep looking and see if we can uncover the full pin-out.
As for your switched live, the large ISO power connector on the bottom *should* have a power antenna/antenna amplifier wire, but again, it comes down to whether FIAT followed the standard when they ordered this unit from Blaupunkt or whoever is the OEM.
If all else fails, you can use the cigarette lighter as a remote-amp-turn-on source. Quite safe to do that, just means the amp will be on whenever the ignition is on - and more annoyingly, it won't be on when the stereo is on and the ignition is off.
Something goes 'click' when the stereo is turned on with ignition off, so there must be a relay arranged to provide power when the stereo is on - we need that pin diagram to find out which pin it will be on.
Today I've bought a Sony amp for my front speakers and will perhaps end up using speaker-level inputs (like you, I've been doing 'installs' for years, and I've never used speaker-level inputs) - FIAT/Alfa do it with the Interscope and Bose upgrade systems for various models, so it can't be too bad. You do have the advantage that high-level inputs are less susceptible to interference and you only need speaker wires for the hookups. Also, the Sony amp will turn itself on when it detects a speaker-level input; no need for the remote turn-on wire you're looking for. (I need that for my under-seat subwoofer, though
)
-Alex