No sound using mike line in

Hi I just updated to Audacity 3.1.3. My OS is Catalina 10.15.2. I’m using Soundflower to route signals. In the past with older versions of Audacity, Soundflower and OS I was able to run a cassette player into the microphone jack and record without any issues. With my current set up I see no signal when I try to use the monitor. I have given Audacity permission to use the microphone (in System Preferences). I can get a signal if I use a sound source from Safari (e.g. YouTube). I have checked that the output from my cassette player is working (stereo cable to 1/8 in stereo jack is fine). Any suggestions? Thanks

Yes, several years ago, in order to save money, most PC manufacturers removed the stereo line-in port. So you will need additional hardware. A good, inexpensive interface is the Behringer UCA222. You may also need an adapter cable. While several less expensive USB audio adapters are available, none of the ones I have seen have a stereo line-in interface.