Sound input signal, but no output to internal speakers or headphone jack.

I'm trying to listen to a record playing on my USB turntable (audio-technica AT-LP120XUSB), through one of the USB ports on my MacBook (macOS Ventura 13.7.4). I can select the USB as the input source, and the graphic display shows a signal. But, when I select the output, I can't get anything from either the internal speakers or the headphone jack. Speakers and headphones both work for other sound sources (e.g., can play sound files from my hard disk.). Turntable instructions say its output should be set to "Line" (i.e., use internal preamp). Seems like this should have a simple solution I've overlooked, but I can't find it. (Please help!). Thanks.