Quad Speaker System
The station has four Adam A3X studio monitor speakers. The volume levels have been set for you, so you shouldn't have to adjust them.
UA-101 Audio Interface
Here's a review that explains things pretty well about the interface .
Go to the Cakewalk Driver Download site for the UA-101, agree to the licensing terms, and choose your Operating System's install version. Download and install the driver (except for Linux which doesn't require a special driver for this interface).
Changing Sampling Rate
Changing the sampling rate requires restarting the interface. Turn the SAMPLE RATE knob to the desired new sampling rate (normally 48 or 44.1kHz). Nothing actually happens until you restart the interface by turning the OUTPUT/POWER knob turned all the way down (counter-clockwise) until it clicks (the power light goes off). Turn it back to restart. The knob then becomes the volume or OUTPUT knob which controls the headphone volume but not the volume on the quad speaker setup. It's best to make sure you've got it set to the sampling rate set to what you think you will be working with, before you start your audio software. Just makes things cleaner. If you have to change the sampling rate while you are working with applications, first make sure you've saved your session files, because doing so may have unpredictable results.