The Mano Ultra mkII is essentially a Raspberry Pi (3B) with some kind of hat and a linear power supply in one package. The i2s transmitter module is from Audio-GD (I bought one a few years ago and still have it in my gadget drawer). From the looks of the hat that feeds the i2s module, it looks like it may be a custom job from Audio-GD as well, but I don’t know for sure - the layout, components, etc. SEEM to be his ‘style.’
I am currently running JRiver on my Pi4B using IanCanada’s modules to sling i2s, and it works/sounds great. After another poster asked, I decided to do a free trial for Qobuz to see what it is capable of as far as internet sources, and using BubbleUpnp, or MConnect, it streams fine.
Both apps can see my local library (in the Pi), my library in my Synology, and connect to Qobuz. Both apps see JRiver AND the Bridge II as separate renderers to send to.
The only glitch I initially came across was if I streamed from Qobuz to the Pi, to output i2s to the DS, on 24/192 (only) it would drop the first fraction of a section because of hardware startup. JRiver has a variable setting, “play silence at startup for hardware synchronization” for instances where DACS, receivers, etc., has a slight delay in activating output (it does not affect continuous tracks). After setting it for 1 second (the lowest setting possible), no more drops.
My post about it is here: