Background noise while recording cassette

This is not insurmountable. You may have asked for the wrong thing.

This is a Behringer UCA-202 connected to my analog mixer. I have two (the adapter, not the mixer).

Highly recommended.

It’s also certified for zero latency overdubbing should you get an insane urge to overdub your voice into a one-person trio. That’s why the headphones/earbuds are there. We can do this.

There other adapters.

https://forum.audacityteam.org/t/sound-card-reviews/8375/1

Koz