For PCM files Minimum Phase filter 0 is usually best, but some users also like MP filter 2. For DSD files it's a bit more complicated. DSD filter 0 is actually unfiltered, so ultrasonic noise from the DSD process is passed through unattenuated. DSD filters 1 and 2 provide different levels of noise filtering, so you really should try each in your system to determine the preferred setting. Enjoy your new M1 DAC!