The Bose speakers in my 1999 Miata were shot. I had to replace the entire sound system or buy Bose replacements. I chose to remove the head unit and install a bluetooth amplifier.
I removed the head unit and both speakers from the car.
I found an amplifier with a wired remote that fits in the ashtray slot.
I kept the original speaker wires and extended them back to the new amplifier.
While the console was off I replaced the torn shifter boots.
I made some brackets for the amplifier.
I installed the amplifier underneath the rear deck, behind the inner trunk liner.
I put a 5xRacing aluminum plate over the original stereo slot.