Dirac needs to work in the digital domain . . . that’s why it’s called DSP (digital signal processing). That kind of processing is not feasible in the analog domain. Until recently, processing typically was done at 48 kHz or 96 kHz, so 192 kHz is current state of the art.
Some DSP devices can be fed with an analog signal; however, it is converted to digital before processing and then re-converted back. So I would not advise doing DAC before Dirac, as you’d be adding a DAC-ADC cycle to the signal processing. In my experience, the fewer conversions, the better.