Car audio help?

[84chevyguyid]

Hi all, starting to install my audio equipment in my 86 crew cab. 8 years ago I purchased a JL Audio JX400/4D amp, a JL Audio JX500/1D subwoofer amp, a CP110LG-TW1 sub, a pair of JL Audio TR650-CSi 6-1/2" speakers and a pair of JL Audio TR400-CSi 4" speakers. I dont want to bother with a head unit and was planning on plugging my iphone into the amp(s) somehow. I havent paid attention to car audio stuff for a long time but it seems like there used to be a bluetooth device the the phone could hook to and feed the signal directly to the amp(s). Years ago in my old corvette I built a custom dash and the mounting spot for the radio went away so I got a headphone to rca adapter cable and plugged it my headphone jack on the phone and directly into my amp, readjusted the input gain controls and it worked great. Was hoping to do the same thing with the crew cab. Not sure how to hook to both amps to make it work the best. Anyone have any suggestions?