I am using HDMIpiMkII (RaspberryPi5 GentooPlayer) and Musician Draco with i2s transmission. I have used Topping and RME products in the $200 to $1,000 range, but the sound quality is completely different from those. It is very smooth and has high resolution, and I want to listen to it forever. It took a little effort to get the sound to come out, so I will summarize the settings.
(1) HDMIpiMkII: Jumper Switch S1 settings
DIP1: ON DIP2: ON DIP3: ON DIP4: OFF (master clock is not output)
The initial state is all OFF, and i2s signals are not output from the HDMI terminal, so you must set it.
(2) Musician Draco: Set i2s mode to Mode5
The lamps [1X] and [4X] at the bottom right of the front panel should be lit. The mode setting method is described in the user's manual (i2s PIN configuration of DRACO).
(3) Connecting HDMIpiMkII to Musician Draco
I use ECDH-HD14SS03BK (made by ELECOM).