Not sure I follow you. What do you mean by digital gain? Digital sound level is set on the recording. If you mean that your DAC has a gain on it, that it the gain on the analog side of your DAC and is often used without a preamp. As for which one to turn up, I'd experiment. Set my DAC volume at low, med and high for a day each. You may find it is a way to control harshness.
Digital gain vs analog gain
Is there a rule of thumb that guides the balance between digital input level, analog pre-amp input level and analog amp attenuation for reach your desired listening volume?