So I decided to throw out the old boom box and install my old car stereo in the garage.

That weird hole in the head unit holds these things called "cassettes" It's what your grandparents listened to in their car or while they were jazzercising after a long day writing with pencils and pens.

I picked up a cheap 12vdc power supply to power it, and used the existing Kenwood head unit, 10 disk changer (which is what you parents listened to at their cool college parties), speakers, and an old Sony 30x2 amp I had collecting dust.

It didn't turn out too bad for a bunch of shit I had laying around.