Thank you!! Just goes to show that one must carefully read the fine print (which I obviously didn't) ... and also not put too much faith in the examples (AI created?) one finds on the web.
I have assembled a Teensy 4.1 system which accepts audio input from a PCM1808 ADC and outputs audio through a PCM5102 DAC. When I connect them direct as
AudioConnection patchCord1(input, 0, output, 0);
AudioConnection...