Basic mismatch. The generic Mic-In of a laptop is very sensitive and good for a low level mono computer microphone like a Skype headset. You’re providing a Stereo, high level signal from the amplifier, so no. That generally doesn’t work. You are listening to just shy of a thousand times overload inside the laptop.
If your computer has a Stereo Line-In, use that. Most laptops don’t, but large deskside PCs and Macs do. Some laptops can switch one connection between high and low level. You can’t just turn it down. You find that even with the controls almost all the way down, the sound is still terrible – or completely off.
You can also use one of the many USB adapters we reviewed.
https://forum.audacityteam.org/t/sound-card-reviews/8375/1
Koz