My father had some audio cassetes he wanted to digitalise, and he asked me to research it. I asked around on IRC and Discord, and I was told to use a tape recorder connected to the audio input of a PC. I only have two PCs with audio input, my desktop, with Haiku, Linux, Windows XP, and FreeDOS, and my headless laptop, with Windows 98, Windows 2000, and BeOS. BeOS being "The Media OS", I decided to go with that.
Then I had to procure a tape recorder, not having one at home. I eventually got one from my grandmother, but I didn't have any tapes to test it with!
Well, Sunday night, I got a tape, I connected the headphone jack of the tape recorder to the microphone port of the laptop, opened up SoundRecorder, pressed the record button, and pressed play.
An hour and a half later, I stopped the recording and tried to play it back. No good, the recording was incomprehensible. I then tried lowering the volume on the tape recorder, and it started sounding much clearer. Monday morning, I made a new recording, and it worked.
Mission accomplished.