USB 2.0 full speed audio class max sampling frequency?
USB2.0 full speed is the same as USB1.1 full speed.

USB1.1 frames have a length of 1ms, and isochronous transfers may put up to 1023 bytes into a frame. This gives you roughly 170 stereo 24bit samples per frame – a 170ksample/s rate.

Even the simplest compression techniques as transferring the difference to the previous value instead of the actual value or joint-stereo, followed by special encoding for small difference values may nearly double that rate.