If you don't use UC, then you'll need to setup MIDI Channels next to your audio tracks and program the cc level on the appropriate MIDI Channel for the corresponding Preamp. Inside the Studio 192 are internal MIDI Inputs to control the preamps using MIDI CC and Program Channel commands. See page 13 of your Studio 192 User Manual entitled: 4 Controlling Studio 192-Series Mic Preamps from your DAW.
In your DAW you'll need add a MIDI Device, and use the PreSonus Studio 192 MIDI Input as the port to send to.