It sounds like what you want to do is covered in this thread:
That is, you want to use your Nucleus as both Core and Endpoint. The Peachtree Nova (an integrated amp with embedded DAC) is not a Roon-ready device. It will not be the endpoint, the Nucleus will be (unless you attach a Roon-ready, networked streaming device to the Nova via USB/coax/RCA/Toslink).