The delay between Audio Aux indication and output from the 1810c starts out at approximately .1333 sec and increases over time to over one second. Turning off the Audio Aux and back on starts the process all over. An Audio Aux to a Focusrite Scarlett 2i2 behaves normally.
Big Sur 11.6
iMac (Retina 4K, 21.5-inch 2017)
3.6 GHz Quad-Core Intel Core i7
16 GB 2400 MHz DDR4
Radeon Pro 560 4 GB