Any ideas how to broadcast TV audio to the LAN using RPi?

I would like to have the audio from my TV broadcasted to the LAN as an internet radio stream.
That way I could pick it up as an internet radio station in Roon.
Can this be done using an RPi and an USB/HAT audio card?

My current solution is TV audio going to the SPDIF of a Sonos Connect, and a Sonos Play 1 playing the line-in audio from the Sonos Connect.

But I want to replace the Sonos Play 1 by speakers connected to a Roon endpoint.

Most programs that do this introduce significant latency. Delays of several seconds is not uncommon. If you need sync with the display you’re out of luck.
I am sure it is possible though. In the Pro (studio, live) world latency is enemy number one. Whether there is hardware/software for RPi in the Pro sphere is a different question.
Roon is working on an ‘input module’ where audio from ‘something’ can be input to Roon and distributed normally from there. My understanding is that this is low priority.
There is a thread here on the subject:

I’m currently routing TV audio to a Sonos Connect via SPDIF in the living room and playing in the open kitchen with a Sonos Play 1. It seems in sync. Using this only to watch the news while finishing kooking dinner. Would prefer replacing the Sonos Connect by a RPI though.

So let us hope the ‘input device’ in Roon gets a bump up the feature list. The new RAAT (TCP) and Bridge may make this even easier. And Danny Dulai specifically mentions RPi and Cubox.