The DN9630 does not contain an ASRC (Asynchronous Sample Rate Converter) -this means that the the sample rate on the USB side (and seen by the DAW) will match the sample rate on the master AES50 side.
The front panel toggle switch allows you to specify the overall sample rate of either 48 kHz or 96 kHz.
It is important to be aware that the toggle switch is read and the sample rate is set at power on.
This is purposely designed-in to stop the sample rate being accidentally changed during recording.
If you wish to change the sample rate you need to unplug the USB before changing the sample rate switch for it to have any effect.