So this house I bought had a ridiculous whole-home audio system wired thusly:
RCA -> whole home device -> Cat 5e-> wall mounted device in every room that connected cat5e and speaker wires for in ceiling speakers
I have cut all that out and used the existing cat5e wires to run ethernet to every room in the house. However I have not used the speakers for anything.
I am looking for an in-wall device that can connect to and amp the speaker wire, then wifi or ethernet into the network (or at worst bluetooth) and has microphone input for HA assistant.