Ok, I just got some A pillars with alpine tweeters . I have the stock 2013 audio system, I have replaced door speakers already some time ago, installed a 8" bazooka sub using IA adaptor. I still wanted some more highs closer to my ears.

Should I attach the crossover for the alpine tweeters to the unused RCA terminals of IA adaptor or just T off the front speaker or rear speaker lines ?

I assume the crossover will match impedance so the head unit will not notice or should I use the RCA jacks in the harness like I did for the SUB ?

I know this won't be perfect but just want to enhance the highs.

 

The unused RCA adapters on the IA plug have a passive LOC, tap into the front speaker lines.