At the risk of replying to a long-solved issue (I'm going through this entire thread to catch up), here are my 2 cents anyway, hoping my response can still help others. The CH Precision C1's streaming module works with UPnP/DLNA or Roon RAAT. While the Roon functionality should work with the Extreme, it won't yield the very best sound from it. This is no fault of the C1's streaming module (it's actually great) but because the Extreme's USB output section is so very well-implemented. In addition, the Extreme is found by many to sound better when using the Taiko-specific TAS software than when using Roon. The C1 does also allow AES/EBU and S/PDIF connections but as I understand it, the cards that are available for this are not up to the Taiko USB card's standard. Lastly, the C1 also has a proprietary implementation of I2S using a non-standard connector but I doubt that this input could interface with anything except CH components.
AFAIK all our CH customers have moved to using USB.