Just a quick explanation on what DigiOne really is 
Master codec . (basically it means that RPI is not using its jittery clocks…the WM8805 (dirty side) has a clock (on clean side separated by a galvanic digital isolator) and RPI only sends the DATA to it on each clock (bclk/lrclk)
Once data is received the WM8805 makes the spidif stream . (still dirty side)
Spidif stream passes the isolator barrier (picking up jitter but removing any HF noise)
Now on the clean side… you have the clocks and 2 set of flip flops(pay attention to fact there are 2 sets). Since the spidif stream is made using the same clocks…there are no buffer over/under runs (one time domain)
On first flipflops…we realign the data on clean MCLK …therefore the MCLK jitter = spidif jitter (+ extremely low extra jitter from flip flop in the 0.0xps) = 0.4ps
On second FF…we take care of a phenomenon called metastability https://en.wikipedia.org/wiki/Metastability_in_electronics (no one is doing that)
So you see…what DigiOne really is…is a master codec with digital/electrical/ground isolation from RPI AND wm8805 and a reclocker (with metastability taken into account)
Simple.