For best decoded audio quality ensure the SDR is "on" frequency and that you're not seeing frequent reports of "Errors" or "CRC's" in the DSDPlus Event Wndow/Logs.
Next expermint with -u<num> Unvoiced speech quality (1-64) [-u3] settings in your batch file that runs dsdplus.exe. I am gettng very acceptable IMBE audio with a setting of -u12 while using an Airspy Mini with DSDPlus Fastlane.
Bill