Preciso can be connected to Rivo+ via USB or via I2S over HDMI. Both connections support up to PCM 768 kHz/32-bit and DSD512.
Connect the USB output of Rivo+ to the USB input of Preciso.
Power on Preciso first, then Rivo+.
Select the USB input on Preciso with the left knob.
In Volumio go to Settings → Playback Options → Output Device and select Preciso, then save.
Connect the I2S (HDMI) output of Rivo+ to the I2S input of Preciso with a standard HDMI cable, as short as possible.
Power on Preciso first, then Rivo+.
Select the I2S input on Preciso with the left knob.
In Volumio go to Settings → Playback Options → Output Device and select S/PDIF + AES/EBU + I2S, then save.