Do I still need a DDC in between?

This is my current rig:

Wiim Ultra (DH Labs Mirage / Cardas Clear USB, 0.5m) → Gustard U18 (DH Labs HDMI 2.1, 0.5m) → Harmony μDAC (Mogami quad XLR) → Parasound A23 (Belden 5T00UP) → Wharfedale Linton

The sound is very good to my ears—excellent tonality, detail, and especially soundstage, with impressive height and depth. However, I’m considering trying the Volumio Rivo Plus released recently, which offers an I²S-over-HDMI connection.

My question is: would I still need the DDC (i.e., Gustard U18) in between, or would a direct I²S connection from the Rivo+ to the Harmony μDAC deliver comparable or even better sound quality? Have you had any direct or similar experience with this kind of setup? Any advice would be appreciated.