Fleetwood -- prior to installing a blaupunkt reno sqr46, I used one of these
https://www.crutchfield.com/S-ai3PeOuvHIS/p_13691180/JL-Audio-MBT-RX.html?XVINQ=GLX&XVVer=1J1U&awcr=699425553119&awdv=c&awnw=g&awug=9195404&awkw=pla-504079980672&awmt=&awat=pla&gad_source=1&gclid=CjwKCAiA9vS6BhA9EiwAJpnXw_GUJqeUjEYksNmdQqDy erCiHoPzSBDRV3RgkCZnqYgVo8Wu5llkFBoC1mkQAvD_BwE -- allowed me to use my iPhone as a "head unit" for my car's stereo amp (also an ads) driving the front speakers, installed it under the passenger seat and used the same power source that was already there for the power amp -- my iPhone's volume controls served as the volume control for my stereo. Worked great and the price was very right. Pair it with the Rennline iPhone mount and you'd have a solid/minimalist system