Loss of Audacity external sound, though program still records

I am turning LP’s into MP3’s using an AT USB turntable. All was working fine with Audacity, when suddenly the exterior sound from my IMac failed, so I cannot monitor what is being recorded. The program is still recording, however. Also, Interior source playback with my Mac work fine.(Music, internet sources, etc. )

Make sure that Transport (menu) > Transport Options > Software Playthrough (on/off) is checked.

– Bill

Also, Transport > Rescan Audio Devices followed by checking your Playback Device under Audio Setup.