el ohmbre

I've been studying the shop manual, reading this forum and searching the internet for days for a clear answer to this question. I have a 1986 C4 with the Delco Bose sound system. It's working reasonably well, but I'd like to replace the radio unit so I can have Bluetooth to answer my phone and add an Aux jack and USB charging port. This is just for the short term, while fixing other things that are more important. I've read that it cannot be done without replacing all the speakers because the amps are in the speakers. In other places, I've read that there is a "adapter" that will handle the change.

I bought an adapter that plugs into the wiring harness. (Of course, I didn't want the cut into the original wiring harness.) It handles the 12 main wires in the back of the radio including power, ground, speakers and power antenna. There are an additional four wires on the back on the original radio. One is "always hot" for the clock. I think one connects to the lights to dim the display when the lights are on. I don't know what the other two do. The adapter came with one additional wire for the always hot.

Is it actually possible to add an aftermarket radio and keep the Bose speakers? If so, what is the proper adapter or wiring diagram to make this work.