2 decks?

i have a/v headunit already and want to add alpine ipod deck..
so i am thinking using a/v headunit as when i watch movie and when i use it for backup camera..
and all the music listening will be on alpine deck..

is it possible to just t-tap wire to aftermarket harness??
and turn 1 deck off while others playing??

No it is not safe to do that.  I am sure the A/V unit has an aux input.  You can run audio out of the alpine to the input of the A/V unit.

I was going to say to eliminate the Alpine altogether (I already regret saying that, sorry fellow Alpine lovers...) and plug your I-Pod directly into the A/V units' AUX inputs.

Why can't he use one HU at a time? I mean, he could even have them both connected to the same set of speakers, as long as ONLY one unit is powered on at a time.

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

yeah actually pac makes a aux input for many of those factory units not sure what your av unit is to add an aux also i have actually done this in a van for a client once diffrent reasons but same concept have to use a relay set up to do it if you need it hit me up and ill be more than happy to send you a schematic for it.

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keep it greasy