Hello Madkinson. I had the same problem. What I found was that my webcam microphone array was turned on. Go to Control Panel, Hardware and Sound, Manage Audio Devices, and ensure that your LP converter device is the default device. Then check any microphones (arrays), by selecting them and clicking on Properties, Recording Level, and ensure that any devices that you are not using are muted. I would also turn the amplifier down as low as it can go. That will not affect the signal strength from the Tape Out jack, unless you have set it to variable. Normally it is fixed.
Hope this helps. Let me know how you make out. If that doesn't fix it, I might come up with another idea. Have a great day.
Regards,
-Phil