I have an old broke VW am radio. I would love to use it with my smartphone to play music.
While search about converting old car radios. I found Bluetooth AMP boards on eBay. For $13 shipped I figured I'd give it a try.
Here is the amp. It's a 2 channel, 25 watts per channel, runs on 8-24 volts.
So I tested the amp out on the bench. It sounded really good thru a pair of surround sound speakers.
1968 Beetle, 1964 Panel, 1984 Vanagon Westy