when you are using the RasPi and outputting through USB to the 818, you have the option to use the DoP protocol, which is DSD over PCM. after the data is in the 818, it gets converted to PCM and then sent to DSP speakers.

If you trust that the 818 has sufficient hardware horsepower to do a good job, or fear there is some audio advantage to doing it this way as opposed to using the built in ID41 and having Roon convert the DSD into PCM before sending to the ID41.

Primary: 818v3+ID41, M6 stereo pair, M SpeakerLink cabling, Sonos+96kHz Cullen, silver DSW
HT: Marantz prepro, 271, DSP3300, 8K SE FL/FR pair, DSP M6x2, DSP320x4 (ceiling), black DSW, 520 RL/RR rear in-walls
Living Room: G65, 640 L/R in-walls, UHD722, MS600
Vac. Home: G61, HD621, 4xDSP3100, DSP3100HC
MDMS:NUC/ROCK+TrueNAS Core 12.0 ZFS file server