macOS Big Sur 11.4
My USB PnP Audio Device (a new (7/2021) Marley USB turntable) is sending signals to the Mac, I see that in the USB PnP Audio Device entry in System Preferences-> Sound. Using the Utilities->Audio MIDI Setup I see Source: Default Format: 48,000 Hz - 2 ch 16-bit Integer (close to what the Audacity Manual shows, but 48,000 rather that 44,100) - it is not alterable. When I hit record or “Click to Start Monitoring” I get nothing, i.e. no waveforms.
The Audacity app has the following input designations: USB PnP Audio Device … 2 (Stereo) Recording Channels